@article{ author = {Barakati1, S.I. and Daneshjoo, F.}, title = {Seismic Demand and Capacity of Steel Moment Resisting Frames Under Near-Fault Earthquakes Using Incremental Dynamic Analysis}, abstract ={In seismic performance based design procedures, nonlinear static pushover analysis (SPO) and incremental dynamic analysis (IDA) are usually used for determining seismic demand and capacity of moment resisting frames (SMR). The results of these methods are often presented using curves of intensity measures (IM) Vs damage indexes (DI). For far field earthquakes, different intensity measures, such as acceleration spectral intensity of the first mode of vibration with 5% damping i.e. Sa (T1, %5) factor are used. But for near field earthquakes, it is necessary to consider other suitable IM's. In this article, the difference between IDA and SPO curves for near field earthquakes compared to that for far field earthquakes are shown for three SMR frames which are designed according to Iranian code of practice using 15 pairs of near and far field earthquakes. Then some other intensity measure factors which may be suitable for near and far field earthquakes, are considered. These IM's are compared with the use of standard definitions of "efficiency" and "sufficiency". It is concluded that intensity measure IM1I&2E which considers second mode effects and nonlinear behavior, is much more efficient and better sufficient than more often used Sa(T1, %5) factor.}, Keywords = {Near and far field earthquakes,Intensity measures,Nonlinear static pushover analysis,Incremental dynamic analysis}, volume = {14}, Number = {1}, pages = {1-14}, publisher = {Tarbiat Modares University}, title_fa = {تقاضا و ظرفیت لرزه ای قاب های خمشی فولادی تحت تأثیر زلزله نزدیک گسل با استفاده از تحلیل فزاینده دینامیکی}, abstract_fa ={در طراحی بر اساس عملکرد از تحلیل استاتیکی غیرخطی بار افزون و تحلیل دینامیکی فزاینده برای تعیین تقاضا و ظرفیت لرز های قاب های خمشی فولادی استفاده م یشود . هر کدام از این رو شهای تحلیل حداقل با دو کمیت : الف ) شاخص برای زلزل ههای دور از گسل، استفاده از شاخ صهای شدتی مانند     IDA شدت و ب) شاخص خسارت مشخص می شوند. در روش شتاب طیفی اولین مود ارتعاش قاب با میرایی پنج درصد توصیه شده است ولی برای زلزل ههای نزدیک گسل در کنار این شاخص   ضروریست شاخ صهای شدت مناسب دیگری نیز در نظر گرفته شود     . در این مقاله با استفاده از سه قاب خمشی ویژه فولادی که بر برای سازه ای مفروض در یک     IDA و SPO اساس آیین نامه های ایران طراحی شد هاند، نشان داده شده است که چنانچه منحن یهای دستگاه مختصات رسم شوند تفاوت هایی بین حالت استفاده از رکور دهای دور از گسل و نزدیک گسل وجود دارد     . همچنین در این مقاله با در نظر گرفتن چند شاخص شدت دیگر که در ارزیابی عملکرد ساز ههای واقع در نزدیکی گسل و یا دور از گسل کاربرد   دارند، به مقایسه بین این شاخ صها، با استفاده از تعاریف معیارهای     "کارایی" و "کفایت" پرداخته شده است. در پایان مشاهده شده که مشارکت مد دوم و همچنین اثرات غیر ارتجاعی را در     IM1I&2E شاخص شدت ،Sa(T1,% که در مقایسه با شاخص شدت مرسوم ( 5   نظر می گیرد، بسیار کاراتر و با کفایت تر است}, keywords_fa = {واژگان کلیدی: رکورد های نزدیک گسل,رکورد های دور از گسل,تحلیل دینامیکی فزاینده,تحلیل استاتیکی بار افزون,شاخص شدت}, url = {http://mcej.modares.ac.ir/article-16-3944-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-3944-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Dahrazma, B. and Mousavi, S.M.}, title = {Investigation on the Quality of Groundwater Resources of South of Birjand Plain Using Mass Balance Techniques}, abstract ={Groundwater is of important drinking water resources. The quality of those water resources which are not affected by human activities, is characterized by local geological conditions. The present research was conducted in order to investigate the quality of water resources located in the south of Birjand plain, South Khorasan Province, using mass balance techniques. This research dealt with the quality assessment and the distribution pattern of physico-chemical parameters (anions and cations, pH, EC, TSS, TDS, and TH) in the groundwater resources in the region resulting in indentifying the contamination resources. Also, the origins of anions and cations in the groundwater resources as well as their connection with the geological characteristics of the region were evaluated by employing the mass balance techniques. The water sampling was performed systematically based on the distribution wells over the plain, with regard to the distances, and perpendicular to the topographical lines from the heights toward the lower plains down to the main river, 3 kilometers apart across the plain. In average, one third of whole wells in the study area were selected for sampling. The samples were taken during the end of dry season (October 2010) from 27 wells, 2 Qanats, and 1 spring. The cations (Na +, Ca+2, Mg+2, and K+), anions (HCO- 3 , SO 4 2-     , CO 3 2-     , and Cl-), TSS, TDS, pH, and the total hardness of the water samples were measured in the Water, Soil, and Plant   Laboratory, Kavosh Ab Shargh Khorasan Jonobi Engineering Services Co.   To assess the quality of the water resources in the region, in this research the physicchemical   properties of water samples were compared with ISIRI 1053 to identify the contaminated wells. The hardness of the samples was measured and the water resources types were identified using Piper Diagram. Also, through calculating the correlation factors and mass balance, hydrogeochemistry of water resources and probable origin of cations and anions were assessed. The results showed that 50%, 30%, and 10% of the groundwater resources are contaminated with magnesium, sodium, and chloride respectively. The petrological studies verified the presence of ophiolite sequence. A set of ultramafic rocks and basic magma (spilites) with wide developments in southern heights of Birjand plain which had the most effects on the water quality of the region. The water resources contaminations in the region may be due to the presence of listonites from the alteration of ultramafic rocks existed in highlands, upstream of the groundwater resources. 96% of groundwater resources are classified as very hard water. The types of groundwater vary from carbonated calcic in highlands to chloride sodic in downstream and east of the region due to high solubility of Na + and Cl- existing in the soil. %36.6 of water resources were chloric-sodic and the rest were classified as chloric-magnesic, bicarbonatesodic, and bicarbonate-magnesic. The correlation analysis of the parameters indicated that sodium has a very high correlation with chloride, potassium, and sulfate. The positive correlation of Mg 2+ with Ca2+ (+0.614) is an indication of the same origin for both ions. Also, EC with TH (+0.710) and Ca 2+ (+0.710) and TH with TSS (+0.641) show positive correlation. In general, these positive correlations indicate the common geogenic origin of cations and anions in water resources of the region. WATEVAL software was employed for calculating the mass balance using the concentration of anions and cations to find the effective parameters and origin of ions in the water resources. These calculations verify and emphasize on the influence of geological conditions of the region on hydrogeochemical properties of water resources of the plain. Mass balance analysis denotes that the origin of sodium and potassium could be the ion exchange process originated from weathering of mafic rocks (spilites) while the calcium may be released due to weathering of plagioclases of sub-volcanic mass, ferromagnesian minerals, carbonated listonite, and dissolution of limestone in the region.  }, Keywords = {groundwater quality,Contamination,mass balance,south of Birjand plain}, volume = {14}, Number = {1}, pages = {15-28}, publisher = {Tarbiat Modares University}, title_fa = {بررسی کیفیت منابع آب زیرزمینی جنوب دشت بیرجند با استفاده از تکنیک تعادل جرمی}, abstract_fa ={محدوده مطالعه شده، جنوب دشت بیرجند واقع در استان خراسان جنوبی است . در این پژوهش به ارزیابی کیفیت و در منابع آب زیرزمینی منطقه     (TH ،TDS ،TSS ،EC ،pH ، چگونگی پراکنش مقادیر پارامترهای فیزیکوشیمیایی ( آنیون ها و کاتیونها پرداخته شده و منابع آلوده کننده مشخص شده است     . همچنین در پژوهش حاضر منشأ آنیو نها و کاتیون های موجود در منابع آب زیرزمینی و ارتباط آنها با شرایط زمین شناسی منطقه با استفاده از محاسبه تعادل جرمی ارزیابی شده است     . برای نیل به این هدف، ازمیان     100 چاه بهر هبرداری در منطقه، از 30 منبع آب زیرزمینی نمونهبرداری انجام و آنالیز شده است. نتایج نشان می دهند که به   30 % و 10 % منابع آب زیرزمینی مطالعه شده به منیزیم، سدیم و کلر آلوده است. آلودگی منابع آب م ی تواند حاصل ،% ترتیب 50   حضور لیستونیت های حاصل از دگرسانی سن گهای اولترامافیک موجود در ارتفاعات بالادست منابع آبی باشد . 96 % منابع آبی در محدوده آ بهای بسیار سخت قرار میگیرند     . تیپ منابع آب در ارتفاعات بیشتر کربناته کلسیک و به سمت پایین و شرق منطقه به بیشتر کلروره سدیک است     . محاسبه همبستگی پارامترها معلوم می کند که سدیم با ک لر، پتاسیم و Cl- و Na+ دلیل حلالیت بالای سولفات همبستگی بالایی را نشان میدهد     . با استفاده از محاسبه تعادل جرمی میتوان منشأ سدیم و پتاسیم موجود در منابع آبی را فرایند تبادل یونی با منشأ هوازدگی سنگهای مافیک     (اسپیلیتها)، و منشأ کلسیم را هوازدگی پلاژیوکلازهای توده های ساب -   ولکانیکی، کانی های فرومنیزین و لیستونی تهای کربناته و انحلال سنگ آهکهای منطقه در نظر گرفت   .  }, keywords_fa = {کیفیت آب زیرزمینی,آلودگی,تعادل جرمی,جنوب دشت بیرجند}, url = {http://mcej.modares.ac.ir/article-16-8549-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-8549-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Shafieefar, M. and Adjami, M. and SalehiNeyshabouri, S.A.A.}, title = {An investigation on Effects of Bed Permeability on Characteristics of Turbulent Flow in Various Porosities}, abstract ={Abstract: The two main characteristics of a porous bed are the bed material diameter – representing its coarseness - and the porosity which represents its permeability. In this paper the effect of bed permeability on the average structure of flow turbulence is investigated. Flow is modeled using an innovativecontinuum approach based on Volume Averaged Navier-Stokes Equations in several different channel bed porosities. Results of four different simulations with various porosities are presented. Bed permeability can be represented by the permeability Reynolds number, Rek, which is the ratio of effective diameter of porosity and the length scale of eddies near the bed. The Reynolds permeability number (Rek) is the best expression for the bed permeability quantity. In small Rekthe bed acts as a solid/rigid boundary and in large Rek, the bed will behave as a high permeable boundary with negligible viscosity effects. Under these conditions, the turbulence eddies along the flow are rarely observable. The reasons can be due to: 1) the mechanism of free turbulence transfer through permeable layer and/or 2) a considerable decrease in the average shear stress due to no wall-blocking and low-viscosity effects. The dominant characteristic of turbulence near a high permeable bed is relatively large eddy structures, probably originating from so-called Kelvin-Helmholtz instabilities. Suchflow pattern with large vortexes leads to high momentum exchange between the free channel flow and the two-phase flow in porous media below permeable bed. This process also increases the friction between flow and the substrate and therefore will result in moving the Logarithmic-low region slightly downward. In addition, it is observed that the log-low cur near a high permeable bed is 4% steeper than in solid and rough bed.}, Keywords = {Continuum approach,Permeable bed,Porosity,Average flow,Navier-Stokes equations,turbulence flow}, volume = {14}, Number = {1}, pages = {29-48}, publisher = {Tarbiat Modares University}, title_fa = {بررسی تأثیر نفوذپذیری بستر کانال مسطح بر ویژگ یها و ساختار متوسط جریان آشفته در تخلخل های گوناگون}, abstract_fa ={چکیده - بستر نفوذپذیر با دو ویژگی اصلی آن، قطر متوسط (نماینده ی درشتی ذرات) و تخلخل (نماینده ی درصد نفوذپذیری )، بیان می شود . در مقاله حاضر تأثیر نفوذپذیری بستر بر ساختار متوسط آشفتگی جریان بررسی شده است . جریان، روی یک بستر نفوذپذیر به روش پیوستار با بهر هگیری از معادلات متوسط گیری شده حجمی ناویر استوکس مد ل سازی شده و نتایج چها ر   شبیه سازی با تخلخل های گوناگون ارائه شده است     . نفوذپذیری بستر را می توان به وسیله ی عدد رینولدز نفوذپذیری ( نسبت قطر مؤثر های کوچک، بستر به صورت مرز صلب رفتار     Rek توصیف کرد. در (Rek ، حفر ه ها به مقیاس طولی گرداب ههای آشفتگی مجاور بستر های بزرگ، مرز میدان مانند بستری با نفوذپذیری زیاد     (با اثرات لزجت قابل اغماض) رفتار خواهد کرد . در Rek کرده و به عکس در این شرایط، گرداب ههای آشفتگی نزدیک بستر در امتداد جریان به ندرت قابل تشخیص خواهند بود     . می توان دلیل این امر را 1) انتقال آزاد آشفتگی در مرز نفوذپذیر و     /یا 2) کاهش تنش برشی متوسط به واسطه عدم وقوع پدیده ی انسداد بستر و تأثیر ناچیز لزجت ناشی از حضور بستر دانست     . مشخصه غالب آشفتگی در مجاور بستر با نفوذپذیری زیاد، ساختارهای گردابه ای نسبتا بزرگی هستند که احتمالا نشات گرفته از پدید هی ناپایداری کلوین     -هلمهولتز جریان هستند. همین ساختارها عامل تبادل مومنتوم بین جریان عمو می کانال و جریان دوفازی داخل بستر نفوذپذیر است     . این فرایند سبب افزایش اصطکاک بستر شده و در نتیجه محدوده برازش ناحیه   1 برابر / لگاریتمی کمی به سمت پایین منتقل م یشود. فزون بر این مشاهده گردیده که شیب منحنی قانون لگاریتمی در حدود 04   شیب معمول آن در جریان های آشفته مجاور بستر های صاف و زبر است   .  }, keywords_fa = {رویکرد پیوستار,بستر نفوذپذیر,جریان متوسط,معادلات ناویر-استوکس,جریان آشفته}, url = {http://mcej.modares.ac.ir/article-16-1304-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1304-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Gholhaki, M. and Gerami, M. and .Mahdipour, A}, title = {Story Shear and Story Drift Determination of Thin Steel Plate Shear Walls with Hinge Beam to Column Connections under Far and Near Fault Earthquakes}, abstract ={Abstract: Regard to investigations that are done about destructive earthquakes contemporarily and by contemplating on effects of different earthquakes on various types of structural systems and by recording acceleration of ground motions , researchers detected different effects of destruction in range about 15 to 60 kilometers far from epicenter of earthquake that is nominated as near fault earthquakes. the subsequences of researches which have been done in this field shows that mapping near to the fault have less effective time than mapping which are far from the fault and have one or more special pulse with a large domain and with medium to large frequency which causes to increase the domain of response spectrum in the zone of large period. and applying huge energy in short time and Sudden intense pulse in the beginning of near fault timehistories causes increasing the demand of rotational ductility in some stories and joints. In this article Regard to reliability of steel plate shear walls in recent four decades and also the fact that these structural systems have appropriate ductility to control displacements, height energy dissipation and ductile failure mechanism, the dynamic behavior of these systems is investigated .Four finite element models of 3,7,15 and 25 story buildings that used steel thin plate shear wall with hinge beam to column connections as resistant systems has created and analyzed through nonlinear dynamic analysis in ABAQUS finite element software and then response of structures such as story shear and drift angles of stories were detected. Results postulate the effects of shear distribution in near fault and regard to these purposes it seems that this fact is caused of effects of higher modes in far fault earthquakes. This situation cause of the fact that the frequency containers of near fault earthquakes are higher in range of height periods .besides Response of structures such as damage index and base shear, show that in tall steel plate shear walls (T>0.7s) effect of near fault movements on response parameters are more than those in the far fault zone. It also can be seen that base shear of the structures in far fault earthquakes fluctuates in more extended range compared to which happens in near fault structures and in near fault earthquakes base shear of most time histories don’t have much differences but in far fault earthquakes differences are relatively much. By increasing the height of SPSW’s differences between displacements in near fault and far fault earthquakes ascends. Maximum of differences between near fault and far fault responses appear in boundary of 40% to 60% of height of walls. Eventually can be said that not only higher PGA of most near fault earthquakes is a distinctive attribute in accordance with far fault earthquakes, but also higher frequency container in long period range would be devastating, regardless to higher PGA of these earthquakes.}, Keywords = {Thin Steel Plate Shear Wall,Hinge connection,Near Fault Earthquake,Nonlinear Dynamic Analysis}, volume = {14}, Number = {1}, pages = {49-62}, publisher = {Tarbiat Modares University}, title_fa = {بررسی برش و نسبت جابه جایی دیوارهای برشی فولادی با ورق نازک دارای اتصال مفصلی تحت نگاشت های دور و نزدیک گسل}, abstract_fa ={چکیده - در سال های اخیر با مطالعه انجام گرفته روی زلزل ههای مخرب و زمین لرزه های متفاوت روی سیست م های سازه ای مختلف و ثبت نگاشت شتاب زلزل ههای به وقوع پیوسته، تفاوت آثار خراب یهای ایجاد شده در محدوده 15 تا 60 کیلومتری مرکز وقوع زمین لرز هها     (که حوزه نزدیک گسل نامیده می شود) نسبت به خرابی های پیدا شده در خارج از این حوزه مشخص شده است .   با توجه به سختی مناسب سیستم دیوار برشی فولادی برای کنترل تغییر شکل سازه و مکانیزم شکست شکل پذیر و اتلاف انرژی بالا، در این مقاله به بررسی رفتار دینامیکی دیوار برشی فولادی دارای اتصال تیر به ستون مفصلی تحت زلزله های نزدیک و دور از گسل پرداخته شده است   . 15     و 25 طبقه دیوار برشی فولادی به وسیله تحلیل دینامیکی غیرخطی تحت چهار جفت ،7 ، چهار مدل اجزاء محدود 3   تحلیل شد . پاسخ سازه ها شامل برش و زاویه دریفت طبقات نشان ABAQUS نگاشت دور و نزدیک گسل در نرم افزار اجزاء محدود دهنده آثار بیشتر توزیع برش در حوزه دور از گسل بوده که این موضوع به دلیل آثار بیشتر مودهای بالاتر در حوزه دور از گسل     0 ثانیه) اثر حرکات نزدیک گسل بر پارامترهای پاسخ / نسبت به حوزه نزدیک گسل است. در قا بهای بلن دمرتبه (بیش از پریود 7   سازه بیشتر از حرکات حوزه دور از گسل بوده که این مسأله به دلیل بیشتر بودن محتوای فرکانسی نگاشت های دور از گسل در محدوده پریود کوتاه و محتوای فرکانسی بیشتر حوزه نزدیک گسل در محدوده پریود بلند است   .  }, keywords_fa = {دیوار برشی فولادی با ورق نازک,اتصال مفصلی,تحلیل دینامیکی غیرخطی,حوزه نزدیک گسل}, url = {http://mcej.modares.ac.ir/article-16-1595-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1595-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Gholipour1, Y. and Shahbazi, M.M.}, title = {Decreasing computational effort in structural optimization using a multifidelity metamodel}, abstract ={Abstract: High fidelity models are becoming increasingly common in engineering optimization. The computation burden is often caused by expensive analysis and simulation processes in order to reach a comparable level of accuracy as physical testing data. The metamodels are initially developed as surrogates of the expensive simulation process in order to improve the overall computation efficiency. This work presents a new multilevel optimization approach for multidisciplinary structural design optimization based on multi fidelity modeling to decrease computational effort. Such method is a composition of a statistical estimating method and a metaheuristic algorithm. A low fidelity analysis response determines if the high fidelity analysis should be done or not. As a result, most of unnecessary high fidelity calculation will be omitted. The empirical results show the new algorithm causes a significant decrease in computational load as well as increase in convergence rate. Keywords: Multi level optimization; Metamodeling; Harmony search algorithm; Inverse distance weighting model.}, Keywords = {Multi level optimization,Metamodeling,harmony search algorithm,Inverse}, volume = {14}, Number = {1}, pages = {63-72}, publisher = {Tarbiat Modares University}, title_fa = {کاهش محاسبات بهینه سازی خرپا با استفاده از یک الگوریتم فرامدل ترکیبی}, abstract_fa ={امروزه، مدل های دقیق رایانه ای کاربرد وسیعی در بهین هسازی مهندسی پیدا کرده اند . ارزیابی و محاسبه اکثر این مدل ها، نیازمند صرف زمان و هزینه زیادی است     . در این مقاله یک روش جدید فرامد لسازی ترکیبی به منظور کاهش بار محاسباتی برای رسیدن به جواب بهینه در مسائل مدل سازی ارائه شده، این الگوریتم در ابتدا تعدادی نقاط نمونه ایجاد کرده، مقادیر پاسخ آنها را با   استفاده از محاسبات دقیق به دست آورده و سپس مقدار پاسخ تقریبی نقاط جدید را به دست می آورد     . در صورتی که پاسخ تقریبی به دست آمده در راستای همگرایی الگوریتم باشد، دست به محاسبه پاسخ دقیق آن خواهد زد     . برای ارزیابی تأثیر این الگوریتم بر کاهش بار محاسباتی، چند مثال عددی استاندارد ارائه و نتایج آن با چند الگوریتم متداول بهین ه سازی همچون الگوریتم ژنتیک و   کولونی مورچه ها مقایسه شده است     . مقایسه نتایج نشان می دهد که این الگوریتم تأثیر زیادی بر کاهش بار محاسباتی و افزایش سرعت همگرایی دارد       .  }, keywords_fa = {بهینه سازی سازه,فرامدل سازی,الگوریتم جستجوی هارمونی,روش توزین عکس فاصله}, url = {http://mcej.modares.ac.ir/article-16-9362-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9362-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {.KaramiMohammadi, R and Sharghi, A.H.}, title = {Seismic design of SMRF structures using different load patterns and their comparison with the optimum design}, abstract ={Currently, seismic design provisions of most building codes are based on strength or force (base shear) considerations. These building codes are generally regarding the seismic effects as equivalent static forces with a height wise distribution which is consistent with the first vibration mode shape. However, the design basis is being shifted from strength to deformation in modern performance-based design codes. This paper presents a practical method for optimization of steel moment resisting frames (SMRF), based on the concept of uniform deformation theory. This theory is based on this concept that the structural weight of a lateral load resisting system with uniformly distributed ductility demand-to-capacity ratio (or any other damage index) will be minimal compared to the weight of an ordinary designed system in which deformation is not distributed uniformly and just some of structural elements have reached their ultimate states. The state of uniform deformation can be achieved by gradually shifting inefficient material from strong parts of the structure to the weak areas. In the first part of this paper, the uniform deformation theory is implemented on 3, 5 and 10 story moment resisting frames subjected to 12 earthquake records representing the design spectrum of ASCE/SEI 7-10. This includes design of an initial structure according to conventional elastic design procedures, followed by an iterative assessment process using nonlinear dynamic analyses till the state of uniform deformation is achieved. Results show that the application of uniform deformation theory leads to a structure with a rather uniform inter-story drift distribution. Subsequently, the optimum strength-distribution patterns corresponding to these excitations are determined, and compared to four other loading patterns. Since the optimized frames have uniform distribution of deformation, they undergo less damage in comparison with code-based designed structures. Also, as the shear strength of each story is in proportion to the weight of that story, the optimized structures have minimum structural weight. For further investigation, the 10 story SMRF is redesigned using four existing load patterns and subjected to 12 earthquake excitations. Then a comparison is made between maximum beam rotations of each model and those belonging to the optimized one which revealed that the optimized SMRF behaves generally better than those designed by other loading patterns. Also, it is found that for none of the conventionally designed SMRFs, beam rotation demand is distributed uniformly. In other words, for all of the considered load patterns the maximum rotation of the beams in some stories exceeds the rotation associated with the performance level. Finally, assuming that the probability distribution of maximum rotations under different excitations follows a lognormal distribution, the probability of exceeding the allowable rotation associated with the LS performance level is calculated for different load patterns and compared to each other. Based on this comparison, the efficiency of each loading pattern is evaluated and the best one is determined. Application of optimization method presented in this paper avoids the concentration of deformation and damage in just one story and makes each story deformation and damage uniform over the height of the structure.}, Keywords = {performance-based design,Structural optimization,Uniform Deformation Theory,Seismic Loading Pattern,nonlinear dynamic analysis}, volume = {14}, Number = {1}, pages = {73-84}, publisher = {Tarbiat Modares University}, title_fa = {طراحی لرزه ای قاب های خمشی بر اساس الگوهای بار جانبی گوناگون و مقایسه آن ها با طرح بهینه}, abstract_fa ={- مبنای طراحی سازه هایی که بر اساس آیین نامه های لرزه ای طراحی می شوند، مقاومت یا نیرو (برش پایه) است . با این حال در سال های اخیر، اساس آیین نامه های مبتنی بر طراحی عملکردی، از طراحی بر اساس نیرو به طراحی بر اساس جابه جایی تغییر کرده است . در این مقاله چگونگی بهین هسازی قاب های خمشی فولادی با استفاده از تئوری تغییر شکل های یکنواخت توضیح داده شده و در ادامه از این روش برای بررسی کارایی الگوهای بارگذاری مختلف استفاده شده است       . 5     و 10 طبقه با طراحی لرزهای بر اساس تئوری تغییر شکل یکنواخت، تحت 12 ، در بخش نخست مقاله، قابهای خمشی 3   است، بهین هسازی شده ؛ با پخش یکنواخت خرابی در این ASCE/SEI 7- رکورد زلزله مختلف که طیف آن ها سازگار با طیف آیین نامه 10   سازه ها، میزان خرابی و وزن قابهای طراحی شده، کمینه شده است . سپس با آنالیز دینامیکی تاریخچه زمانی غیرخطی روی قابهای و سه روش که پژوهشگران دیگری     ASCE/SEI 7- بهینه و مقایسه پاسخ آنها با پاسخ سازههای طراحی شده بر اساس آییننامه 10   پیشنهاد کردند، اثر بهین هسازی در کاهش خرابی قابها نشان داده شده است . همچنین میزان کارایی روشهای مختلف طراحی نسبت به طرح بهینه بررسی شده و با تحلیل احتمالاتی پاسخها، اثر استفاده از روشهای طراحی نام برده ارزیابی شده است       .  }, keywords_fa = {الگوهای بارگذاری,طراحی بر اساس عملکرد,بهین هسازی,تئوری تغییر شک لهای یکنواخت,پخش برش}, url = {http://mcej.modares.ac.ir/article-16-1981-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1981-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Golshani, A. and Nemati, R.}, title = {Numerical model of cone penetration determinate difference in cohesive soil:}, abstract ={The cone-penetration test (CPT) is a well-established in situ test in geotechnical engineering for soil classification and estimation of soil properties. In a CPT, a cone shaped penetrometer is pushed into the ground at a constant rate. The resistance on the cone tip is measured and is then related to soil classification and soil properties. In this research, the finite difference analysis of large deformations for the cone penetration testing (CPT) in the cohesive soil have been conducted using FLAC 2D Software. In this modeling, interface elements between penetrometer and soil are considered and it is assumed that the penetrometer materials show rigid behavior in reaction to the soil materials. FLAC provides interfaces that are characterized by Coulomb sliding and/or tensile separation. Interfaces have the properties of friction, cohesion, dilation, normal and shear stiffness, and tensile strength there is an in-situ state of stress in the ground, before any excavation or construction is started. In FLAC 2D, an attempt is made to reproduce this in-situ state by setting initial conditions. Ideally, information about the initial state comes from field measurements. Boundary conditions are modeled as axesymmetry. Horizontal and vertical direction at the bottom boundary and horizontal direction at the vertical boundary of soil model are fixed. Soil behavior follows full elastic–plastic model and Mohr-Coulomb failure criterion. Numerical model is analyzed to achieve mesh convergency at the various grids. The values of cone and frictional resistance have been obtained through software calculations and then compared with the results obtained from cone penetration test at the aluminum melt factory in Lamard, Fars Province. Stress and displacement contours are related for evaluation of the penetration process. Steady state is considered to achieve steady stress range in which the hole diameter is equal with the CPT hole. The numerical modeling results of CPT test by FLAC 2D software shows good agreement with the field tests results. Furthermore, the results have been discussed by using Robertson Chart 1986 and Eslami- Felonious Chart 1997. Charts almost show same profile with the field test results at the aluminum melt factory site.}, Keywords = {finite difference analysis,Cone penetration,Cone resistance,Interface element,Mesh Convergency}, volume = {14}, Number = {1}, pages = {85-98}, publisher = {Tarbiat Modares University}, title_fa = {مدل سازی عددی تفاضل محدود نفوذ مخروط در خاک چسبنده}, abstract_fa ={در این پژوهش، آنالیز تفاضل محدود تغییر شکل های بزرگ برای آزمایش نفوذ مخروط انجام می شود . در این مدل سازی، المان سطح مشترک بین نفوذسنج و خاک در نظر گرفته شده و مصالح FLAC 2D استفاده از نرم افزار نفوذسنج به گونه ای فرض می شود که در برابر مصالح خاک، رفتاری صلب داشته باشد     .رفتار خاک از مدل الاستیک- پلاستیک کامل و معیار موهر     -کولمب تبعیت می کند. پارامترهای مقاومت نوک و مقاومت اصطکاکی از محاسبات نر مافزار به دست آمده و سپس با نتایج آزمایش صحرایی نفوذسنج مخروطی     (از سایت پروژه کارخانه ذوب آلومینیم در شهر لامرد واقع در استان فارس ) ، مقایسه می شود     . نتایج مدل سازی عددی، تطابق خوبی با نتایج آزمایش صحرایی نشان می دهد. همچنین مش بهینه، حالت نفوذ دائم، ارزیابی نتایج با نمودار رابرتسون     1986 و نمودار اسلامی و فلنیوس ( 1997 ) هم بررسی شد .  }, keywords_fa = {آنالیز تفاضل محدود,نفوذ مخروط,مقاومت نوک,المان سطح مشترک,مش بهینه}, url = {http://mcej.modares.ac.ir/article-16-7134-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7134-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Kaboorani, S. and Shanehsazzadeh, , A.}, title = {Modeling the Saltation and Evaluating the Parameters Affecting the Random Movement of Sediment Particles in Bed Load Transport Under Steady Flow}, abstract ={Study on the physics of sediment particle movement at grain scale is essential for better understanding sediment transport phenomenon and estimating the rate of sediment transport in rivers and marine environment. Sediment particles basically transport in two modes of bed and suspended load. Bed load takes place through sliding, rolling and saltation, from which the latter is dominant. Many parameters influence on saltation phenomenon, which their effects are not fully understood. These influencing parameters make the saltation a stochastic phenomenon. In the present article the influence of the affecting parameters on movement of sediment particles at saltation mode of transport under unidirectional steady flow are investigated. A numerical model is developed to simulate the particle motion in bed load saltation with considering the main contributor forces. Then the influencing parameters that effect on the jump length and average velocity of the particles are studied. Among them are the initial condition, the particle position between other particles and the shape of particles. The influence of the velocity profile on the jump length and average velocity of the particles are also studied. In summary, the change in the initial condition including the initial velocity and angle produces less than 10% variation on the particle jump length and velocity. On the other hand the position of the grain between the other particles is considerably influential with 40% change in the jump length and average velocity. The particle shape is most important parameter in term of the influence on the jump length and average velocity; there is a 50% difference between the jump length of spherical particles and flake-shape particles, for average velocity it is about 10%. The result of the study improves our understanding of particle motion at grain scale and ultimately results in the better estimation of sediment transport rate. }, Keywords = {sediment transport,bed load,steady flow,saltation,Numerical Modeling}, volume = {14}, Number = {1}, pages = {95-104}, publisher = {Tarbiat Modares University}, title_fa = {شبیه‌سازی و بررسی اثر عوامل مؤثر بر حرکت تصادفی ذرات رسوب بار بستر در جریان ماندگار}, abstract_fa ={ بررسی انتقال رسوب در مقیاس حرکت ذرات باعث شناخت بهتر پدیده‌ی انتقال رسوب و تعیین نرخ آن در محیط‌های رودخانه و دریا می‌شود. ذرات رسوب به‌طور معمول به دو صورت بار معلق و بار بستر تحت تأثیر جریان و یا امواج، منتقل می‌شوند. بار بستر به‌صورت‌های لغزش، غلتش و پرش انتقال پیدا می‌کند که در میان آن‌ها پرش غالب است. در فرایند پرش عوامل متعددی تأثیرگذارند، اما به دلیل روشن نبودن کامل این عوامل، پدیده‌ی پرش ذره تاحدی تصادفی درنظرگرفته می‌شود. از جمله‌ی این عوامل می‌توان به اثر شکل ذره، محل قرارگیری آن و آشفتگی جریان اشاره نمود. در این مقاله میزان پرش ذرات و سرعت متوسط آن‌ها و تأثیر عوامل یاد شده بر آن در جریان ماندگار با استفاده از مدل ریاضی بررسی می‌شود. از عواملی که به‌طور ویژه توجه شده، تأثیر شکل ذرات و محل قرارگیری آن بر طول و سرعت پرش ذره است. هم‌چنین یک رابطه‌ی منطقی بین سرعت و زاویه اولیه‌ی پرش و محل قرارگیری آن در بستر برقرار شده است. ازنتایج مطالعات حاضر، در شناخت و تخمین دقیق‌تر رفتار و نرخ رسوب بستر استفاده می‌شود.}, keywords_fa = {پرش,شکل ذره,محل قرارگیری ذره,جریان ماندگار,بار بستر}, url = {http://mcej.modares.ac.ir/article-16-9344-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9344-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Maghrebi, M. and Khanzadi, M. and Habibian, M. and Tadayon, M.}, title = {Study the Influences of Nano-Silica on Electrical Resistivity of Cement Paste}, abstract ={This paper presents the influences of adding nano-silica on electrical resistivity of cement paste, because the electrical resistivity test is one of the non-destructive test in durability issues that can help us to assess the resistance of cement is facing by ion attacks. Furthermore, because the transition area in concrete is one the weak parts of concrete. It is tried to improve the durability properties of transition area that is mainly filled by cement and water. So, this research focuses on assessing the electrical resistivity of cement paste when it is integrated with pozzolan material in nano and micro scale. In to end, the cement paste without any additive is compared with cement paste integrated with nano-silica and micro silica. The amounts of additive materials are limited to 2.5%, 5%, 7.5% and 10% of cement weight. The two types of nano-silica have been used in this research that are liquid suspended nano-silica and solid nano-silica particle. So, the 3 different pozzolan materials were used that include two different nano silica (liquid and solid) and micros silica. Then all the results have been compared with results of ordinary cement paste as reference point. Then the samples were tested at age of 3, 28 and 90 days. The results show that before age of 3 days, adding nano silica or micro silica led to decline the electrical resistivity because the pozzolanic reaction is not started, but at age of 28 days the top achieved electrical resistivity belong to the samples which has nano-silica in its mixture. However, after age of 28 days, just the samples with micro-silica have electrical resistivity growth. The results of the samples that contain the both of nano-silica and micro-silica are between the results of samples that contain micro-silica and the samples which integrated by nano-silica. Keywords:  }, Keywords = {Nano-silica,Electrical Resistivity,Micro-Silica- pozzolan,Cement paste}, volume = {14}, Number = {1}, pages = {99-108}, publisher = {Tarbiat Modares University}, title_fa = {بررسی تأثیر اضافه کردن نانو سیلیس برروی مقاومت ویژه الکتریکی خمیر سیمان}, abstract_fa ={مقاومت ویژه الکتریکی را می توان یک سنجش پتانسیل برای مقاومت و دوام نام برد . غیرمخرب بودن و در عین حال ارزان بودن از مزیت های ویژه این روش به شمار می رود     . در این پژوهش تأثیر نانوسیلیس و میکروسیلیس بر روی مقاومت ویژه الکتریکی خمیر سیمان مورد مطالعه قرار گرفته، برای این منظور نمون ههایی با مقادیر متفاوت از نانوسیلیس و میکروسیلیس ساخته   شده و در سنین     3 و 28 و 90 روزه آزمایش شد. نتایج آزمایش ها نشان می دهد که تا سن 3 روزه، افزایش هر مقدار نانوسیلیس و میکروسیلیس موجب کاهش مقاومت ویژه الکتریکی شده اما در سن     28 روزه بیشترین مقاومت ویژه الکتریکی در نمونه های حاوی نانوسیلیس مشاهده شده است     . اما رشد مقاومت ویژه الکتریکی بعد از این زمان تنها در نمونه های حاوی میکروسیلیس مشاهده شد .   نتایج مربوط به نمونه های حاوی ترکیب هم زمان نانوسیلیس و میکروسیلیس ، در محدوده نتایج بین نتایج حاصل از نمون ه ای حاوی نانوسیلیس و نمونه های حاوی میکروسیلیس است   .   در حالت کلی اضافه کردن نانو و میکروسیلیس به خمیرسیمان باعث افزایش چشمگیر مقاومت الکتریکی در این نمون هها شده، به گونه ای که تنها با اضافه کردن میکروسیلیس به میزان 2.5 درصد وزن سیمان، مقاومت الکتریکی در سن 90 روز رشدی 20   درصدی داشته و در نمون های که به آن 10 درصد وزن سیمان، نانو سیلیس اضافه شده است در سن 90 روزه شاهد افزایش بیش از   50 درصدی مقاومت الکتریکی بوده ایم .  }, keywords_fa = {نانوسیلیس,مقاومت ویژه الکتریکی,میکروسیلیس,پوزولان,ملات سیمان}, url = {http://mcej.modares.ac.ir/article-16-7259-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7259-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Mamdoohi, A.R and MohammadiHazaveh, A. and FallahZavareh, M.}, title = {Aberrant Driving Behavior of Iranian Drivers: An Internet-Based Survey}, abstract ={Road crashes cause more than 20 thousand fatalities each year in Iran. Human factors consisting of driving styles and skills have been recognized as important contribiuting factors in most traffic crashes. Focous on driving behavior has been the subject of many researches. Driver Behavior Questionnaire (DBQ) in this regard is a relatively new, important and widely used instrument, devised to identify the components of the structure of aberrant driving behaviors. Surveys based on DBQ, urges respondents to self-report the frequency of aberrant driving behaviors during a specific period of time. Investigation of driving styles is estimated to be the subject of more than 170 researches since DBQ was first by Reason et al in the 90’s. Since then, many researchers have employed the original DBQ or a modified version, either to explore behavioral components (exploratory approach) or to confirm a given setting based on authors’ theories or observations, in group(s) under the study (confirmatory approach). Lack of exploratory analysis and spatial dispersion of respondents in the previous domestic researches, motivated the authors of this paper to conduct a new survey to investigate aberrant driving behaviors among Iranian drivers applying exploratory approach. The original DBQ was modified, validated and dispersed between Iranian drivers through an internet-based survey. Recent increase in the number of internet users in Iran, more interactions between respondants and the questionnaires, the power of self-administration, massive reductions in cost and time over interviewer-administered surveys, building a database, were among factors yielding hope that the sample would be comprehensive enough to comprise different groups of drivers. Using social networks and email services, the proposed questionnaire was exposed to internet users and a sample of 213 drivers (165 males and 48 females) from 40 cities inside and outside Iran, filled out the 37-item DBQ. Principal Component Analysis (PCA), with Varimax Rotation implied, a five-factor structure: “Push and Speed Violations”, “Disregarding the Regulations”, “Lack of Concentration while driving”, “Aggressive Violation” and “Lapses and Error” for Iranian drivers. These components account for 42.2 percent of the total variance. It is worth noting that the distinction between different kinds of violation and lapses and error support the fact that this new structure is consistent with the previous studies. Moreover, using cell phone while driving (both sending texts and talking), aggressive violations and push and speed violations are the most frequent aberrant driving behaviors. Compared to the other countries, drivers in Iran reported more violations than drivers in industrialized countries and fewer violations than Asian drivers. Results also show that unlike industrialized countries, Iranian drivers reported more aggressive violations than ordinary violations.}, Keywords = {Aberrant driving,Driver Behavior Questionnaire,Internet-Based Survey,Principal component analysis}, volume = {14}, Number = {1}, pages = {109-119}, publisher = {Tarbiat Modares University}, title_fa = {بررسی رفتار نابه جای رانندگان ایرانی با استفاده از پرسش نامه رفتار رانندگی؛ یک مطالعه اینترنتی}, abstract_fa ={سالیانه در ایران بیش از بیست هزار نفر در تصادفات رانندگی جان خود را از دست می دهند . عوامل انسانی در نیمی از تصادفات رانندگی، عامل اصلی و در بیش از نود درصد موارد، تأثیرگذار است     . در این مقاله با استفاده از پرسش نامه رفتار رانندگ ی، به بررسی عامل انسانی و تعیین ساختار رفتار نابه جای نمونه ای از رانندگان ایرانی پرداخته می شود     . با توجه به رویکرد تأییدی و پراکندگی مکانی اندک نمونه های مطالعه شده در ایران، در این مطالعه با استفاده از رویکرد اکتشافی و همچنین افزایش پراکندگی   جغرافیایی نمونه از طریق گردآوری داده ها در شبکه های اجتماعی و سرویس پست الکترونیکی، با استفاده از پرسش نامه رفتار   رانندگی توسعه یافته برای این مطالعه، ساختار رفتار نابه جای رانندگان ایرانی بررسی می شود     . نتایج تحلیل مؤلفه های اصلی، نشان می دهد که این ساختار در رانندگان ایرانی از پنج عامل     "سرعت و عجله"، "بی اعتنایی به قانون"، "عدم تمرکز"، "تخلفات خصمانه "   و "عدم توجه" تشکیل شده که 42 درصد از واریانس کل را تشکیل می دهند. مطالعه تطبیقی رفتار رانندگی، حاکی از آن است که رانندگان ایرانی، فراوانی تخلفات را بیشتر از رانندگان کشورهای توسعه یافته و کمتر از رانندگان کشورهای آسیایی اظهار کرده اند       .   هم چنین مقایسه فراوانی رفتار نابه جا نشان می دهد که رانندگان ایرانی، تخلفات خصمانه را بیشتر از تخلفات عادی، لغزش ها و خطاها مرتکب می شوند   .  }, keywords_fa = {رفتار نابه جا,پرسش نامه رفتار رانندگی,گردآوری اینترنتی,تحلیل مؤلفه های اصلی}, url = {http://mcej.modares.ac.ir/article-16-1835-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1835-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {MahinRoosta, R. and Jaafari, N.}, title = {Simulation of Anisotropy in Soft Rock Using a Multilaminate Model}, abstract ={Due to sedimentation process, structure of particles and subsequent loading history, most of the natural soil and rock deposits, tend to be highly anisotropic, which manifests itself in the directional dependence of deformation and strength characteristics. Also, existence of discontinuities such as joints and faults cause anisotropic behavior in the rock mass. Different constitutive models have been introduced by researchers to simulate the inherited or induced anisotropy in geo-materials. Due to the concept of the multi-laminate framework, in which yield and plastic potential functions are defined on a number of independent acting planes, plastic flow is developed independently on different planes. Therefore multi-laminate models are able to simulate induced anisotropy, intrinsically. In this study, a constitutive model based on multi-laminate framework with Mohr-Coulomb failure criterion for modeling the anisotropy is written and added to a two-dimensional explicit finite difference program, FLAC. In this model, anisotropy of geo-materials can be modeled in tow different ways; the first way is used to model jointed rocks with the assumption that a pronounced anisotropy of rock can be described by introducing a certain number of planes of weakness and behavior of rock mass can be determined from interaction of the joint planes and the intact rock. In the second way, anisotropy of sedimentary materials can be introduced in a straightforward manner by varying model parameters over the sampling planes that obtains by the parameters in the vertical and horizontal direction. When the number of plans is less than 5, geo-material is considered as the jointed rock mass with those number of joint sets, otherwise, geo-material considered as the sedimentary rock or soil mass; so application of different yield strength in numerous contact plane with uniform distribution, enable the model to simulate anisotropy in intact samples. For each contact plane, two failure criteria are considered associated with two potential functions. In fact non-associated flow rule and associated flow rule are applied to simulate plasticity formulations in shear and tensile mode of failure, respectively. Strength parameters of each contact plane are calculated based on its dip angle and the strengths of the intact soft rock in the direction of parallel and vertical to the sedimentation. The capability of the model is demonstrated by numerical simulation of uni-axial tests on jointed rock mass and the results are compared with those from analytical closed form solutions. The effect of anisotropy in friction angle and cohesion are investigated through the model in order to present sensitivity of the model to anisotropy ratio and angle of sedimentation. Finally the proposed model is used to simulate stability of a slope in the sedimentary domain; the results show that with a constant sedimentation angle, increase in anisotropy ratio will increase the differences of the safety factor of the slopes with isotropic and anisotropic behavior.}, Keywords = {Anisotropy,Shear Strength,Multi-Laminate Model,Joint,Sedimentary soft rock}, volume = {14}, Number = {1}, pages = {121-133}, publisher = {Tarbiat Modares University}, title_fa = {شبیه سازی ناهمسانی در سنگ نرم با استفاده از یک مدل چندصفحه}, abstract_fa ={چکیده - به خاطر ساختار ذر هها فرایند رسوبگذاری و بارگذاری های متعاقب، مصالح ژئوتکنیکی از خود رفتار ناهمسانی نشان می دهند . در این مقاله تاثیر ناهمسانی در رفتار برشی توده سنگ نرم بررسی م ی شود . ازین رو مدلی در چارچوب مد ل های چندصفحه ارائه شده است که رفتار تغییر شکل توده را به وسیله ی پاسخ روی چندین صفحه تماسی بیان م یکند     . سطح تسلیم، قانون جریان و سخت شوندگی، روی صفح هها فرمول بندی شده و ناهمسانی مواد رسوبی با در نظرگرفتن ویژگی های مقاومتی مختلف،   روی صفحات فرضی مدل چن دصفحه، شبیه سازی می شود     . اگر تعداد صفحات از حدی کمتر باشد، از مدل ارائه شده می توان برای شبیه سازی توده سنگ درزه دار بهره برد     . درحالی که با ارائه توابع تسلیم متفاوت روی تعداد زیادی از صفحات با پخش یکنواخت ، اضافه شده و پس از     Flac رفتار سنگ نرم رسوبی، ناهمسان است. مدل چند صفحه به صورت مدل رفتاری به نر مافزارتفاضل محدود بررسی درستی آن با روش حل بسته، از آن برای شبیه سازی رفتار ناهمسان یک نوع سنگ رسوبی استفاده شده است     . در نهایت، شبیه سازی پایداری شیروانی از مصالح ناهمسان ارائه است       .  }, keywords_fa = {ناهمسانی,مقاومت برشی,مدل چند صفحه,درزه,سنگ نرم رسوبی}, url = {http://mcej.modares.ac.ir/article-16-8233-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-8233-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Noorbalhsh, F. and MajdzadehTabatabai, M.R. and Kharazifard, M.H.}, title = {Experimental Investigation of Scour Hole Length and Reynolds number variations under Different Bank Slopes in Rivers}, abstract ={River bank erosion causes damages to agricultural land, adjacent establishments and widening of river dimensions. Mass failure process of bank erosion is a factor to transport bulk of sediments followed by deposition in downstreams of a river system, which could be an important problem in river management. This research is to investigate internal erosion under different bank and floodplain slopes, By this means, a number of experiments were carried out in a model designed to simulate internal river bank erosion in the laboratory. In these experiments, the scour hole length, resulted from internal erosion and seepage discharge were measured under different hydraulic gradients. Results showed that bank slope plays an effective role in scour hole length and calculated Reynolds number in porous medium. As it was observed that the scour hole length and hydraulic gradient decrease with an increase in the bank slope and porous medium Reynolds number decreases with reduction in the hydraulic gradient.}, Keywords = {Internal erosion,Rivers Bank slope,Scour hole length,Reynolds number}, volume = {14}, Number = {1}, pages = {135-145}, publisher = {Tarbiat Modares University}, title_fa = {بررسی آزمایشگاهی تغییرات عمق آبشستگی ناشی از فرسایش درونی در کناره ی رودخانه ها}, abstract_fa ={فرسایش سواحل آبراهههای جریان باعث خسارت به اراضی مستعد کشاورزی، تأسیسات کناری و پهن شدن آبراهه ی جریان میشود. فرایند فرسایش تودهای ساحل رودخانه عاملی برای انتقال حجم بزرگ رسوب با پیامدهای رسو بگذاری در پایین دست یک سیستم رودخانه بوده و مسئلهی مهمی در مدیریت رودخانه است. این پژوهش با هدف بررسی فرسایش درونی تحت سه شیب کناره در رودخانهها و دو شیب لایههای آبرفتی انجام شده است. بدین منظور آزمایشهایی روی یک مدل آزمایشگاهی برای اندازه گیری عمق آبشستگی ناشی از فرسایش درونی و اندازه گیری دبی خروجی برای محاسبه عدد رینولدز به عمل آمده است. مدل آزمایشگاهی مورد استفاده دارای طول 50 سانتی متر، عرض 20 سانتی متر و ارتفاع 50 سانتی متر است . مصالح مورد استفاده در 1 میل یمتر و لایه ی سوم به /2-2/ 0 و 0 /8-1/2 ،0/4-0/ مخزن شامل رس به عنوان لایه چسبنده، ماسه با سه دانهبندی متفاوت 8 عنوان سربارمیباشد. این آزمایشها در ارتفاع آبی متفاوت و تحت گرادیانهای هیدرولیکی متفاوت انجام شد. نتایج نشان داد که میزان شیب کناره در عمق آبشستگی و عدد رینولدز مؤثر است. با افزایش شیب کناره میزان عمق آبشستگی و گرادیان هیدرولیکی کاهش پیدا می کند و با کاهش گرادیان، عدد رینولدز کاهش پیدا میکند.}, keywords_fa = {فرسایش درونی,شیب کناره رودخانه,میزان طول پسروی,عدد رینولدز}, url = {http://mcej.modares.ac.ir/article-16-1611-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1611-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Ouhadi, V.R. and PourZafarani, M.}, title = {Influence of Temperature on Unconfined Compressive Strength and Water Absorption of Sand-Bentonite Mixture in the Presence of Carbonate}, abstract ={influenced by temperature. On the other hands, the existing of carbonate as one of the major components of clayey soils in arid and semi-arid lands, and its effect on engineering properties of the soils prove the necessity to study the simultaneous influence of carbonate and temperature on the engineering behavior of clayey soils. In the present work, the interaction between clay and carbonate in high temperatures has been investigated. Bentonite were mixed with different percentages of carbonate and sand. The variations of added carbonate were 0% (natural carbonate content), 10%, 20%, and 30%, respectively, and added sand were 20% and 40%. The soil samples were carefully mixed with enough water to bring them to their plastic limit and were kept in plastic bag for uniform-moisture distribution for a period of 24 h. It was then sieved through a #10 mesh to ensure to achieve a uniform mixture. Samples for testing were then prepared by compacting soil mixtures into cylinder mold in three layers. The test specimen dimensions were 35 mm in diameter and 70 mm in height. The clay specimens were allowed to air dry at room temperature for 24 h. Bentonite specimens were kept in plastic bag to prevent development of cracks during air drying due to high crack potential. The samples were then oven dried at 110 °C for a period of 24 h. The test specimens were heated to temperatures of 300, 500, 700, 900 and 1100 °C, using programmable Carbolite electric furnace. The specimens were placed in the electric furnace at room temperature and then the temperature was increased at a rate of 3 °C/min until the desired temperature was reached. Once the treatment temperature was reached, it was held at that stage for 2 h, then the furnace was turned off. The specimens were then allowed to cool overnight in the closed furnace. After this curing condition, samples with different levels of temperature including 25 °C (laboratory temperature), 110, 300, 500, 700, 900 and 1100 °C were used for experiments. The changes of physical and engineering properties of the soil were studied by performing macro-structural tests such as linear shrinkage, water absorption and unconfined compression. The results show that as temperature increases close to the de-hydroxylation temperature, strength gradually increases. At de-hydroxylation temperature, the strength significantly increases, so that the strength of bentonite specimens increases 3 to 4 times. The strength of bentonite specimens significantly decreased with increasing the heat over de-hydroxylation temperature. This strength reduction was due to the formation of microscopic voids and pores in the specimen. Analyzing the simultaneous influence of carbonate percentage and heating indicate that the increase of carbonate percentage in a given temperature results in the decrease of strength and the amount of this reduction is different in different temperatures. In bentonite specimens, heating causes the water absorption to be decreased, however, the increase of carbonate percentage results in the increase of water absorption in a given temperature. Temperature, Bentonite, Calcium carbonate, water absorption, Unconfined compressive strength.}, Keywords = {temperature,Bentonite,Calcium carbonate,Water Absorption,Unconfined compressive strength}, volume = {14}, Number = {1}, pages = {147-157}, publisher = {Tarbiat Modares University}, title_fa = {تأثیر حرارت بر مقاومت فشاری محدود نشده و میزان جذب آب مخلوط ماسه ‒ بنتونیت در حضور کربنات}, abstract_fa ={مشخصات خاک ها به ویژه کانی های ناشی از هوازدگی شیمیایی از جمله خاک های رسی ب هشدت متأثر از حرارت است   .   این موضوع در کنار وجود کربنات به عنوان یکی از اجزای اصلی خاکهای رسی، به ویژه در مناطق خشک و نیمه خشک، می تواند موجب تغییر در رفتار مهندسی خاک شود . در پژوهش حاضر تأثیر حرارت بر فرایند اندرکنش مخلوط ماسه - بنتونیت و کربنات کلسیم با استفاده از آزمایش های مختلف از جمله انقباض خطی، مقاومت فشاری محدود نشده و جذب آب ، مورد ارزیابی قرار     20 و 30 درصد کربنات به همراه 20 و 40 درصد ماسه با بنتونیت ترکیب و در معرض ،10 ، گرفته است. بدین منظور مقادیر 0   سطوح حرارتی متفاوت بین 25 تا 1100 درجه سانتی گراد قرار داده شدند. نتایج نشان دهنده آن است که افزایش حرارت سبب افزایش مقاومت نمونه ها تا دمای دی هیدروکسیلاسیون شده ولی در حرارت های بیش از دما ی دی هیدروکسیلاسیون ، مقاومت به   میزان قابل ملاحظه ای کاهش یافته است     . از سوی دیگر، افزایش درصد کربنات در یک دمای مشخص، باعث کاهش مقاومت و انقباض خطی شده است     . همچنین تغییرات جذب آب نمونه ها، در اثر افزایش حرارت، تابعی از درصد کربنات موجود در خاک و محدوده حرارت اعمال شده است       .  }, keywords_fa = {حرارت,بنتونیت,کربنات,مقاومت فشاری محدود نشده,جذب آب}, url = {http://mcej.modares.ac.ir/article-16-2365-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2365-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Radaei, E. and AlaviMoghaddam, M.R. and Arami, M.}, title = {Optimization of Reactive Blue 19 adsorption from aqueous solution by pomegranate residual-based activated carbon using Taguchi method}, abstract ={Dyes are being extensively used in textile, dyeing and leather industries and usually have a synthetic origin and complex chemical structure that may be mutagenic and carcinogenic. Among various processes of dye removal from wastewater, adsorption is considered to be the most efficient process. Activated carbon is the most widely used adsorbent with great success because of its high adsorption capacity, but its use is limited due to its high-cost, has led to a search for cheaper substitutes. Optimization methods, such as the Taguchi method has been generally adopted to optimize the design parameters, because this systematic approach can significantly minimize the overall testing and the experimental costs. In this study; the optimum condition of Reactive Blue 19(RB19) removal by activated carbon based on pomegranate residual is determined using Taguchi method. For this purpose, 4 main factors such as pH, adsorbent dose, initial dye concentration and contact time were considered in 5 levels. Therefore, an L25 orthogonal array was chosen, and the experimental conditions were obtained. In addition, after design of experiments, an analysis of the signal-to-noise (S/N) ratio was needed to evaluate the experimental results. The analysis of mean (ANOM) statistical approach was adopted herein to construct the optimal conditions. In addition to ANOM, the analysis of variance (ANOVA) statistical method was also used to analyze the influence of each controllable factor on the dye removal efficiency. To prepare the To prepare the activated carbon (AC), pomegranate residual was collected. Collected sample has been dried in an oven for 2 h at 100 0C. It was then ground in a ball mill and the material passed through the No.30 mesh was collected and tested. They were soaked for 24 h in a 1:1 wt. ratio with 50 wt. % phosphoric acid as the carbonized at room temperature. The sample is then decanted and dried in a muffle furnace for 1 h at 500 0C. They were then washed sequentially several times with hot distilled water, until pH of the washing solution became neutral. AC was finally powdered and sieved by the No. 100 mesh. The experiments were done 3 times according to the tests conditions determined by the Taguchi method and the dye removal efficiency was measured. Due to the results of S/N and ANOM, it can be inferred that the optimum mixture proportions to obtain the highest RB19 removal efficiency are as follows. (1) Initial dye concentration of 100 mg/L; (2) pH of 11; (3) adsorbent dose of 1.75 gr/L; and (4) contact time of 7 minutes. The experiment with aforementioned condition was done and result was shown the highest efficiency (98.94%). According to the result of ANOVA, the rank order of the contribution percentage of each factor on RB19 removal efficiency is as follows: (1) initial dye concentration (52.67%), (2) adsorbent dose (33.32%), (3) pH (13.61%), and (4) contact time (2.72%).}, Keywords = {Adsorption,Taguchi,Reactive Blue 19,pomegranate residual,Analysis of Variance}, volume = {14}, Number = {1}, pages = {159-167}, publisher = {Tarbiat Modares University}, title_fa = {از محلول آبی Reactive Blue بهینه سازی جذب رنگ 19به وسیله ی کربن فعال پسماند انار با استفاده از روش تاگوچی}, abstract_fa ={به وسیله ی کربن فعال برپایه پسماند Reactive Blue 19(RB چکیده- هدف از انجام این پژوهش، تعیین شرایط بهینه حذف رنگ (  انار با استفاده از روش طراحی تاگوچی است. چهار عامل اصلی شامل 9 دقیقه) به عنوان فاکتورهای موثر در راندمان حذف در نظر گرفته شدند که - 500 میلیگرم بر لیتر) و زمان تماس( 1 - اولیه رنگ( 100 غلظت جاذب، غلظت اولیه ،pH برای هر کدام 5 سطح تعیین شد. بر اساس نتایج حاصل از این روش، بیشینه ی بازدهی حذف در 1گرم بر لیتر، 100 میلیگرم بر لیتر و 7 دقیقه به دست آمد. برای تعیین اثر گذاری هر /75 ، رنگ و زمان تماس به ترتیب برابر 11 عامل در حذف رنگ از آنالیز واریانس استفاده شد. بر این اساس، غلظت اولیه رنگ و زمان تماس به ترتیب بیشترین و کمترین اثر را داشتهاند. نتایج بدست آمده نشانگر عملکرد بالا و سریع کربن فعال حاصل از پسماند انار در حذف RB بر بازدهی حذف رنگ 19 از محلول های آبی است}, keywords_fa = {Reactive Blue واژگان کلیدی: جذب,تاگوچی,رنگ 19پسماند انار,آنالیز واریانس}, url = {http://mcej.modares.ac.ir/article-16-8083-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-8083-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Alizadeh, T. and Moradloo, J. and Moradloo, J.}, title = {Numerical simulation of impact penetration in concrete target and investigating of empirical solution}, abstract ={Understanding the behavior of concrete at high strain rates loading is a critical issue for theory and applied purposes. The concrete is non-linear, rate-sensitive and pressure-dependent material that will add more difficulties in its modeling at high loading conditions such as impact penetration situations. In the present study, numerical simulation of penetration in a concrete target using an advanced plasticity concrete model is presented using explicit finite element (FE) analysis. A full 3D FE model of impact on unreinforced concrete specimens is carried out. The analysis includes initiation and progressive damage of the composite during impact and penetration Also comparison between some empirical solutions is carried out and their accuracy and precision are checked used experimental solution. Concrete nonlinear behavior was modeled using RHT model which is an advanced plasticity model for concrete at high strain rate loading condition. Two test examples are presented to demonstrate the proposed method. They involve the impact of an ogive-nose projectile on concrete cylinders with variable dimensions. The FEM computational results obtained using RHT plasticity model are very close to the test data, implying that the proposed method will be promising in studies of impact analyses of concrete structures subjected to impact loading. In using RHT model with the default model parameter values, the experimental results cannot be reproduced satisfactorily. Deduced results having good agreement withexperimental ones using suitable calibration of plasticity model parameters value. The RHT plasticity concrete model was developed as an enhancement to the JH concrete model by the introduction of several new features. In this new model, the strain hardening and the third invariant dependence were considered. An independent fracture strength surface was incorporated to allow for a more appropriate modeling of the material softening response. In addition, the concrete hydrostatic tensile strength was made rate dependent. Using a modified parameter setting, the RHT model implemented in AUTODYN hydrocode exhibits a generally excellent behavior. In this paper also, a comprehensive evaluation study of several widely used empirical penetration depth relation is presented. The model formulations are scrutinized and numerical tests are carried out to examine their actual performances subjected to various loading conditions. Comments on the limitations and the appropriate use of these models are given. In addition to penetration depth, damage extension, concrete sapling, scabbing and output velocity of missile and other time dependent structural quantities can captures well. This is in contract with imperial relations that have only penetration depth calculation capability for special conditions. On the other hand investigating of empirical relation shown in addition to their finite application ranges, they haven't good results in majority of cases. Among them, US army corps of engineers'' experimental based relation have better results compared other empirical relations for calculation of penetration depth.}, Keywords = {Concrete penetration,empirical relation,Numerical solution,Impact,nonlinear solution,RHT plasticity model}, volume = {14}, Number = {1}, pages = {169-179}, publisher = {Tarbiat Modares University}, title_fa = {شبیه سازی عددی نفوذ پرتابه در هدف بتنی و بررسی روابط تجربی نفوذ}, abstract_fa ={در این پژوهش رابطه ی تجربی و تحلیلی معتبر که برای محاسبه عمق نفوذ ب وسیل هی پژوهشگران ارائه شده، به همراه روش شبیه سازی عددی به وسیله نتایج تعدادی از آزمایش های تجربی بررسی و مقایسه شد . با مقایسه نتایج روابط تجربی و آزمایشگاهی می توان عنوان کرد که این روابط براساس نتایج حاصل از آزمایش های تجربی و در محدوده کاربری خاصی نتیجه گیری شده و دارای دقت مناسبی در بیشتر موارد نیست. از میان روابط تجربی ارائه شده رابطه گروه مهندسین ارتش آمریکا دارای که یک مدل ،(RHT) عملکرد و دقت مناسبتری نسبت به دیگر روابط است. در بحث شبی هسازی عددی با استفاده از مدل آر.اچ تی مقاومت و شکست بتن پلاستیسیته پیشرفته است، دو شبیه سازی عددی انجام شده که نتایج این دو و نتایج حاصل از روابط تجربی با نتایج آزمایشگاهی مقایسه شده است. نتایج این مطالعه نشان می دهد که با دقت مناسب پارامترهای مدل ماده استفاده شده در شبیه سازی عددی، می توان به نتایجی با دقت رسید.}, keywords_fa = {مدلسازی نفوذ در بتن,روابط تجربی,شبیه سازی عددی,ضربه,تحلیل غیرخطی}, url = {http://mcej.modares.ac.ir/article-16-5116-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-5116-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Mahmoudi, M. and JavadianFard, S.}, title = {Introduction of “Modified Response Modification Factor Method” for Structural Seismic Design}, abstract ={The traditional procedure for seismic design of building structures has been generally termed the force-based design (FBD) method. In the FBD method, the elastic seismic force acting on the structure is calculated first with the aid of a design acceleration response spectrum. This elastic force is then divided by a reduction factor called behavior factor R, representing the ductility and overstrength capacities of the structures. The implementation of FBD in seismic codes, does not clearly define the performance level. Furthermore, this method assumes the constant behavior factor values for the structures with the similar types of the lateral load resisting systems and do not take into account structure numeral properties same as the influence of the number of stories. These are some disadvantages of the FBD method that have been referred in many researches. So recently, procedures have been developed to substitute for this method. The design procedure would be more rational if the performance of the structure was quantified through a target value of deformation treated as an input variable in the design procedure. This target value of deformation can be assigned to different performance objectives and is the starting point for the development of the rather new displacement-based seismic design (DBD) method and is described in the some guidelines and publications as a performance-based seismic design method. The third and newest seismic design method is called the hybrid force/displacement-based design (HBD) method that adopts the seismic design philosophy based on both the resistance performance-based seismic design method. The third and newest seismic design method is called the hybrid force/displacement-based design (HBD) method that adopts the seismic design philosophy based on both the resistance and the performance. The HFD method combines the best elements of the FBD and DBD methods and tries to avoid those ones, which are usually thought of as disadvantages. This research proposes a new hybrid force/displacement-based seismic design method that is named the modified behavior factor (MBF) method. The MBF method combines the FBD method of the Iranian Earthquake Resistance Design Code (Standard No. 2800) and the DBD method of the Iranian Instruction for Seismic Rehabilitation of Existing Buildings (Publication No. 360). Two 5 and 7 story frames with three bays have been seismically designed by the MBF and the FBD methods and the results of them have been compared. The seismic responses of the MBF method are more precise than the responses of the FBD method.}, Keywords = {Performance-based seismic design,Force-based design,Displacement-based design,Hybrid-based design,The modified response modification factor method}, volume = {14}, Number = {1}, pages = {181-193}, publisher = {Tarbiat Modares University}, title_fa = {طراحی لرزه ای سازه ها با استفاده از "روش ضریب رفتار اصلاح شده"}, abstract_fa ={چکیده - در حال حاضر، در طراحی لرزهای سازهها از دو روش نیرویی و تغییرمکانی استفاده می شود. اخیراً محققان با ترکیب اجزای دو روش نیرویی و تغییرمکانی، روش سومی با عنوان روش طراحی لرزهای مرکب معرفی کردهاند . هدف از ارائه این مقال ه، است که از ترکیب روش نیرویی استاندارد     2800 و روش « روش ضریب رفتار اصلاحشده » معرفی یک روش مرکب جدید با نام تغییرمکانی نشریه     360 حاصل می شود. در این روش، ضریب رفتار با مشاهده رفتار واقعی سازه و بهره گیری از تحلیل استاتیکی غیرخطی     (تحلیل پوشاور) تعیین میگردد. برای ارزیابی روش پیشنهادی، دو قاب فولادی 5 و 7 طبقه، به دو روش نیرویی استاندارد   2800 و روش مرکب ضریب رفتار اصلاح شده، طراحی شده و پاسخ های مختلف آنها مورد مقایسه قرار گرفته است. به دلیل اینکه در بسط تئوری روش مرکب پیشنهادی، از معایب روشهای نیرویی و تغییرمکانی پرهیز شده است، پاسخ های لرزه ای همچون برش   پایه طرح و تغییرمکان غیرارتجاعی سازه در این روش با دقت بیشتری تعیین می شود       .  }, keywords_fa = {روشهای طراحی لرزهای,روش نیرویی,روش تغییرمکانی,روش مرکب,روش ضریب رفتار اصلاحشده}, url = {http://mcej.modares.ac.ir/article-16-4228-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-4228-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {emami, ebrahim and Kheiroddin, Ali and Sharbatdar, mohamm}, title = {Investigation of Steel Curb Effect on Nonlinear Behaviour of Reinforced Concrete Frames With Finite Element Method}, abstract ={It is required to rehabilitate the existing structures due to many reasons including the retrofitting of damaged structures under earthquakes or the need to strengthen or retrofit an undamaged structure designed based on old building codes. So, the rehabilitation and retrofit of structures against seismic loads is unavoidable. This paper presents the results of a nonlinear finite element analysis of an ordinary reinforced concrete frame and also strengthened frame by steel prop and curb under monotonic lateral load. The effect of steel prop on linear and nonlinear behavior of reinforced concrete frame and also increasing the rigidity, ultimate strength, rate of energy absorption and ductility parameter of frame are investigated. The experimental results of a one-bay and one-story reinforced concrete frame are considered and after calibrating the numerical results against it, the mentioned parameters have been investigated. Numerical results show that using steel curb and prop box in compression and tension state with 5,7.5,10 cm2 area in frame will considerably increase the rigidity, ultimate strength and decrease the ultimate displacement of frame. Furthermore, the yielding of steel prop as a preliminary defensive system against lateral loads will increase the energy absorption and ductility and also will decrease the stresses in panel zone.}, Keywords = {Rehabilitation,RC frame,Steel Curb,Prop Box,Finite Element}, volume = {14}, Number = {3}, pages = {1-15}, publisher = {Tarbiat Modares University}, title_fa = {بررسی تاثیر دستک فلزی بر رفتار غیر خطی قابهای بتن آرمه به کمک روش المان محدود}, abstract_fa ={به دلایلی ممکن است سازه های موجود نیاز به بهسازی داشته باشند که این عمل، شامل احیاسازی سازه های آسیب دیده توسط یک زلزله یا عوامل دیگر، یا مقاوم سازی و تقویت یک سازه خسارت ندیده که با آیین نامه های بارگذاری و طراحی ویرایش قدیم یا حتی بدون کد، طراحی و ساخته شده اند، می شود، لذا بهسازی سازه های مقاوم در برابر زلزله امری ضروری بنظر می رسد. در این مقاله نتایج تحلیل غیر خطی المان محدود یک قاب بتن آرمه معمولی و همچنین تقویت شده با دستک و طوقه فلزی، تحت بار جانبی افزاینده نشان داده می شود. تاثیر دستک فلزی بر رفتار خطی و غیر خطی قاب بتن آرمه و همچنین افزایش سختی، مقاومت نهایی و میزان جذب انرژی و شکل پذیری قاب مورد بحث قرار می گیرد. نتایج آزمایشگاهی یک قاب بتن آرمه یک دهانه یک طبقه انتخاب شده و پس از کالیبراسیون مدل عددی و اطمینان از صحت و دقت نتایج، پارامترهای مذکور بررسی می شوند. نتایج تحلیل کامپیوتری نشان می دهد که استفاده از طوقه و دستک فلزی بصورت فشاری و کششی با مساحت 5 ‏‏, 5/7 و10 سانتیمتر مربع در قاب مورد نظر، باعث افزایش قابل توجه سختی و مقاومت نهایی و کاهش تغییر مکان نهایی قاب بتن آرمه می شود. همچنین دستک با جاری شدگی خود به عنوان سیستم دفاعی اول در برابر بارهای جانبی، می تواند مانند فیوزی، جذب انرژی و میزان شکل پذیری را افزایش دهد و تنشهای ناشی از بار جانبی را در اطراف چشمه اتصال کاهش دهد.}, keywords_fa = {مقاوم سازی- قاب بتن آرمه- دستک- طوقه فلزی- المان محدود}, url = {http://mcej.modares.ac.ir/article-16-11187-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11187-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Ouhadi, Vahi}, title = {Lead Retention of Carbonated Kaolinite in the Adsorption and Electrokinetics Processes}, abstract ={Electrokinetics is a common and practical method for contaminant removal from fine grain soils. In spite of several researches performed on the factors affecting the application of electrokinetics method for contaminant removal from soils, there are still extensive attentions of researches on the influence of soil components on the efficiency of this method upon contaminant removal. The main objective of this research is to investigate on the impact of carbonate elimination and contaminant concentration on the Pb removal from carbonated kaolinite in electrokinetics process. To achieve this objective a natural kaolinite sample which had 4% natural carbonate and a carbonate eliminated kaolinite were laboratory contaminated with 5 and 20 cmol/kg-soil of lead nitrate. After achieving equilibrium, the laboratory contaminated samples were dried in oven at 40 centigrade temperature for 96 hours. Then, 27% water was added to samples as initial water content. To achieve homogeneous distribution of water content, the sample was kept in a plastic bag for 24 hours. Then sample was passed through #10 sieve to have a more homogeneous sample. Finally, the soil sample was compacted in five layers at dry density of 1.7 g/cm3 in the electrokinetics cell. Then, the electrokinetics method was performed on these samples for contaminant removal. Electrokinetics experiments performed for a 240 hours period. After the end of experiment, the soil sample was taken from cell and sectioned in 5 slides. Each slice was analyzed for water content, soluble and adsorbed contaminant. In addition to electrokinetics experiment, buffering capacity test was performed by titration of soil sample with nitric acid. For this purpose, the diluted nitric acid in 1:10 soil:acid solution was added to sample. The soil solution sample kept on the shaker for 96 hours. After equilibrium the pH of soil solution was measured. This experiment was performed for different concentration of nitric acid. The final type of experiment include batch equilibrium experiment in which different concentrations of 5, 10, 20, and 30 cmol/kg-soil of lead nitrate was prepared. Then 20 milligram of each solution was added to 2 grams of kaolinite sample. After the shaking period and centrifuging the sample, the pore fluid was analyzed to measure the soluble and retained heavy metal. The results of experimental study indicate that the reduction of carbonate in carbonate rich kaolinite and an increase in contaminant concentration causes a reduction in soil buffering capacity. This means that as the concentration of carbonate in soil sample decreases, one faces with a reduction in contaminant retention capacity of soil. In addition, in such a case a reduction in pH happens which consequently enhances the contaminant removal from soil. Furthermore, carbonate elimination causes an increase in contribution of electro-osmosis on soil improvement which is followed by water content variation and consolidation of soil.}, Keywords = {Electro-Osmosis,Electrokinetics,kaolinite,Carbonate,Contaminant Removal}, volume = {14}, Number = {3}, pages = {17-30}, publisher = {Tarbiat Modares University}, title_fa = {مطالعه نگهداشت آلاینده سرب در نمونه‌های کائولینیت حاوی درصدهای مختلف کربنات طی فرایندهای جذب و الکتروسینتیک}, abstract_fa ={در مهندسی ژئوتکنیک زیست¬محیطی، الکتروسینتیک به عنوان روشی کارآمد در رفع انواع آلودگی¬ها از خاک¬های ریزدانه مورد استفاده قرار گرفته¬است. هرچند که محققان زیادی به¬منظور رفع آلودگی از خاک¬ها از روش الکتروسینتیک استفاده نموده¬اند اما هنوز تأثیر اجزاء خاک بر بازده این روش توجه محققین بسیاری را به خود جلب کرده¬است. در مناطق خشک و نیمه خشک جهان از جمله ایران، کربنات¬ها یکی از اجزاء اصلی بسیاری از خاک¬ها می¬باشند. همچنین کربنات¬ها به عنوان یکی از عوامل اصلی افزایش خاصیت بافری خاک شناخته شده¬اند. کربنات¬ها در مقایسه با سایر مکانیسم¬ها مانند فاز تبادلی، مواد آلی و مواد آمرف بیشترین نقش را در نگهداشت فلزات سنگین ایفاء می¬کنند. علیرغم تحقیقاتی که در این زمینه صورت گرفته¬است به موضوع نگهداشت آلاینده فلزسنگین در نمونه¬های حاوی درصدهای مختلف کربنات طی فرایند جذب و الکتروسینتیک توجه کمتری شده¬است. پژوهش حاضر با هدف تعیین تأثیر کربنات¬زدائی و میزان غلظت اولیه آلاینده بر رفع فلز سنگین سرب (Pb) از کائولینیت کربنات¬دار در فرایند الکتروسینتیک انجام شده¬است. در این راستا نمونه¬های کائولینیت حاوی 4% کربنات طبیعی، و نمونه¬های کربنات¬زدائی شده با دو غلظت 5 و 20 سانتی مول بر کیلوگرم- خاک آلاینده سرب مورد آزمایش رفع آلودگی به روش الکتروسینتیک قرار گرفتند. نتایج این تحقیق حاکی از آن است که کاهش کربنات در کائولینیت کربنات¬دار، سبب کاهش در ظرفیت بافرینگ، پایین بردن pH، کاهش قابلیت نگهداری یون¬های فلزات سنگین و در مجموع افزایش بازده رفع آلودگی می¬شود. همچنین مکانیسم الکترواسمزی نیز در اصلاح رفتار خاک عمل نموده و تغییرات درصد رطوبت و تحکیم در نمونه¬ها مشاهده می¬شود.}, keywords_fa = {الکترواسمزی,الکتروسینتیک,کائولینیت,کربنات,رفع آلودگی خاک}, url = {http://mcej.modares.ac.ir/article-16-6710-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6710-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {1, 1 and Farsijani, Ali}, title = {The effect of moisture content on the shear strength parameters of plastic fine soils}, abstract ={The effect of matric suction on shear strength of soil, because of its dominant role in geotechnical modelling, has received the attention of researchers in this filed. This research is focused in investigating the effect of matric suction on shear strength of a fine soil. The physical properties of the soil are determined. All samples are passed through No. 200 sieve. The soil is a high plasticity soil which is classified CH according to the unified classification system. The filter paper method is performed to extract the soil water characteristic curve. In addition to its simplicity, one of the major advantages of this method is the vast range of suctions can be measured by it. Specimens were compacted at identical void ratio with different water contents. Suctions are inferred from empirical relations that relate the suction to the measured moisture content of filter paper which has been in contact with soil sample. Air entry suction is determined 140 kPa from SWCC curve. In order to examine moisture content effects on shear strength parameters (cohesion and friction angle) of the clay, soil samples are prepared with different moisture content and consequently different matric suctions with respect to soil water characteristic curve. The specimens with different initial moisture contents are statically compacted at dry density of 1.3 gr/cm3into direct shear test mould. The moisture contents of samples are in the range of 10 to 28 precent. Hence, according to soil water characteristic curve the initial matric suctions are between 42 to 25238 kPa. Direct shear tests are conducted in unsaturated state. After applying vertical stress the samples are left at least for 48 hours to allow the equalization of internal stresses. Based on experimental data the shear stress is plotted against horizontal displacement in different vertical stresses and moisture contents and the results and analysed and discussed. The effective stress equation proposed by Bishop (1959) is used to interpret the results. The effective stress parameter χ in each moisture content is calculated bythe equation suggested by Khalili & Khabbaz (1998) using the air entry suction extracted from SWCC curve. The results reveal that strength parameters do not substantially change at different moisture contents. The negligible changes in strength parameters may be attributed to slight changes in pore water pressure during shearing experiment. Such changes in pore pressure during shearing would be eliminated in constant suction consolidated drained experiments. The results of this paper support the validity of effective stress concept in unsaturated soils. In other words, with a proper estimate of effective stress, the saturated parameters are valid in unsaturated state and it is not necessary to measure strength parameters in unsaturated state. The unsaturated geotechnical experiments are time consuming and expensive and need special equipment and skills. The method proposed in this paper has a good degree of accuracy. Therefore it can decrease the costs of geotechnical investigation projects in arid lands.}, Keywords = {Initial water content,Cohesion,internal friction angle,plastic soil,filter paper method}, volume = {14}, Number = {3}, pages = {31-41}, publisher = {Tarbiat Modares University}, title_fa = {تأثیر رطوبت بر پارامترهای مقاومت برشی خاک های ریزدانه خمیری}, abstract_fa ={تأثیر مکش بافتی بر رفتار برشی خاک ریزدانه از آن جهت که نقش تعیین کننده ای در مدلسازی ژئوتکنیکی دارد، همواره مورد توجه محققین در این زمینه بوده است. در این پژوهش به تأثیر مکش بافتی بر پارامترهای مقاومت برشی خاکهای ریزدانه پرداخته شده است. برای مشاهده تأثیر مکش بافتی بر پارامترهای مقاومت برشی (چسبندگی و زاویه اصطکاک داخلی) ، نمونه هایی از یک خاک ریزدانه خمیری با درصد رطوبت اولیه و در نتیجه مکش های بافتی متفاوت، بر اساس منحنی مشخصه آب- خاک و منحنی تراکم ساخته شدند. نمونه های خاک بر اساس شرایط اولیه مورد نظر در جعبه دستگاه برش مستقیم بصورت استاتیکی متراکم شدند. بر روی نمونه های آماده شده آزمایش برش مسقیم در حالت غیراشباع صورت گرفت. بر اساس نتایج آزمایشها، منحنی تغییرات تنش برشی بر حسب جابجایی افقی در تنش های قائم متفاوت رسم شد و درباره نتایج آن بحث گردید. نتایج نشان داد که تغییرات میزان رطوبت و در نتیجه تغییرات مکش بافتی اولیه نمونه های خاک، تأثیر قابل توجهی بر پارامترهای مقاومت برشی خاک غیراشباع ندارد.}, keywords_fa = {رطوبت اولیه,چسبندگی,زاویه اصطکاک داخلی,خاک خمیری,فیلتر کاغذی}, url = {http://mcej.modares.ac.ir/article-16-3446-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-3446-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Paseh, Hamidreza and Yazdani, Mahmood and Sharifzadeh, Mostaf}, title = {Evaluation and Improvement of Contact Detection Algorithms for Using in DEM in Rock Mechanics}, abstract ={Discrete Element Method (DEM) is a numerical method for computing the motion and effect of a large number of small particles. It is a very common method to solve rock mechanics problems, since it can solve problems containing particles in contact with complicated geometries efficiently. Contact detection is the most time consuming (so the most significant) part of DEM-based problem solving methods. In this article, authors, with the goal of implementing a numerical hydro-mechanical software to analyze and solve DEM rock mechanics problems (DA2), studied and investigated algorithms able to solve contact detection problem. The most algorithms designed to find contacts (contact detection algorithms), lie in two classes: 1) algorithms based on bounding boxes, and 2) algorithms based on hashing. The bounding box idea helps to simplify the contact detection problem and to prevent dealing with particle shapes by enveloping the whole particle in a shape (generally a rectangle or an ellipse) which is easy to check for finding overlaps. Since overlaps of bounding boxes may not directly result in contacts between particles, further checks are needed. In the former class, there are two well-known published algorithms, both based on sorting bounding boxes’ extents, able to find contacts between generally shaped particles in a fast and efficient way: incremental sorting and updating (ISU) algorithm, and double-ended spatial sorting (DESS) algorithm. Hashing algorithms are generally appropriate for particles with uniform sizes. Since rock mechanics problems mostly contain models constituted of blocks with non-uniform sizes, hashing algorithms are not utilized for solving them. In this article, ISU and DESS algorithms along with direct checking (DC) method are compared for their running time results to find the most appropriate (i.e. the fastest) algorithm to find contacts between rock blocks. For this purpose, algorithms were implemented by DA2 software, then, ran in the same environment and for same commonplace geomechanical problems with varying model parameters, like number of blocks, block size variation, angle of discontinuities and friction angle, and compared for their running time results. Results shows that ISU algorithm compared to DESS algorithm gives better/lower running time (ISU is at least twice as fast as DESS), i.e. more performance, and shows less sensitivity to model parameters. Also, ISU algorithm consumes less memory and it is simpler to implement. In the end, for further improvement of performance of ISU algorithm, delayed updating and parallelization solutions are offered. Delayed updating is a common way to optimize algorithms containing two phases of processing and updating. In order to apply delayed updating and parallelization to ISU algorithm, a solution is presented to separate sorting and updating phases of the algorithm. Then, parallelization is applied. Results show that using these techniques, can increase the performance of ISU algorithm by 20%.}, Keywords = {Rock Mechanics,Numerical analysis,Distinct Element Method,DA2 Software,Contact Detection Algorithm}, volume = {14}, Number = {3}, pages = {43-60}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی و ارتقاء عملکردی روش‌های کشف تماس برای استفاده در روش المان مجزا در مکانیک سنگ}, abstract_fa ={الگوریتم‌های کشف تماس، در شبیه‌سازی‌های المان مجزا، برای دستیابی به فهرست تماس‌های ممکن بین ذرات استفاده می‌گردند. از آنجایی که بخش مهمی از تلاش‌های محاسباتی در روش‌های المان مجزا مرتبط با کشف تماس ذرات می‌باشد، کارایی الگوریتم مورد استفاده در این روش‌ها، از اهمیت بسیاری برخوردار است. این مقاله، با هدف شناسایی مناسب‌ترین الگوریتم کشف تماس و برای پیاده‌سازی یک نرم‌افزار تحلیل عددی هیدرو مکانیکی در مسائل مکانیک سنگ به روش المان مجزا (DA2)، الگوریتم‌های موجود برای کشف تماس بلوک‌های نامدور و اندازه‌های ناهمسان را مطالعه و ارزیابی می‌نماید. برای این منظور، الگوریتم‌های کشف تماس، شامل بازرسی مستقیم (DC)، مرتب‌سازی و به‌روزآوری افزایشی (ISU) و مرتب‌سازی فضایی دو انتهایی (DESS)، در قالب نرم‌افزار DA2 پیاده‌سازی و در محیطی همسان و برای مسائل رایج در مکانیک سنگ اجرا گردیده و نتایج زمان اجرای آنها مقایسه شده‌‌است. نتایج پژوهش نشان می‌دهد که الگوریتم ISU در مقایسه با الگوریتم‌های DC و DESS، به لحاظ معیار زمان اجرا، کارایی بهتری داشته و به تغییرات پارامترهای مساله مانند تعداد بلوک‌ها، نسبت ابعادی مدل، تفرق اندازه‌ی بلوک‌ها، زوایای ناپیوستگی‌ها و زاویه‌ی اصطکاک داخلی درزه‌ها حساسیت کمتری نشان می‌دهد. در پایان، برای افزایش کارایی الگوریتم ISU، دو راه‌کار به‌روزآوری تاخیری و موازی‌سازی در به¬روزآوری، شناسایی و پیشنهاد شده‌اند. نتایج پیاده‌سازی راه‌کارها نشان داده‌است که با به‌کارگیری آن‌ها می‌توان تا ۲۰٪ سرعت الگوریتم ISU را افزایش داد.}, keywords_fa = {مکانیک سنگ,تحلیل عددی,روش المان مجزا,نرم‌افزار DA2,الگوریتم کشف تماس}, url = {http://mcej.modares.ac.ir/article-16-10641-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-10641-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Bavali, Moslem}, title = {Optimal Location of pile in Stabilization of Earth Slope}, abstract ={Stability analysis of earth slopes is among the major issues raised in geotechnical engineering which has involved so many researchers in different parts of the world. When stability of an earth slope is suspected, it is necessary to take preventive measures before instability happens. The first step to maintain the stability of an earth slope is performing excavation in the slope crest or/and filling in the slope toe. This is the cheapest way (model) for stabilization of earth slopes. If the model cannot provide the required factor of safety, it is necessary to use other stabilization methods. Numerical and laboratory methods are useful for modeling earth slopes stabilization. Modeling the stability of earth slopes using numerical methods is a common practice in geotechnical engineering. Moreover, stabilization of earth slopes using piles has been practiced by many researchers by using numerical and analytical methods. Although numerical and analytical methods have special capabilities, laboratory modeling is more reliable. Hence, it is discussed in this article. Stabilization of earth slopes with reinforced concrete piles is one of the important concerns of geotechnical engineering. Application of numerical and analytical methods to stabilization of earth slopes using piles is an issue commonly discussed by various researchers. Optimal location of concrete pile for stabilization of earth slope by means of numerical and analytical methods, has been practiced by various researchers. Their efforts have led to various results raising the question of what the optimal place for installation of a pile is. It seems that no experimental studies are conducted in this regard, which is discussed in this article. Experimental studies conducted in this article have the potential to solve the problem caused by varying and sometimes contradictory results of numerical analyses performed to find the optimal pile location. In this article, an experimental analysis of a homogeneous sand earth slope is conducted. The slope is saturated through precipitation and failure after loading by installing the reinforced concrete pile in different locations. All of the experimental tests were modeled and compared using the limit equilibrium (LE) and finite element (FE) methods, which are compliant with each other. The results obtained by experimental tests show the optimal location for installing reinforced concrete pile in a homogeneous sand slope for achieving the highest factor of safety and reduce costs of stabilization. In the present article, the optimal pile location for slope stabilization is determined by conducting laboratory studies of a layer sand slope saturated through precipitation. The resultant failure mechanism leads to acceptable results that help choose the optimal location for pile installation. The slope is stabilized by repeating the test and installing the pile in the optimal location, which is the best place to install the pile. The FE method (Plaxis software) and LE method were used to confirm the laboratory tests as well.}, Keywords = {Earth Slope,Concrete Pile,Optimal location,Stabilization}, volume = {14}, Number = {3}, pages = {61-69}, publisher = {Tarbiat Modares University}, title_fa = {بهینه یابی مکان شمع در پایدارسازی شیب های خاکی}, abstract_fa ={پایدارسازی شیب های خاکی و پیشنهاد راهکارهای گوناگون، یکی از مسائل مطرح و مهم در مهندسی ژئوتکنیک است. استفاده از روش های عددی و تحلیلی در پایدارسازیِ شیب های خاکی به کمکِ شمع، از روش های متداولی است که توسط محققین مختلف مورد بررسی قرار گرفته است. بهینه یابی مکان شمع به منظور پایدارسازی شیب های خاکی با استفاده از روش های عددی و تحلیلی توسط محققین مختلف، منجر به نتایج متعددی شده است که این سوال را در ذهن طراح مطرح می کند که بهترین مکانِ واقعی برای نصب شمع کجاست؟ به نظر می رسد که جایِ مطالعات آزمایشگاهی برای این منظور خالی است که در این مقاله به عنوان کاری جدید ارائه می شود. مطالعات آزمایشگاهیِ انجام شده در این مقاله قادر است که گرهِ ایجاد شده در نتایج مختلف و گاه متضاد تحلیل های عددی را برای یافتن مکانِ بهینه شمع باز کند. مطالعه ی آزمایشگاهی مذکور، برای شیب خاکیِ ماسه ای انجام شده است که توسط بارش مصنوعی اشباع می گردد و پس از اشباع شدن تحت بارگذاری قرار می گیرد. با قرار دادن شمع در مکان های مختلف و اشباع کردن شیب خاکی توسط بارش و بارگذاری آن ها، نتایج قابل توجه و معقولی بدست آمده است که می تواند راهگشای مناسبی برای طراحان باشد. تمام مدل های آزمایشگاهی با استفاده از روش تعادل حدی و روش اجزای محدود نیز مدل سازی و مقایسه شده اند که تطابق خوبی با یکدیگر دارند.}, keywords_fa = {شیروانی خاکی,شمع بتنی,موقعیت بهینه,پایدارسازی}, url = {http://mcej.modares.ac.ir/article-16-6796-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6796-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {hoseinzadetabrizi, hamed and vaghefi, moham}, title = {Effect of Froude Number on flow pattern and scour around T-shaped spur dikes under submerged and unsubmerged condition}, abstract ={In this research parameters influencing flow pattern and scour around submerged and nonsubmerged series of spur dikes in straight channel were investigated. Scour pattern was investigated for three angles of dikes construction, and three submergence ratio.The result showed that with increasing Froude number and decreaseing submergence ratio, scour decreases. Also because of first spur dike effect on main flow, maximum scour depth in second and third spur dike is less than first one. The location of scour and ridge height change with Froude number, submergence ratio and angle.The three dimention velocity around spur dike were analyzed Then we used flow pattern to forecast scour pattern. In this research parameters influencing flow pattern and scour around submerged and nonsubmerged series of spur dikes in straight channel were investigated. Scour pattern was investigated for three angles of dikes construction, and three submergence ratio.The result showed that with increasing Froude number and decreaseing submergence ratio, scour decreases. Also because of first spur dike effect on main flow, maximum scour depth in second and third spur dike is less than first one. The location of scour and ridge height change with Froude number, submergence ratio and angle.The three dimention velocity around spur dike were analyzed Then we used flow pattern to forecast scour pattern. In this research parameters influencing flow pattern and scour around submerged and nonsubmerged series of spur dikes in straight channel were investigated. Scour pattern was investigated for three angles of dikes construction, and three submergence ratio.The result showed that with increasing Froude number and decreaseing submergence ratio, scour decreases. Also because of first spur dike effect on main flow, maximum scour depth in second and third spur dike is less than first one. The location of scour and ridge height change with Froude number, submergence ratio and angle.The three dimention velocity around spur dike were analyzed Then we used flow pattern to forecast scour pattern. In this research parameters influencing flow pattern and scour around submerged and nonsubmerged series of spur dikes in straight channel were investigated. Scour pattern was investigated for three angles of dikes construction, and three submergence ratio.The result showed that with increasing Froude number and decreaseing submergence ratio, scour decreases. Also because of first spur dike effect on main flow, maximum scour depth in second and third spur dike is less than first one. The location of scour and ridge height change with Froude number, submergence ratio and angle.The three dimention velocity around spur dike were analyzed Then we used flow pattern to forecast scour pattern. In this research parameters influencing flow pattern and scour around submerged and nonsubmerged series of spur dikes in straight channel were investigated. Scour pattern was investigated for three angles of dikes construction, and three submergence ratio.The result showed that with increasing Froude}, Keywords = {spur,T shape spur dikes,Froude number,submergence ratio,Flow pattern}, volume = {14}, Number = {3}, pages = {71-82}, publisher = {Tarbiat Modares University}, title_fa = {تاثیر عدد فرود جریان بر الگوی جریان و آبشستگی اطراف آبشکن‌های سری در مسیر مستقیم در حالت مستغرق و غیرمستغرق}, abstract_fa ={در این تحقیق به مطالعه آزمایشگاهی الگوی جریان و آبشستگی پیرامون آبشکن¬¬های سرسپری سری مستغرق و غیرمستغرق در مسیر مستقیم پرداخته ¬می¬شود. بررسی الگوی آبشستگی در سه زاویه مختلف قرارگیری آبشکن نسبت به ساحل مجاور، در درصد استغراق¬های مختلف و سه عدد فرود جریان نشان¬دهنده افزایش عمق ماکزیمم آبشستگی در لبه بالا دست آبشکن¬ها با افزایش عدد فرود و کاهش درصد استغراق است. همچنین به¬دلیل تاثیر آبشکن¬های سری، عمق ماکزیمم آبشستگی در آبشکن سوم کمتر از آبشکن دوم، و آبشکن دوم کمتر از آبشکن اول است. با کاهش عدد فرود و افزایش درصد استغراق آبشکن¬ها، تاثیر آبشکن¬های سری کمتر شده و آبشکن¬ها تقریبا به صورت مجزا عمل می¬نمایند. محل شروع رسوب¬گذاری و مقدار آن با تغییر عدد فرود جریان، درصد استغراق آّبشکن¬ها و زاویه قرارگیری آن نسبت به ساحل مجاور تغییر می¬کند که در این تحقیق به بررسی و مقایسه این تغییرات پرداخته می¬شود. آزمایش الگوی جریان اطراف آبشکن جاذب، در شرایط آستانه حرکت و در درصد استغراق 50 درصد انجام شد که با بررسی جهت و مقدار سرعت جریان سه¬بعدی و تنش برشی بستر در جلوی بال آبشکن¬ها و محدوده¬ی بین آبشکن¬ها پیش¬بینی قابل قبولی از آبشستگی در پیرامون آبشکن¬های سرسپری بدست می¬آید.}, keywords_fa = {آبشستگی,آبشکن‌های سرسپری سری,عدد فرود,درصد استغراق,الگوی جریان}, url = {http://mcej.modares.ac.ir/article-16-10811-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-10811-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {SadatLavasaniBozorg, Seyed Mohammad Ali and Ziari, Hasan and Divandari, Hasan and Izadi, Amir}, title = {In situ evaluation of modern methods for pavement layers density determination}, abstract ={Density is the best criterion in pavements quality control. Determination of asphalt mixture density while compaction and after that is an important issue from two aspects of compaction level measurement and the time of compaction process termination. The most common and accurate method of in situ density determination is core making. Common procedure is to use a core gear and performing density test on cores in laboratory. Being expensive, time consuming and unrepeatable test, besides causing pavement deterioration are disadvantages of core making. Time consuming causes layer weakness doesn’t discover soon enough to do some modifications on that. Nondestructive density tests became very popular in recent years. These tests don’t cause any deterioration on pavement surface and are more reach than core making and repeatable since are NDT which are divided to nuclear and non nuclear NDT tests. PQI 301 electromagnetic and Troxler (HS-5001EZ) nuclear devices field evaluation were done in this research. After statistical analysis it was resulted that PQI is convenience for asphalt layers and nuclear is convenience for granular layers.}, Keywords = {Density determination,Core making,Nuclear and Non Nuclear NDT methods}, volume = {14}, Number = {3}, pages = {83-92}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی میدانی روش های نوین تعیین دانسیته لایه های روسازی}, abstract_fa ={چگالی بهترین معیار سنجش و کنترل کیفیت روسازی اجرا شده می باشد. تعیین چگالی مخلوط آسفالتی در حین عملیات تراکم و پس از آن، از دو جهت تعیین میزان تراکم و زمان اتمام عملیات دارای اهمیت می باشد. در حال حاضر متداول ترین و البته دقیق ترین روش‌ تعیین دانسیته در محل مخلوط آسفالتی، روش مغزه گیری می باشد. روش معمول برای انجام این کار استفاده از مغزه گیر و انجام آزمایش تعیین چگالی بر روی مغزه های بدست آمده در آزمایشگاه می باشد. اما این روش دارای معایبی شامل ایجاد خرابی در سطح روسازی، هزینه نسبتاً بالا، عدم تکرارپذیری و پایش دانسیته برای یک نقطه خاص و صرف زمان زیاد می باشد. زمان بر بودن انجام این آزمایش، منجر می‌شود که نقاط ضعف لایه ناشی از عدم تراکم لازم به سرعت مشخص نشوند و لذا اقدامات اصلاحی در زمان مناسب صورت نگیرند. در سال های اخیر استفاده از آزمایش های غیر مخرب تعیین دانسیته، با استقبال زیادی مواجه شده است. این نوع آزمایش ها در سطح روسازی ایجاد خرابی نمی کنند، هزینه انجام آنها کمتر از مغزه گیری می باشد و بعلت عدم ایجاد خرابی بوسیله آنها تکرارپذیرند، که شامل دو روش غیرمخرب هسته ای و غیرهسته ای می باشند. در این تحقیق ارزیابی میدانی دستگاه الکترومغناطیسیPQI مدل 301 و دستگاه هسته ای Troxler مدلHS-5001EZ انجام گردید که بعد از انجام تحلیل های آماری مشخص شد که دستگاهPQI مناسب برای تعیین دانسیته لایه های آسفالتی و دستگاه هسته ای برای تعیین دانسیته لایه های سنگدانه ای مناسب می باشند.}, keywords_fa = {تعیین دانسیته,مغزه گیری,روش های غیرمخرب هسته ای و غیر هسته ای}, url = {http://mcej.modares.ac.ir/article-16-7632-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7632-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {SoltaniMohammadi, Masoud and sepasi, mo}, title = {Modeling and Studying the Seismic Performance of Adjacent Reinforced Concrete Frames with Applying the Effect of Pounding}, abstract ={It is well known that the interaction between adjacent buildings with limited separation distance or in the other ‎words earthquake-induced structural pounding has considerable effect on seismic performance of buildings. Earthquake induced vibrations may cause impact between two adjacent buildings with inadequate separation distance. Pounding hazard is considerable particularly in populated residential regions because of the limited separation distance due to limitation of lands. This ‎phenomenon may result in substantial damage or even contributes to total structural collapse of structures. Major seismic events during the past decade such as those that have occurred in Northridge, Imperial Valley (May 18,1940), California (1994), Kobe, Japan (1995), Turkey (1999), Taiwan (1999) and Bhuj, Central Western India (2001) have continued to demonstrate the destructive power of earthquakes, with destruction of engineered buildings, bridges, industrial and port facilities as well as giving rise to great economic losses. Among the possible structural damages, seismic induced pounding has been commonly observed in several earthquakes. As the cost of land in cities increases, the need to build multistory buildings in close proximity to each other also increases. Sometimes, construction materials, other objects and any projections from a building may also decrease the spacing provided between the buildings. This leads to the problem of pounding of these closely placed buildings when responding to earthquake ground motion. The main purpose of this paper is the modeling of adjacent structures in order to study the effects of pounding. Among the existing models, nonlinear visco-elastic model has been selected for numerical simulation of pounding. To study the effect of pounding on seismic performance of reinforced concrete structures, two RC frames with 4 and 6 stories are selected and their seismic performance under pounding effects are numerically studied. The effect of storey and total height of structures, size of separation distance and mass of buildings in series on the impact has been investigated in adjacent RC frames. The selected frames have been designed according to direct displacement based design method in order to investigate the effect of impact on ductility demand and obtain a desired maximum induced displacement at a considered hazard level. Then by putting the structural models with different dynamic characteristics close together, the effect of altitude, size of gap, and story height on performance of two adjacent structures has been studied. The nonlinear time history analysis and incremental dynamic analysis (IDA) has been done to predict the seismic collapse capacity of systems. The results of analysis show that the effect of pounding severely depends on the phase difference of vibrations of adjacent structures. The phase difference itself, depends on mass, stiffness and seismic capacity of adjacent systems and the value of imposed plastic deformation as well. The effect of pounding in structural systems with the same height with little difference in initial periods is negligible, whereas the local effect of pounding especially in the case of floor to column impact is considerable.}, Keywords = {structural pounding,reinforced concrete frames,Seismic Performance,direct displacement-based design}, volume = {14}, Number = {3}, pages = {93-106}, publisher = {Tarbiat Modares University}, title_fa = {مدلسازی و بررسی رفتار لرزه ای قابهای بتن مسلح مجاور هم با اعمال اثرات برخورد}, abstract_fa ={در هنگام زلزله، ارتعاش غیرهم فاز ساختمانهای مجاور باعث برخورد و ضربه بین آنها می شود که شرایط بارگذاری بحرانی‌تری از حالت ارتعاش بدون ضربه ایجاد می‌کند. فراوانی نمونه‌هایی از عدم اجرای درز انقطاع در ساختمانهای موجود، اهمیت پرداختن به این موضوع را افزایش می‌دهد. در تحقیق حاضر پس از توسعه و پیاده سازی مدل ویسکو الاستیک غیر خطی برای شبیه سازی برخورد سازه ها در نرم افزار مورد استفاده، با مدلسازی قابهای بتن مسلح مجاور هم در شرایط مختلف و بررسی رفتار آنها تحت اثر مجموعه ای از رکوردهای واقعی زلزله و تحت شتاب افزاینده، اثر برخورد سازه¬ها مورد مطالعه قرار می گیرد. این قابها نخست به روش مستقیم طراحی بر اساس تغییرمکان برای اطمینان به دستیابی به یک تغییرمکان از پیش مشخص در سطح خطر مورد نظر، طراحی شده سپس با قرار دادن مدلهای سازه‌ای با ارتفاع متفاوت در کنار یکدیگر و فاصله درز انقطاع مختلف، تحت مجموعه رکوردهای نمونه انتخابی مورد تحلیل دینامیکی افزاینده قرار گرفته و اثر برخورد سازه‌ها بر تغییرمکان نسبی طبقات و ظرفیت فروریزش مورد بررسی قرار می گیرد. نتایج بدست آمده گویای این مطلب است که با در نظر گرفتن شکست برشی سازه‌های مجاور هم با تراز طبقات متفاوت، ظرفیت فروریزش سازه‌های مجاور پس از برخورد به شدت کاهش می‌یابد. بنابراین اثرات موضعی برخورد در محل ضربه اهمیت بالایی دارد و لازم است در ارزیابی لرزه‌ای سازه‌ها مورد بررسی دقیق قرار گیرد.}, keywords_fa = {برخورد سازه ها,قابهای بتن مسلح,عملکرد لرزه‌ای,طراحی بر اساس تغییرمکان}, url = {http://mcej.modares.ac.ir/article-16-6201-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6201-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Ghoddousi, Parviz}, title = {Evaluation of yield stress and plastic viscosity of self-consolidating concrete mixtures containing stone powder using new concrete rheometer made for the first time in Iran}, abstract ={Self-consolidating concrete(SCC) application is using in the construction projects more and more because of its advantages include high quality and flow under its own weight without any vibration. The rheological properties of SCC are very important that it has a significant effect on mechanical properties and durability. In this study, using a special concrete rheometer that has made for the first time in Iran, rheological parameters of SCC are determined. For performance evaluation and calibration of device, standard oil with determined viscosity by factory is used. Plastic viscosity value obtained by rheometer was equal 2.208 Pa.S and the oil viscosity provided by the factory was 2.219. Therefore results show that Rheometer performance is according with design plan and rheological parameters can be determined well by this device. Also some experimental SCC mixture contains two kinds of powder as filler is made. The calculated values of plastic viscosity and yield stress of these mixtures show that SCC containing limestone powder to 200 kg/m3 indicating the best performance and with increasing the amount of filler to 300 kg/m3 cause to increase yield stress. Self-consolidating concrete(SCC) application is using in the construction projects more and more because of its advantages include high quality and flow under its own weight without any vibration. The rheological properties of SCC are very important that it has a significant effect on mechanical properties and durability. In this study, using a special concrete rheometer that has made for the first time in Iran, rheological parameters of SCC are determined. For performance evaluation and calibration of device, standard oil with determined viscosity by factory is used. Plastic viscosity value obtained by rheometer was equal 2.208 Pa.S and the oil viscosity provided by the factory was 2.219. Therefore results show that Rheometer performance is according with design plan and rheological parameters can be determined well by this device. Also some experimental SCC mixture contains two kinds of powder as filler is made. The calculated values of plastic viscosity and yield stress of these mixtures show that SCC containing limestone powder to 200 kg/m3 indicating the best performance and with increasing the amount of filler to 300 kg/m3 cause to increase yield stress. Self-consolidating concrete(SCC) application is using in the construction projects more and more because of its advantages include high quality and flow under its own weight without any vibration. The rheological properties of SCC are very important that it has a significant effect on mechanical properties and durability. In this study, using a special concrete rheometer that has made for the first time in Iran, rheological parameters of SCC are determined. For performance evaluation and calibration of device, standard oil with determined viscosity by factory is used. Plastic viscosity value obtained by rheometer was equal 2.208 Pa.S and the oil viscosity provided by the factory was 2.219}, Keywords = {Concrete rheometer,Yield stress,Plastic viscosity,Self-consolidating concrete,Bingham model}, volume = {14}, Number = {3}, pages = {107-115}, publisher = {Tarbiat Modares University}, title_fa = {بررسی تنش جاری شدن و ویسکوزیته پلاستیک مخلوط های بتن خود تراکم حاوی پودر سنگ با استفاده از دستگاه رئومتر بتن ساخته شده برای اولین بار در ایران}, abstract_fa ={استفاده از بتن خود تراکم در پروژه های عمرانی بدلیل مزایای آن شامل کیفیت بالا و جاری شدن تحت وزن خود بدون نیاز به لرزش ، در حال افزایش است. رئولوژی این بتن یکی از خواص بسیار مهم آن است که بر روی خصوصیات مکانیکی و دوام آن تاثیر چشمگیری دارد. در این تحقیق با استفاده از دستگاه رئومتر ویژه بتن که برای اولین بار در ایران ساخته شده ، پارامتر های رئولوژی بتن خود تراکم تعیین شده است. برای اعتبار سنجی عملکرد دستگاه و کالیبراسیون آن از روغن با ویسکوزیته مشخص استفاده شده است. مقدار ویسکوزیته پلاستیک بدست آمده توسط دستگاه برابر 208/2 پاسکال ثانیه و مقدار ارائه شده ویسکوزیته روغن توسط کارخانه برابر 219/2 شده است. بنابراین نتایج نشان می دهد که دستگاه رئومتر ساخته شده بخوبی منطبق با طرح بوده و پارامتر های رئولوژی توسط دستگاه با دقت مناسبی قابل تعیین است. همچنین چند مخلوط آزمایشی بتن خود تراکم حاوی دو نوع پودر سنگ به عنوان پر کننده ساخته شده است. مقادیر محاسبه شده ویسکوزیته پلاستیک و تنش تسلیم این مخلوط ها نشان می دهد نمونه حاوی پودرسنگ آهک تا 200 کیلوگرم در متر مکعب بهترین عملکرد را نشان می دهد و با افزایش این مقدار به 300 کیلوگرم در متر مکعب مقدار تنش جاری شدن بتن افزایش می یابد.}, keywords_fa = {رئومتر بتن,تنش جاری شدن,ویسکوزیته پلاستیک,بتن خود تراکم,مدل بینگام}, url = {http://mcej.modares.ac.ir/article-16-1205-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1205-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Alaedini, Shohreh and KABIR, MOHAMMADZAMAN and Hejabi, Hadi}, title = {Performance of fiber reinforced polymers (FRPs) retrofitting used in RC frames}, abstract ={In the recent years, attempts have been made to prove effectiveness of FRPs in retrofitting/repairing of the reinforced concrete (RC) components. The use of fiber-reinforced polymers (FRP) to create composite concrete structures has increased in recent years. However, the seismic performance of RC structures retrofitted using FRP composites is yet to be scrutinized in terms of improving strength, ductility. This is of high importance if the retrofitted structures are to withstand higher seismic ground motions. The purpose of this study was to investigate the seismic performance of RC joint in frame structures under cyclic lateral loading. Analytical calculations using a finite element method (FEM) are presented for the strength, crack pattern; behavior of frames strengthened with layers of FRP and an experimental study of firth and third author of this paper is carried out to verify the mechanical properties of the proposed. The specimens were tested in a 3D test frame in structure laboratory of civil and environmental engineering department in AmirKabir University of Technology. Analytical models were investigated in LS-DYNA environment. Three test specimens were constructed and tested under cyclic lateral loading. Three-dimensional nonlinear finite element models for the RC frames were developed and simulated with the LS-DYNA finite element analysis (FEA) software. Three 1/3 scaled one-bay and one-storey. Frame designed was carried out based on ACI318 code. These specimens were typical as-built frames abstracted from the existing middle-rise residential buildings in Iran. Two specimens were reinforced by CFRP at the ends of beams, columns and at the joints; one specimen the other specimen was not reinforced and was used for comparison. The retrofitted specimens were built with different ways of wrapping FRP sheets at the frame’s joints and both ends of beams and columns. The wraps were provided to prevent the peeling of the laminates this was aimed to investigate the effective ways of strengthening and repairing of the frame by applying different directions of CFRP and GFRP fibers. The analytical models are used to assess the efficiency of the FRP composites rehabilitation by comparison between intact and retrofitted specimens. Specimens were reinforced by FRP at the ends of beams, columns and at the joints; one specimen was not reinforced and was used for comparison. Also, the effect of laminate architecture, arrangement and type of material was considered. For achieving this purpose eleven models were analyzed in finite element model. The Finite element analysis results indicated that the choice of the Fiber composite materials, the laminate and wraps arrangement and thickness affected the enhancement of the structural joint performance significantly. The results provide an important insight of the role of FRP sheets in improving the earthquake resistance of frame buildings. . Keywords: reinforced concrete; frame; FRP retrofit; Analytical; cyclic loading.}, Keywords = {FRP,. Keywords: reinforced concrete,Frame,FRP retrofit,analytical,Cyclic loading}, volume = {14}, Number = {3}, pages = {117-127}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی عملکرد قاب بتنی تقویت شده توسط پوشش‌های پلیمری FRP تحت بار سیکلی}, abstract_fa ={در سال¬های اخیر تحقیقات فراوانی در استفاده از کامپوزیت¬های FRP در زمینه مقاوم¬سازی و بهسازی سازه¬های بتنی انجام شده است. با این وجود بیشتر تحقیقات بر روی اعضای منفرد همانند تیر، ستون، اتصال تیر-ستون انجام شده است. لذا، تحقیق در زمینه بررسی رفتار کلی یک قاب بتنی تقویت شده توسط الیاف پلیمری در برابر بار¬های سیکلی محدود می¬باشد. قاب¬های بتن آرمه چهارچوب اصلی و باربر سازه¬های بتن آرمه را تشکیل می¬دهند، مقاوم کردن و بهسازی آنها نقش مهمی در مقاوم¬سازی کل سازه ایفا می¬کند. هدف اصلی در این مقاله، بررسی اثرات بهسازی با پوشش FRP در پاسخ قاب تحت بارهای سیکلی جانبی با استفاده از نرم افزار المان محدود LS-DYNA می¬باشد. صحت سنجی نتایج این تحقیق با نتایج تجربی ترمیم قاب¬های بتن آرمه که در سال 2012 و در آزمایشگاه دانشگاه صنعتی امیرکبیر توسط نویسندگان اول و سوم انجام شده است، صورت گرفته است. همچنین، نمونه¬ها در سه دسته کلی نمونه¬های شاهد ، نمونه¬تقویت شده و نمونه¬هایی برای بررسی عوامل موثر در بهبود رفتار قاب تقویت شده، تحت بارگذاری قرار می¬گیرند. اثر پارامتر¬های مختلف موثر در رفتار قاب بهسازی شده همانند جنس الیاف (کربن یا شیشه)، آرایش تقویت FRP به صورت کمی و کیفی نیز مورد آنالیز قرار گرفته¬اند. نتایج تحقیقات نشان¬دهنده نقش قابل توجه FRP در افزایش مقاومت، سختی و استهلاک انرژی در قاب¬های بهسازی شده می¬باشد. کلمات کلیدی : قاب بتنی، بارگذاری سیکلی، مقاوم¬سازی، FRP، المان محدود}, keywords_fa = {کلمات کلیدی : قاب بتنی,بارگذاری سیکلی,مقاوم‌سازی,المان محدود}, url = {http://mcej.modares.ac.ir/article-16-6535-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6535-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Kouchakzadeh, Mohammad and nasiri, FARZIN}, title = {Evaluation of the efficiency of using surface water simulation results to improve the accuracy of groundwater simulation in Silakhor shallow aquifer located in Lorestan province (Iran)}, abstract ={This paper evaluates the efficiency of using surface water simulation results to improve the accuracy of groundwater simulation due to improving the accuracy of its input boundary conditions. The three most important data sets of boundary conditions in groundwater flow simulation are groundwater recharge, evapotranspiration rates and their regional distributions that little information is usually available about them. Moreover, the incorrect definition of these values can lead to uncertain groundwater modeling that is not applicable for groundwater resources management. In the most of previous studies done in Iran, percentage of the average regional precipitation and the local pan evaporation data (available from local weather stations) are used as the regional groundwater recharge and evapotranspiration rates, respectively but they have high uncertainty in their quantities and spatial distributions. In this research in order to solve this problem, the values of groundwater recharge and evapotranspiration rates and their regional distributions, obtained from SWAT modeling results, were used as the related input boundary conditions data in groundwater flow simulation using MODFLOW model. SWAT model is a comprehensive watershed model that calculates these values in each Hydrologic Response Unit (HRU). The study aquifer in this research was Silakhor shallow aquifer with the area of 590 km2 located in Lorestan province of Iran. The annual water table depth in different locations of this aquifer had been reported from 0.75 to 40 meter. Using this approach for improving boundary conditions in groundwater simulation and its evaluation was carried out for first time in Iran. The SWAT model was run for a period of 7 years from 2002 to 2008. After calibration and verification of the model using hydrodynamic data of Silakhor and Tire-Doroud gauging stations, the values of groundwater recharge and evapotranspiration rates in each HRU were extracted. The MODFLOW model was run for the period of 9 months of 2009 using these simulated boundary conditions and the other required information. For comparison of the calculated values with the observed values of water table depths in the 20 piezometers for the period of 9 months of 2009, the Root Mean Square Error (RMSE) and Mean Absolute Errors (MAE) were obtained 1m and less than 1m, respectively. In continuous of this research, the values of 5, 10 and 15 percent of regional average precipitation and the evaporation data in Silakhor pan evaporation gauging station were used as usual boundary condition for groundwater simulation using the MODFLOW model. For comparison of the simulated values of water tables depths obtained from this usual approach with the observed ones, the both of RMSE and MAE values were calculated more than 1 meter. Therefore this research showed that using integrated SWAT-MODFLOW models was more applicable in the groundwater simulation in the study aquifer.}, Keywords = {SWAT model,MODFLOW model,Boundary condition,Silakhor plain aquifer}, volume = {14}, Number = {3}, pages = {129-138}, publisher = {Tarbiat Modares University}, title_fa = {بررسی کارایی استفاده از نتایج شبیه سازی آب سطحی در افزایش دقت شبیه سازی جریان آب زیرزمینی در آبخوان کم عمق دشت سیلاخور در استان لرستان}, abstract_fa ={در این مقاله، کارایی استفاده از نتایج شبیه سازی جریان آب سطحی در افزایش دقت شبیه سازی جریان آب زیرزمینی بررسی شده است. از مهمترین ورودی های شرایط مرزی در شبیه سازی جریان آب زیرزمینی مقادیر تغذیه، تبخیر و تعرق و نحوه توزیع آنها در منطقه می باشد که همواره اطلاعات کمی از آنها در دسترس است. تعریف نادرست از این مقادیر در شبیه سازی آبخوان منجر به کاهش دقت و عدم کارایی مدل در مدیریت منابع آب زیرزمینی می گردد. برای حل این مشکل، از نتایج شبیه سازی جریان آب سطحی با مدل SWAT برای مقادیر تغذیه و تبخیر و تعرق به عنوان ورودیهای مدل MODFLOW استفاده گردید. در نتیجه، این مقادیر با قطعیت بالاتر و توزیع مناسبتری برای این مدل تعریف شدند. کارایی این روش در آبخوان کم عمق دشت سیلاخور در ایران مورد ارزیابی قرار گرفت. با مقایسه تراز ایستایی شبیه سازی شده و مشاهده شده در 20 چاه پیزومتریک در دوره 9 ماهه از سال 2009، میانگین خطای مطلق کمتر از 1 متر و مجذور میانگین خطاها 1 متر به دست آمد. بار دیگر آبخوان دشت سیلاخور با استفاده از مدل MODFLOW و لحاظ نمودن درصدی از بارش منطقه به عنوان تغذیه و اطلاعات موجود در ایستگاه تبخیرسنجی سیلاخور برای تبخیر و تعرق و بدون استفاده از نتایج مدل SWAT شبیه سازی گردید. مقایسه دقت به دست آمده از روش مدل ترکیبی با روش دوم، نشان از کارایی روش ترکیبی در افزایش دقت دارد.}, keywords_fa = {مدل SWAT,مدل MODFLOW,شرایط مرزی,آبخوان دشت سیلاخور}, url = {http://mcej.modares.ac.ir/article-16-865-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-865-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Massumi, Ali}, title = {Redundancy in RC Moment Resisting Frames II: Evaluating the Effects of Redundancy on Seismic Behavior}, abstract ={Structural redundancy is a non-independent concept in structural engineering and has inherent dependence on structural parameters such as overstrength and ductility, so that both of overstrength and ductility capacities should change corresponding to any variation in structural redundancy. Nevertheless, most of researchers notified that taking any increase in structural redundancy should be a desirable property to deal with more effectively against earthquake loading. Furthermore, this issue can reduce structural sensitivity to abnormal loads. In this research to clarify the pure role of redundancy in earthquake resistant design and to distinguish the role of redundancy from total overstrength capacity, a number of 3D reinforced concrete special moment resistant frames (RC-SMRF) with equal ultimate base shear coefficient were designed. The dynamic behavior parameters of the designed structures under natural strong ground motion were evaluated, especially with regards to configuration of nonlinear deformations. The analytical outputs obtained from analyzed structures are illustrated ensembles of maximum acceleration, maximum velocity and maximum drift of each story. Furthermore, adequacy and accuracy of response modification factor which should be assigned as general indicator of quality of total seismic behavior has been studied conceptually. The results of this research indicate that: (i) Assigning an increase in structural redundancy would not always lead to efficient improvement in structural seismic behavior. Furthermore, notification to process of increased redundancy should not be consider as a criterion for any basic improvement in structural performance. This issue means that it is better to consider the effects of redundancy on important seismic parameters such as both the structural member ductility and the overstrength capacity. (ii) The calculated response modification factors as mentioned in this research, can consider as an index of quality of structural dynamic performance which is corresponding to a certain level of redundancy. Accordingly, the above statement should be notified in general cases of those earthquake loadings which would cause a certain level of story drift. This certain level of story drift would denote the structural behavior typically follows the calculated response modification factor. Oppositely, if an earthquake loading causes more story drift from that assigned certain level, structural behavior typically does not follow the calculated response modification factor. (iii) The codified procedure of calculation of response modification factor which were discussed and assessed in this study, cannot be realized subjected to those input strong ground motions that able to display high amplitude and long period pulse or pulses in their velocity time history. It is important to know that strong near-fault ground motions often have an impulsive feature and impose large amounts of sudden intense kinematic energy which must be dissipated by structural system during a short period of time. This issue causes amplified deformation demands in structures which are associated with very few cycles of cumulative plastic deformations. Hence, the earthquake damages due to these seismic load cases are effectively related to maximum deformation as well as maximum ductility. Yet, structures cannot accomplish based on the calculated response modification factor in the mentioned cases.}, Keywords = {Redundancy,ductility,Seismic behavior,Nonlinear Incremental Dynamic Analysis}, volume = {14}, Number = {3}, pages = {139-152}, publisher = {Tarbiat Modares University}, title_fa = {تأثیرات نامعینی بر رفتار لرزه‌ای قاب‌های خمشی بتن مسلح}, abstract_fa ={نامعینی سازه‌ها یک مفهوم نامستقل در مهندسی سازه است که وابستگی ذاتی به عواملی چون مقاومت افزون و شکل‌پذیری سازه‌ها دارد؛ با این وجود عموم پژوهشگران افزایش نامعینی را خاصیتی مطلوب در سازه‌ها برای مقابله موثرتر در برابر بارهای تصادفی نظیر بارهای زلزله دانسته‌اند. در این پژوهش به منظور تفکیک نقش نامعینی از مقاومت‌افزون، تعدادی سازه بتن مسلح با سیستم قاب خمشی که مقاومت نهایی یکسان دارند طرح شده است. رفتار لرزه‌ای این سازه‌ها، از نقطه نظر پارامترهای پاسخ دینامیکی سازه‌ها، تحت شتاب‌نگاشت‌های طبیعی زلزله مورد ارزیابی قرار گرفته است. همچنین کفایت ضرایب رفتار به‌دست آمده در این تحقیق، به عنوان شاخصی از کیفیت رفتار سازه‌ها در زلزله، مورد بررسی قرار گرفته است. نتایج حاصل بیانگر این است که: الف) افزایش نامعینی به تنهایی نمی‌تواند معیاری برای بهبود رفتار سازه‌ها تلقی شود و باید تاثیرات نامعینی بر سایر پارامترهای موثر بر رفتار سازه‌ها لحاظ شود. ب) ضرایب رفتار به‌دست آمده در این تحقیق می‌تواند به عنوان شاخصی از کیفیت رفتار سازه‌ها، برای بارگذاری‌هایی که در سازه تغییر مکان نسبی به میزان مشخصی ایجاد می‌کنند، باشد؛ اما برای بارگذاری‌هایی که تغییر مکان نسبی بیش از آن حد مشخص ایجاد می‌کنند، رفتار سازه‌ها به طور معمول از ضریب رفتار تبعیت نمی‌کند.}, keywords_fa = {نامعینی,شکل پذیری,رفتار لرزه‌ای,تحلیل دینامیکی غیرخطی با شتاب فزاینده}, url = {http://mcej.modares.ac.ir/article-16-11887-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11887-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Hakimpour, Seyed Mehrab and Esmaeili, Mortez}, title = {Numerical Modeling effectiveness of Stone Column in Mitigation of Liquefaction During Earthquak}, abstract ={During recent earthquakes, it was observed that liquefaction can cause severe damages to several countries' infrastructures including the buildings, bridges, road and railways in the form of significant settlement and the relevant shear failures of subgrade soil. Amongst the various rehabilitation methods of the soils tending to be liquefied, utilization of the stone column have encountered with more attention because of its beneficial characteristics from both technical and economical points of view. One of the major issues in this matter is their efficiency in liquefaction mitigation in the single and group forms. For this purpose the current study has dedicated to numerical investigation of the problem of stone column efficiency in dissipating the excess pore water pressure during the earthquake excitation, and The reliability of the numerical modeling is verified via a centrifuge test results of VELACS project. a three dimensional analysis is carried out using FLAC3D. Also, effects of various parameters such as stone column diameter, stone columns distances on the liquefaction resistance of NEVADA sand soil are investigated.}, Keywords = {Liquefaction,Pore water pressure,Improvement,stone columns,Radial drainage}, volume = {14}, Number = {3}, pages = {153-204}, publisher = {Tarbiat Modares University}, title_fa = {تحلیل عددی تاثیر ستون سنگی برای کاهش خطر روانگرایی خاک در حین زلزله}, abstract_fa ={یکی از عوامل خرابی سازه هایی که بر روی بستر های ریز دانه سیلتی و ماسه ای اشباع، قرار گرفته اند وقوع پدیده روانگرائی و ایجاد نشست و گسیختگی ناشی از آن است. با توجه به طبیعت سه بعدی حاکم بر اندرکنش ستون سنگی با محیط پیرامونی، به شکل تکی و گروهی در شرایط زلزله، بررسی میزان تاثیر گذاری این روش بر کاهش اثرات روانگرایی در توده های ماسه ای اشباع، موضوع تحقیق حاضر در نظر گرفته شده است. برای این منظور در گام نخست وقوع روانگرایی به روش عددی تفاضل محدود و به کمک نرم افزار FLAC3D مورد بررسی قرار گرفته و نتایج حاصل از این تحلیل با نتایج آزمایش شماره یک پروژه بین المللی VELACS مقایسه و بدین وسیله اعتبار سنجی حل عددی نرم افزار با دقت مناسبی صورت پذیرفته است. در ادامه برای نشان دادن تاثیر ستون سنگی تکی با قطرهای مختلف بر کاهش روانگرائی، مدلسازی مربوطه انجام و نتایج در قالب کاهش اضافه فشار حفره ای در سطح و عمق مورد نظر ارزیابی شده است. در پایان نیز با بکار گیری چیدمان مربعی برای ستون های سنگی دامنه کارائی این ستون ها به فرم گروهی با بررسی همزمان اثر قطر و فاصله مورد بررسی قرار گرفته است. نتایج بدست آمده بیانگر تاثیر ستون سنگی در زهکشی شعاعی و کاهش فشار آب حفره ای در منطقه ای به اندازه 2 تا 5/2 برابر قطر ستون سنگی در خاک اطراف آن می باشد.}, keywords_fa = {روانگرایی,فشار آب حفره ای,بهسازی,ستون های سنگی,زهکشی شعاعی}, url = {http://mcej.modares.ac.ir/article-16-11321-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11321-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {bahramiyarahmadi, mohamm}, title = {Bed topography variations in a 90° mild bend due to wedge-shaped spur dike}, abstract ={To control the outer bend of river from scour different structures such as spur dike, bendway weir and submerged vane can be used for modification of flow pattern. With interaction of these structures and water flow scour around structure occurs that is the main cause of their failures. It is assumed that the change of geometry and layout of structure can change bed topography for its stability and that is the purpose of the present study. Therefore, in this study a Triangle-shaped spur dike with different angles (23, 30, 40, 60 and 70 degrees) to the upstream direction under different hydraulic conditions (Froude numbers 0.194, 0.214, 0.233 and 0.253) was tested. For all experiments, single Triangle-shaped spur dike was installed outside bend of flume in 72° position which maximum scour depth is usually occurring. For all experiments, flow depth was kept constant equal to 13 cm. At the end of each experiment bed topography was measured and from that the scouring zone, maximum scour depth and distance of scour hole was computed. The results showed that the overall scour hole is created in toe of the spur dike that is expanded to the upstream and downstream structure. Triangle-shaped spur dike with 23 and 60 degree installation was found to create the minimum and maximum scour depth as well as its distance from the outer bank respectively. The maximum scour depth for spur dike with angles of 23 and 60° was measured to be 0.127 and 0.496 of the spur dike effective length respectively. In addition, the maximum scour depth distance of above mentioned angles from the outer bank was respectively, 0.743 and 1.6 the effective length of structure. Eroded sediments were deposited downstream the spur dike and point bars are developed. By increasing of spur dike angle, the point bars are formed away from the outer bank and extended in flume width. For spur dike angles of 23 and 70° the point bar distance from the outer bank was equal to 0.228 and 0.365 effective length of the structure respectively. To control the outer bend of river from scour different structures such as spur dike, bendway weir and submerged vane can be used for modification of flow pattern. With interaction of these structures and water flow scour around structure occurs that is the main cause of their failures. It is assumed that the change of geometry and layout of structure can change bed topography for its stability and that is the purpose of the present study. Therefore, in this study a Triangle-shaped spur dike with different angles (23, 30, 40, 60 and 70 degrees) to the upstream direction under different hydraulic conditions (Froude numbers 0.194, 0.214, 0.233 and 0.253) was tested. For all experiments, single Triangle-shaped spur dike was installed outside bend of flume in 72° position which maximum scour depth is usually occurring. For all experiments, flow depth was kept constant equal to 13 cm.}, Keywords = {Triangle-shaped spur dike,90° mild bend,scour and deposition}, volume = {14}, Number = {3}, pages = {165-175}, publisher = {Tarbiat Modares University}, title_fa = {تغییرات توپوگرافی بستر در قوس ملایم 90 درجه با نصب آبشکن مثلثی‌ شکل}, abstract_fa ={به منظور کنترل آبشستگی در قوس بیرونی رودخانه ¬ها از سازه ¬های مختلفی مانند آبشکن، سرریز مستغرق، صفحات مستغرق و غیره جهت اصلاح الگوی جریان رودخانه استفاده می ‌شود. از اندرکنش این سازه‌ ها و جریان آب، در اطراف سازه آبشستگی بوجود می ¬آید که عامل اصلی تخریب آنها می ‌باشد. فرض بر اینست که تغییر هندسه و جانمائی سازه می ‌تواند توپوگرافی بستر را در جهت پایداری آن تغییر دهد و این از اهداف تحقیق حاضر است. لذا در این تحقیق صفحه گوه ‌ای شکل با زوایای مختلف نصب (23، 30، 40، 60 و 70 درجه) درجهت بالادست و تحت شرایط هیدرولیکی متفاوت مورد آزمایش قرار گرفت. در همه آزمایشات تک صفحه گوه ¬ای شکل در موقعیت زاویه 72 درجه نصب گردید. نتایج این تحقیق نشان دادند که زوایای 23 و 60 درجه بترتیب دارای کمترین و بیشترین، عمق آبشستگی و فاصله خط القعر از ساحل بیرونی می ¬باشند. حداکثر عمق آبشستگی زوایای 23 و 60 درجه بترتیب 127/0 و 496/0 طول موثر سازه می ¬باشند درضمن فاصله ماکزیمم عمق آبشستگی (خط القعر) زوایای مذکور از ساحل بیرونی بترتیب 743/0 و 6/1 طول موثر سازه می ¬باشد. با افزایش زاویه نصب، فاصله پشته رسوبگذاری شده از ساحل بیرونی و ابعاد آن در پائین دست، افزایش می ¬یابد. در زوایای 23 و 70 درجه فاصله پشته رسوبگذار از ساحل بیرونی بترتیب 267/0 و 39/0 طول موثر سازه میباشد.}, keywords_fa = {آبشکن مثلثی شکل,قوس ملایم 90 درجه,آبشستگی و رسوبگذاری}, url = {http://mcej.modares.ac.ir/article-16-11840-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11840-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {rezaiee-pajand, mohamm}, title = {shape optimization of concrete dams by three approximation methods}, abstract ={optimization of arch dams.}, Keywords = {arch dams,sequential quadratic programing,feasible direction,Sensitivity analysis}, volume = {14}, Number = {3}, pages = {177-188}, publisher = {Tarbiat Modares University}, title_fa = {طرح شکل بهینه ی سدهای دوقوسی بتنی با سه روش تقریبی}, abstract_fa ={سد قوسی یکی از سازه¬های بتنی پرکاربرد و مفید می¬باشد. طرح بهینه¬ی شکل این گونه سدها کمک شایانی به بهره¬وری مطلوب از ظرفیت سازه و مصالح می¬نماید. این پژوهش یک الگوی هندسی مناسب و روشی کارا برای بهینه¬سازی شکل سدهای قوسی پیشنهاد می¬کند. افزون بروارد کردن تمامی محدودیت¬های هندسی ورفتاری سازه دررابطه سازی، کمترین حجم سد حساب می¬شود. از الگوی سد دوقوسی سهمی¬گونه برای هندسه¬ی سازه بهره¬جویی خواهد شد. بهینه¬سازی شکل سدهای دوقوسی بتنی با سه روش تقریبی انجام می¬پذیرد. تجربه¬های عددی این مقاله نشان می دهدکه با وجود به کاربردن متغیرهای طراحی بیشتر، می توان با روش پیشنهادی حجم سازه¬ی کمتری نتیجه گرفت وزمان تحلیل را کاهش داد. سد قوسی یکی از سازه¬های بتنی پرکاربرد و مفید می¬باشد. طرح بهینه¬ی شکل این گونه سدها کمک شایانی به بهره¬وری مطلوب از ظرفیت سازه و مصالح می¬نماید. این پژوهش یک الگوی هندسی مناسب و روشی کارا برای بهینه¬سازی شکل سدهای قوسی پیشنهاد می¬کند.}, keywords_fa = {سد دوقوسی,برنامه ریزی درجه دوم پیاپی,جهت پذیرفتنی,تحلیل حساسیت}, url = {http://mcej.modares.ac.ir/article-16-9236-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9236-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {maadani, saeed and akbari, reaza and maalek, shahrokh}, title = {Comparison of the Vibrational Frequencies of RC Slab-on-Girder Bridge via Theoretical and Experimental methods}, abstract ={In this paper, the dynamic characteristics of two highway bridges have been extracted via performing several operational modal tests. The tests have been performed during the normal traffic passage and ambient condition. The first bridge studied here, the "Ziar-1" Bridge built in 2003s in the road between the cities of Isfahan and Ziar, is a two span reinforced concrete with cast in place slab-on-rectangular girder superstructure system with the total length of 33 m. The deck is simply supported over a wall type middle pier and two side abutments with closed type. The superstructure is supported by the piers and abutments through elastomeric bearings. The second bridge, the "Ziar-2" Bridge built in 2012s as the new line of that road, is a two span reinforced concrete with in-site slab-on-precast girder superstructure system with similar length of the first bridge. The deck of this bridge is continuous without middle or side expansion joints and is supported over a pier bent consisting of a bent cap and three circular columns. The bridges, which pass over the "Zayandeh-Rood" river, are structurally separate and a 50cm distance has been provided between them. Both the bridges have similar geometry but different boundary conditions. The results of the modal tests have been also compared with the results of supporting finite element models of the bridges and the effects of boundary conditions on the dynamic characteristics of the bridges have been investigated. At the time of the first phase experiments, the river was dry due to drought in recent years and the level of underground water was sufficiently deep. It is predicted that presence of water current around bridge piers, in which the superstructure have monolithic connection with piers and side abutments, may change the dynamic properties of superstructure. In order to investigate to what extent the presence of water current in the river may affect the dynamic characteristics of the bridges; additional modal test has been performed on the second bridge, in which its deck is continuously connected to the supporting elements. On the other hand, the seasonal effects of the water current in the river on the dynamic characteristics of one of the bridges, as representative of reinforced concrete slab-on-girder integral bridges, have been also studied. In order to realize to what extent the pier-superstructure connection in this bridge is monolithic, the actual displacement pattern of the measurement points on the superstructure at the pier location has been closely measured and compared with corresponding results of the finite element model of the bridge. The results show that, as far as the boundary conditions of the deck is concerned, it has significant effect on the dynamic behavior and corresponding natural frequencies of the superstructure, especially in the first bending and the first torsional modes. Also, it was found that the presence of water current around the piers of the bridge leads to slightly increase in the natural frequency and the associated damping values of the bridge.}, Keywords = {Dynamic characteristics,ambient vibration test,Boundary conditions,concrete bridges}, volume = {14}, Number = {3}, pages = {189-198}, publisher = {Tarbiat Modares University}, title_fa = {مقایسه فرکانسهای ارتعاشی پلهای تیر و دال بتنی به روشهای تئوری و تجربی}, abstract_fa ={در این مطالعه، مشخصات دینامیکی دو پل بزرگراهی متشکل از عرشه تیر و دال بتنی دارای هندسه مشابه ولی با شرایط مرزی و محیطی متفاوت با انجام چندین آزمایش ارتعاش محیطی استخراج‌شده و نتایج آن مورد بررسی و مقایسه قرار گرفته است. همچنین، از آنجا که پلهای مورد بررسی بر روی رودخانه احداث‌شده‌اند، به کمک نتایج حاصل از انجام آزمایش مودال، اثر فصلی بودن رودخانه و حضور یا عدم حضور آب در بستر رودخانه بر کمیت‌های دینامیکی یکی از این پلها که اتصال عرشه به کوله و پایه های آن به صورت پیوسته می باشد، در دو بازه زمانی متفاوت یعنی زمان خشکی و زمان پر آبی رودخانه، بررسی شده است. به منظور مقایسه شهودی میزان گیرداری و تغییر شکل‌های اتصال پیوسته عرشه به پایه در این نوع پلها، جابجایی های واقعی عرشه، در نزدیک مرز محل اتصال به پایه، اندازه‌گیری و با مدل تحلیلی مقایسه می شود. نتایج حاصل از بررسیهای انجام‌شده نشان می دهد، شرایط مرزی در تکیه گاههای عرشه نظیر صلبیت خمشی اتصال عرشه به پایه و کوله و یا وجود بالشتکهای الاستومری، تأثیر قابل‌توجهی در تغییر فرکانس ارتعاشی مودهای سازه به ویژه مودهای اول خمشی و پیچشی دارد. همچنین مغروق شدن پایه ها در آب نیز موجب تغییرات ناچیز در مقادیر فرکانسهای ارتعاشی و تغییرات بیشتری در مقادیر میرایی سازه می گردد.}, keywords_fa = {مشخصات دینامیکی,ارتعاش محیطی,شرایط مرزی,پلهای بتنی}, url = {http://mcej.modares.ac.ir/article-16-9942-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9942-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Aghajani, A. and Golozar, M.A. and Saatchi, A. and Shabani, S.}, title = {AC Stray Current and Environmental Effects on Concrete Power poles}, abstract ={The purpose of this article is study of effects of high voltage AC stray current (380 VAC) and environmental effects on durability of concrete power poles. In Iran, annually spend large costs for replacing them with new concrete poles. In this study, the degradation effects and mechanisms of 380 VAC stray current on water saturated concrete were investigated via field and laboratory tests. They included electrical and electrochemical tests and microscopic inspections. Based on the results of tests both environment and AC stray current reduce durability of the concrete power poles. Formation of galvanic macro cell, carbonation, vibration of concrete pole due to wind force and weight of cable, diffusion of corrosive ions from soil to concrete power pole and its accumulation in near ground level are some of environmental effects on degradation of concrete power poles. In addition pollution of air can form deposit layer on insulations of concrete power pole. In raining condition, the layer absorbs water and surface resistance of insulators reduces considerably. So high voltage AC current can creep in surface of the insulator and can exchange between two other phases and ground. Generally grounding system can't act immediately or have not suitable low electrical resistance. Meanwhile if concrete of power pole has low quality then it absorbs high content of rain and its resistivity decreases considerably. Thus some parts of fault current can pass through water saturated concrete power pole. In an special location around Isfahan with polluted air condition, in raining condition current creep through the surface of some insulators occur and immediately many cracks forms on concrete cover of power pole and in some cases concrete cover start to fall without any corrosion in rebar. Based on field study, AC stray current does not occur in concrete power poles which manufactured by centrifugal method and they have very low w/c ratio in their mix design. In this method excess water of concrete mix is removed before staring curing of concrete. Microscopic study of concrete of the molded pole and centrifugal pole showed that the later had much denser structure and for this reason depth of carbonation in the later was much lower than the first. In addition the centrifugal poles have pre-stress condition and it reduce their vibration against wind force and weight of cables. Vibration has destructive effect on concrete cover of concrete poles, special in their ground level because force of vibration concentrates in this location. For study mechanism of degradation of AC stray current, some concrete samples prepared and in water saturated condition subjected to 380 VAC stray current. Based on results of tests, high voltage AC stray current can reduce the concrete pole durability by thermal and shrinkage stress and also by creating vapor pressure within water saturated concrete and transport calcium hydroxide toward cement paste-aggregate interfaces. Application of new technology for reducing water to cement ratio and proper installation and maintenance of the concrete poles considerably increases durability of them against destructive effects of AC stray current.}, Keywords = {Concrete pole,durability,Stray current}, volume = {14}, Number = {2}, pages = {1-12}, publisher = {Tarbiat Modares University}, title_fa = {آثار جریان سرگردان متناوب و عوامل محیطی بر تیرهای بتنی توزیع برق}, abstract_fa ={هدف این مقاله بررسی آثار جریان سرگردان متناوب در 380 ولت و نیز آثار عوامل محیطی بر دوام تیرهای بتنی توزیع برق است     . در این پژوهش ساز و کار تخریب تیرهای بتنی به کمک آزمون های الکتریکی، الکتروشیمیایی و بررسی ساختار بتن بررسی شده است     . بر اساس نتایج آزمون های انجام شده، جریان سرگردان متناوب در ولتاژهای بالا و نیز آثار عوامل محیطی باعث کاهش دوام تیرهای بتنی می شود     . مکانیزم تخریب بتن به وسیله ی جریان سرگردان متناوب از طریق توزیع غیر یکنواخت جریان، ایجاد تنش های حرارتی و انقباضی، افزایش دما و ایجاد فشار بخار در داخل بتن و انتقال مواد از طریق محلول حفره های مویین به   فصل مشترک سیمان     -شن و ماسه است. به کارگیری فناوری های جدید در ساخت تیرهای بتنی به منظور کاهش نسبت آب به سیمان و نصب صحیح و رعایت اصول نگه داری آنها موجب افزایش قابل ملاحظه مقاومت آنها در برابر آثار جریان سرگردان متناوب   خواهد شد       .  }, keywords_fa = {تیر بتنی,دوام,جریان سرگردان}, url = {http://mcej.modares.ac.ir/article-16-941-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-941-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Ouhadi, V.R. and Amiri, M. and Hamidi, S.}, title = {Dispersive soil improvement with lime, special attention to the reduction of peak intensity of clay minerals in XRD analysis}, abstract ={Civil engineering projects usually require an improvement on soil properties. In this case, the improvement of soil strength, permeability, and erosion resistance, collapsible or dispersive behaviour might be important. Consequently, engineers are always willing to achieve an optimum way to stabilize/improve soil performance for practical applications. Generally, the presence of dispersive clays in engineering projects is one of the essential problems for civil engineers. Several failures in engineering projects due to the presence of dispersive soils are reported in different parts of the world. In spite of several researches on this subject, there has been little attention to the microstructure of stabilized dispersive soils. In this paper the improvement of properties of a natural dispersive soil is studied with special attention to the solubility of clay mineral peaks in XRD analysis and formation of aluminates and silicates minerals after lime application to dispersive soil. The soil sample of this area is silty clay which has 100% dispersivity potential. Several geotechnical erosions are reported in this area which is attributed to the presence of dispersive soils. Due to the low bearing capacity of soil, and to overcome to its dispersivity behaviour, the application of lime is chosen as soil stabilization means. In this paper, at the first step with application of double hydrometer and cation exchange capacity experiments, the dispersive potential of soil is determined. In addition, the major minerals of soil are addressed by the use of XRD analysis. For the dispersive soil sample, the major geotechnical properties of soil including unconfined compression test, settlement behaviour, and over consolidation stress are measured and reported. Then, the soil sample is mixed with lime and water. After equilibrium and after curing process, several geotechnical and geo-environmental experiments were performed on soil samples to investigate on the dispersivity potential variations of soil. Furthermore, the microstructure of lime treated dispersive soil was monitored by application of XRD analysis on lime treated soil. The results indicate that the dispersivity potential of soil disappears after application of 6% of lime. In this process the dispersive structure of soil changes to the more flocculated structure. Moreover, the results of XRD analysis indicate that following application of lime, parts of clay fraction solubilize, leading to the formation of pozzolanic components. The main conclusion of this paper is the determination of the required percentage of lime for soil stabilization with the application of micro-structural experiments and with the measurement of the quantity of increase in over-consolidation stress. With the performance of several consolidation tests on untreated and lime-treated dispersive soil, it is shown that with application of 6% lime, an increase of 430% in over-consolidation stress is observed. This means for each percent of lime a 50 kN/m 2 increase in over-consolidation stress is achieved.}, Keywords = {Dispersivity,Solubility of Clay Minerals,lime,Over-Consolidation Stress,XRD}, volume = {14}, Number = {2}, pages = {13-25}, publisher = {Tarbiat Modares University}, title_fa = {بهسازی خاک های واگرا با آهک با نگرش ویژه به کاهش شدت قله های اصلی کانی های رسی در پراش پرتو ایکس}, abstract_fa ={وجود خاکهای واگرا در محل اجرای سازههای مهندسی، از مشکلات اساسی در برخی از پروژههای عمرانی است   .   پژوهش حاضر به مطالعه بهبود خصوصیات مهندسی خاک واگرای طبیعی با نگرش ویژه به تغییرات ریز ساختاری و حل شدگی قله های اصلی کانیهای رسی و تشکیل ترکیبات جدید می پردازد . خاک مورد مطالعه دارای 100 % پتانسیل واگرایی است. در این پژوهش ابتدا پتانسیل واگرایی خاک تعیین شده، و سپس خصوصیات مهم ژئوتکنیکی خاک مطالعه شده آزمایشگاهی قرار گرفته       -   است . در ادامه، خاک مطالعه شده با آهک شکفته مخلوط شده و بعد از پایان دوره عمل آوری، نمونهها تحت آزمایشهای مختلف ژئوتکنیکی قرار گرفته و میزان تغییرات پتانسیل واگرایی و بهبود ویژگی های مهندسی خاک ارزیابی شده قرار گرفتهاست     . همچنین روند تغییرات ریزساختاری نمونهها شامل حل شدگی کانیهای رسی و تشکیل ترکیبات جدید در اندرکنش خاک واگرا و آهک   تحلیل شدهاست     . نتایج نشان میدهد که پتانسیل واگرایی در نمونههای تثبیت شده کاملاً حذف شدهاست. همچنین نتایج آزمایش مقاومت فشاری محدود نشده و تحکیم نشان دهنده افزایش مقاومت و کاهش میزان ضریب فشردگی است     . بر اساس نتایج ارزیابی پراش پرتو ایکس علت اصلی بهبود خواص مکانیکی حل شدگی کانی های رسی، واکنشهای پوزولانی و تشکیل ترکیبات   سیلیکاتی و آلومیناتی کلسیم است     . مهمترین نتیجه پژوهش حاضر را میتوان تعیین درصد بهینه آهک بر اساس میزان افزایش تنش   % پیش تحکیمی و آزمایشهای ریز ساختاری بیان نمود، که به ازای افزودن 6 درصد آهک میزان تنش پیش تحکیمی حدود 430 50     افزایش نشان دادهاست. (kN/m افزایش یافته و به ازای هر درصد آهک تنش پیش تحکیمی حدود  }, keywords_fa = {واگرایی,حل شدگی کانیهای رسی,آهک,تنش پیش تحکیمی XRD:}, url = {http://mcej.modares.ac.ir/article-16-4849-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-4849-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Larimi, S.N. and Ayati, B.}, title = {Use of Walnut and Peanut Shells Activated Carbon in Direct Blue71 Removal: Kinetic and Isotherm}, abstract ={Most of dyes used in production processes caused serious environmental pollution when discharged to the water resources. Azo dyes are the most used synthetic compounds in the industries such as textile, food, leather and cosmetic. Due to their toxicity and hard degradation, these kinds of compounds are classi fied as environmental hazardous materials that have to be treated before discharging to the environment. Direct blue 71 (DB 71) is one of azo dyes that is resistant to aerobic degradation and under anaerobic condition is reduced to potential carcinogenic aromatics. Different kinds of physical, chemical and biological methods such as adsorption, ultra filtration, reverse osmosis, coagulation and electro coagulation are widely used for efficient dye removal but they just transport contaminants from water to sludge and generate secondary wastes which need more treatment. Adsorption with many advantages is a proper method that is applied to treat dye compounds. In recent years, use of low cost materials as adsorbent for dye removal has been highlighted. Since natural absorbents are inexpensive and may be achieved without any cost and they are usually in abundance in nature, absorption of solute ions by these materials are a proper method to eliminate color from polluted waters and industrial wastewaters. In this study, removal of azo dye Direct Blue 71 was evaluated with two new natural adsorbents of walnut and peanuts shells. These adsorbents are produced from agricultural wastes. The effect of pH, contact time and adsorbent dosage on the removal efficiency has been studied. According to the results, maximum removal of dyes by the two natural absorbents (0.75 gr/L walnut shell in 50 mg/L initial dye concentration with pH of 9 in 45 minutes and 1 gr/L peanut shell in 50 mg/L initial dye concentration with pH of 9 in 60 minutes) was 55 and 60 percent, respectively. Comparison of prepared adsorbent in the laboratory and commercial ones in optimum condition have similar dye removal efficiency that means suitable and cheap adsorbent could be prepared in the laboratory. Removal efficiency of DB71 was also obtained 85 and 83 by the two walnut and peanut shells adsorbent powder, respectively. The results have also shown that amongst four isotherms of Langmuir, Freundlich, Temkin and Dubinin-radushkevich, Freundlich isotherm has the highest correlation coefficient which implying heterogeneous surface of adsorbent for both sorbents. It has also shown that the maximum surface adsorbent capacity for the monolayer of activated carbon of the walnut and peanut shells were 26 and 28 mg/gr, respectively. From the n values 3.58 and 3.72 of the Freundlich isotherm for both adsorbent of walnut and peanut shells, it could be concluded that physical adsorption process has been happened. The data could also indicate that pseudosecond- order was the best adsorption kinetics model for the two adsorbents}, Keywords = {pH,pH,dye concentration,adsorbent dosage,activation}, volume = {14}, Number = {2}, pages = {27-37}, publisher = {Tarbiat Modares University}, title_fa = {کاربرد کربن فعال پوسته های گردو و بادام در حذف رنگزای آبی مستقیم 71 : سینتیک و ایزوترم جذب}, abstract_fa ={رنگزاهای موجود در پساب خروجی از صنعت نساجی شامل طیف وسیعی از آلاینده ها و ترکیب سمی و سخت تجزیه پذیر بوده که سبب اختلال در محیط زیست میشود . استفاده از جاذبهایی مانند پوستههای گردو و بادام که سالانه قسمت وسیعی از ضایعات کشاورزی را شامل میشود، روشی مناسب برای تصفیه فاضلاب این صنعت است     . در این پژوهش از پوستههای زمان تماس و ،     pH استفاده شد و اثر عوامل Direct Blue 0/4 ) به عنوان جاذب در حذف رنگزای 71 -2/38 mm) گردو و بادام دانهای معادل     pH دوز جاذب بر میزان راندمان حذف بررسی شد. بیشینه راندمان حذف رنگزای مورد نظر به وسیله ی جاذب پوسته گردو در   pH 50 در مدت زمان 45 دقیقه و در حضور جاذب پوسته بادام در mg/L 0 گرم بر لیتر با غلظت اولیه رنگزا برابر / 9 با دوز جاذب 75 50     در مدت زمان 60 دقیقه به ترتیب برابر 55 و 60 درصد به mg/L معادل 9 با دوز جاذب 1 گرم بر لیتر با غلظت اولیه رنگزا برابر دست آمد     . در پایان شرایط بهینه حذف رنگزا بر روی هر کدام از جاذبهای تهیه شده در آزمایشگاه و جاذبهای پودری پوسته های گردو و بادام انجام شد و نتایج حاصل با کربن فعال دانهای تجاری خریداری شده مقایسه شد     . با بررسی نتایج حاصل در زمان تعادل با مدلهای ایزوترم لانگمایر، فرندلیچ، تمکین و دوبینین     - رادوشکویچ و با توجه به بیشترین ضریب همبستگی مشخص شد که دو جاذب پوستههای گردو و بادام از مدل ایزوترم فرندلیچ و تمکین تبعیت میکنند که نشاندهنده ناهمگن بودن سطح جاذب است       . 28     به mg/gr 26 و mg/gr حداکثر ظرفیت جذب سطحی تک لایه کربن فعال حاصل از پوستههای گردو و بادام به ترتیب در حدود دست آمد     . سینتیک جذب سطحی دو جاذب نیز از مدل سینتیکی شبه مرتبه دوم تبعیت نمود .  }, keywords_fa = {غلظت رنگزا,غلظت جاذب,فعالسازی}, url = {http://mcej.modares.ac.ir/article-16-4854-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-4854-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Paseh, H.R. and Oliaei, M.}, title = {Based Performance Evaluation of Earth Dams under Seismic Loading}, abstract ={Dams shall safely retain the reservoir and any stored solids, and pass environmentally acceptable flows, as required for all loading conditions, ranging from normal to extreme loads, commensurate with the consequences of failure. The new trend for performance-based design is to consider 2 levels of seismic actions and analyze the situation where the limit of force balance is exceeded for high intensity ground motions, associated with a very rare seismic event. For the design, two basic requirements are defined: (i) Non-collapse requirement (ultimate limit states), i.e. after the occurrence of the seismic event, the structure shall retain its structural integrity, with respect to both vertical and horizontal loads, and adequate residual resistance, although in some parts considerable damage may occur, (ii) Minimization of damage (serviceability limit state) , i.e. after seismic actions with high probability of occurrence, during the design life of the structure, some parts can undergo minor damage without the need of immediate repair. This study evaluates the behavior of a typical earth dam by nonlinear seismic analyses, in two performance levels, named “Base Performance Level” and “Desired Performance Level.” The level of seismic action and related acceptance level of damage are defined for each performance level. In “Base Performance Level,” with seismic levels of OBE (0.3g) and MDE (0.5g), the structure shall be serviceable and repairable and in “Desired Performance Level”, with seismic levels of MDE (0.5g) and MCE (0.7g), the structure shall be serviceable and repairable, respectively. Also, the stability of dam has been assessed by the “Strength Reduction Analysis.” The analyses are nonlinear and the constitutive law of the materials was assumed to follow "Finn" and "Mohr-Coulomb" models, incorporated into “FLAC 2D” finite difference analysis program. The factors such as initial shear modulus, variation of shear modulus versus shear strain, generation and dissipation of pore pressure and hysteretic damping are considered in this study. In addition, using the scaling method of applying maximum acceleration, the response of dam is investigated in different maximum accelerations. The results show that the dam needs to be changed in geometrical specifications or seismically improved in “Desired Performance Level”, in contrast with “Base Performance Level.” Results are confirmed by low amount of safety factors of stability in dam, which are calculated for different seismic loads. Also, the behavior of dam is examined by sensitivity analysis for type of accelerograms, constitutive model and the standard penetration number in shell of dam. Two accelerograms, including “Friulli” and “Sakaria” are considered. Maximum acceleration and duration of both of them are equalized and frequencies more than 5Hz are filtered. Sensitivity analyses of “Friulli” and “Sakaria” accelerograms, despite the difference in response spectra and specific energy density, show approximately similar results. “Finn” model predicts the amount of excess pore water pressure to be more than "Mohr- Coulomb" up to %20, and shows the occurring of liquefaction in SPT more than 35 and acceleration more than 0.7g, in shell of upstream of dam}, Keywords = {earth dam,Based Performance Evaluation,nonlinear dynamic analysis,Finn Model,SRF Analysis}, volume = {14}, Number = {2}, pages = {39-53}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی مبتنی بر عملکرد رفتار سدهای خاکی تحت بارگذاری زلزله}, abstract_fa ={در این پژوهش، رفتار یک سد خاکی نوعی در دو سطح عملکردی، موسوم به سطح عمکرد "مبنا " و "مطلوب " ، با انجام تحلیلهای دینامیکی غیرخطی ارزیابی شده که، در هر سطح عملکرد، سطوح لرزهای معین و سطوح تخریب مجاز متناظر   تعریفشدهاست     . همچنین، رفتار سد برای عواملی مانند شتابنگاشت ورودی، مدل رفتاری و عدد نفوذ استاندارد پوسته حساسیت -   بررسیشدهاست . نتایج نشان میدهد که الزامات (SRF سنجی و پایداری سد با انجام تحلیلهای کاهش پارامترهای مقاومتی ( تحلیل عملکرد     "مبنا" برای سد مطالعه شده با توجه به ویژگیهای هندسی و ژئوتکنیکی آن قابل تامین است. اما تأمین عملکرد "مطلوب "   برای این سد، مستلزم ایجاد تغییرات در ساختار سد و یا بهسازی لرزهای آن است . وجود ضرایب اطمینان پایین در سطوح لرزهای مطالعه شده، این مطلب را تایید می کند     . تحلیلهای حساسیتسنجی به شتابنگاشتهای "فریولی" و "ساکاریا" ، باوجود تفاوت در پاسخ طیفی و چگالی انرژی آنها، نتایج یکسانی را ارائه مینماید     . مدل فین بسته به تراز شتاب بیشینه اعمالی، فشار آب حفره ای اضافی ایجاد شده در بالادست سد را     20 درصد بیشتر از مدل رفتاری مور- کولمب پیشبینی مینماید. با تغییر عدد نفوذ استاندارد پوسته و تحلیل سد در شتابهای بیشینه مختلف مشاهده می شود که مدل فین در اعداد نفوذ استاندارد اصلاح شده کمتر از     35 و در   0/7 ، وقوع پدیده روانگرایی را در خاکریز بالادست سد پیشبینی مینماید .  }, keywords_fa = {سد خاکی,ارزیابی مبتنی بر عملکرد,تحلیل دینامیکی غیرخطی,مدل فین,تحلیلSRF}, url = {http://mcej.modares.ac.ir/article-16-3997-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-3997-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Hosseini, S.Zh. and Ahmadi, M.T.}, title = {Seismic sensitivity evaluation of concrete buttress dams}, abstract ={Concrete buttress dams are constructed in large numbers at medium sites in many countries such as Iran because of their considerable technical and economical benefits in previous century. This type of dams is exposed to damages due to earthquakes as other structures. Some buttress dams such as Sefidroud dam in Iran, Hsinfengkiang dam in China and Honenike dam in Japan have undergone some damages due to recent earthquakes. After these incidents, some investigations have been carried out. However, these investigations have just mentioned the manner of incidents and the resulting damages. Therefore, the seismic behavior and sensitivity recognition of these dams with respect to different factors have been ignored; however the study of behavior and seismic sensitivity of this type of dams is important. In this paper, the tallest monolith of the Sefidroud concrete buttress dam is analyzed using a 3D model with massless foundation to study the seismic behavior and sensitivity of this type of dam. The interaction of the dam with the reservoir, the reservoir bottom absorption and upstream radiation of hydrodynamic waves are considered, but the cross-canyon component of earthquake is neglected. The applied accelerograms to the system are scaled according to the Sefidroud dam site DBE response spectrum. To determine the initial conditions before occurring earthquake, a series of detailed static analyses are done under the effect of dam body weight, hydrostatic pressure, uplift pressure and ambient temperature. Seismic loading due to longitudinal and vertical components of earthquake is applied and the nonlinear behavior of dam under various factors such as different seismic loading scenarios and different properties of dam body and also foundation materials is investigated. The results of analyses show that the dam body downstream kink, heel, toe and buttress web are sensitive and vulnerable zones. The results also demonstrate that the compressive stresses in the dam body are usually much less than the compressive strength of concrete. Therefore, the possibility of compressive failure is almost zero. But the conditions of tensile and shear stresses are different and large stresses may occur at the mentioned zones and considerable tensile and shear damages to the dam body are possible. According to the results of analyses, it is apparent that when the ratio of dam body modulus to that of the foundation (called softness modulus) is small, i.e. when the foundation modulus is high and near to that of dam body, the construction of concrete buttress dams at highly seismic zones may cause local failure and unfavorable situations for the tensile stresses at the kink, the heel and the toe of the dam body. Therefore, adaptation of this dam type in such sites should be carefully studied and in these circumstances, the modulus of the concrete of dam body should be kept more than usual practice. Furthermore, the shear damage at the dam-foundation contact surface is highly dependent to the applied earthquake type, but increasing the softness modulus could reduce this type of damage. The compressive strength of concrete has no effect on the shear damage at the dam-foundation contact surface.}, Keywords = {concrete buttress dam,Sensitivity analysis,nonlinear dynamic analysis,seismic vulnerability,Sefidroud dam}, volume = {14}, Number = {2}, pages = {55-66}, publisher = {Tarbiat Modares University}, title_fa = {بررسی حساسیت لرزه ای سدهای بتنی پشت بنددار}, abstract_fa ={بلند ترین پایه ی سد بتنی پشتبنددار سفیدرود به صورت سه بعدی تحت اثر مولفه های طولی و قائم زلزله ی در دره ی ساختگاه سد تحلیل شده است . اندرکنش سد با پی و مخزن و جذب امواج هیدرودینامیک در کف و انتهای مخزن در نظر گرفته شده اند     . شتاب نگاشت های اعمالی به سازه با توجه به شرایط ساختگاه سد سفیدرود مقیاس شده ، و برای تعیین شرایط اولیه ی قبل از وقوع زلزله، یک سری تحلیل های استاتیکی تفصیلی انجام شده اند و سپس بارگذاری دینامیکی تاریخچه ی زمانی ناشی از زلزله ی   طولی و قائم در دره ی ساختگاه سد صورت گرفته و رفتار غیرخطی سد در برابر عوامل مختلف، مانند حالت های مختلف بارگذاری   لرزه ای، مشخصات مصالح بدنه ی سد و پی، بررسی شده است     . نتیجه تحلیل ها آن است که چهار منطقه ی اصلی از بدنه ی سد شامل محلِ تغییرِ شیبِ بدنه در پایاب از نظر کششی، پاشنه ی سد از نظر کششی، پنجه و لبه ی پشتبند سد به ویژه از نظر فشار و برش،   مناطق حساس و آسیب پذیر سد می باشند     . البته تحلیل ها نشان می دهد که احتمال شکست کششی در بیشتر نقاط حساس مذکور در بدنه با افزایش مقاومت فشاری بتن کاهش پیدا می کند     . ودر صورت نرمی زیاد پی، تنش های فشاری لرزه ای در پنجه ی سد افزایش زیادی دارند که گرچه معمولاً کمتر از مقاومت فشاری بتن باقی می مانند، ولی ممکن است منجر به شکست سنگ پی ضعیف شود       .   نکته قابل توجه دیگر این که هرقدر پی سد بتنی پشتبنددار، سخت تر باشد، در ساختگاه های لرزه خیز شکست موضعی در محل تغییر شیب پایاب، پاشنه و پنجه ی سد محتمل تر است . پس توصیه می شود در چنین شرایط از بتنی با مدول ارتجاعی بالاتر از حالات عادی برای بدنه ی سد استفاده شود       .  }, keywords_fa = {سد بتنی پشتبنددار,تحلیل حساسیت,تحلیل دینامیکی غیرخطی,آسیب پذیری لرزه ای,سد سفیدرود}, url = {http://mcej.modares.ac.ir/article-16-7819-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7819-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Zahrai, S.M. and Biglarian, R.}, title = {Seismic performance assessment for hybrid system of tuned mass & liquid column damper in series and a method to increase efficiency}, abstract ={In recent years, development of effective devices for seismic energy dissipation in structures has become more important to keep response of structure in elastic range. Dampers are used in structures to reduce response and effect of seismic forces. Also, using secondary mass technology can help seismic energy dissipation. Among these systems one can mention tuned mass damper and tuned liquid column damper, working base on secondary inertia in structures. In this paper, hybrid system of tuned mass & liquid column dampers in series was considered with mass ratios 0.035-0.005, 0.03-0.01 and 0.02-0.02. Time history analysis using the Northridge, Tabas and Loma Prieta earthquakes for 20 story structures were modeled in Simulink Matlab software considering shearing structure and damper modeling in every blocks separately. Effect of damper to structure is determined as forces applying on corresponding story. Performance indices using software outputs such as root mean square and Maximum of displacement and acceleration of stories were calculated. Performance of single and hybrid systems has been compared due to different earthquakes. Also effect of hybrid systems in series was studied by increasing head loss coefficient. Results show that performance of hybrid systems is dependent on earthquake characteristics that improves with increasing secondary mass ratio. For example under the Northridge earthquake, hybrid system in series tuned mass & liquid column damper with mass ratios 0.035-0.005, 0.03-0.01 and 0.02-0.02 decrease root mean square of displacement of stories 45, 27 and 2 percent respectively and also by selecting optimum frequency ratio based on responses of structure. For example maximum acceleration of hybrid system of tuned mass & liquid column damper in series with mass ratio 0.035-0.005 is optimum frequency ratio in 2.9 and also by selecting this frequency ratio decrease maximum acceleration of up and down stories in 20 story structure. By comparing effects of hybrid system Tuned Mass & Liquid Column Damper in series with different mass ratios on two structures with periods of 1.5 and 2.44 second are considering where by increasing stiffness of structure, performance of hybrid system was improved leading to decrease of acceleration responses and reduction of displacement responses. For example, J1 in 20 story structure with period 1.5 second is 0.71 whereas in other structure is 0.79 that show hybrid system has better performance in structure with period 1.5 second. Hybrid system in series damper with mass ratio 0.035-0.005 have best performance to reduce displacement stories of 20 story structure with period 1.5 second as J3=0.56 means decrease 44%. Also in other structure, hybrid system with mass ratio 0.035-0.005 has best performance to reduce displacement at top floor with J4=0.56. Also performance of hybrid system to reduce maximum displacement of stories was improved by increasing head loss coefficient in tuned liquid column damper}, Keywords = {Hybrid system in series Tuned Mass & Liquid Column Damper,passive control,Optimum Frequency Ratio}, volume = {14}, Number = {2}, pages = {71-83}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی عملکرد لرزه ای سیستم ترکیبی سری میراگر جرمی و ستون مایع و ارائه روشی برای افزایش کارایی آن}, abstract_fa ={در سال های اخیر به توسعه وسائل مؤثر در استهلاک انرژی لرزه ای در سازه ها اهمیت بیشتری داده شده است که پاسخ سازه اصلی را در ناحیه الاستیک نگه دارند . به این منظور، میراگرها برای کم کردن اثر نیروی زلزله به سازه ها استفاده م ی شوند .   همچنین تکنولوژی هایی برای استهلاک انرژی لرزه ای با قرار دادن جرم کمکی توسعه پیدا کرده است   . 0     و /01-0/03 ،0/005-0/ در این مقاله، سیستم ترکیبی سری میراگر جرمی و ستون مایع تنظیم شده با نسبت های جرمی 035 0/02-0/02     در نظر گرفته شده است. تحلیل تاریخچه زمانی بر روی سازه های 20 طبقه تحت زلزله های نرتریج، طبس و لوما پرایتا   0.4 با استفاده از نرم افزار شبیه سازی مطلب انجام شده است. عملکرد سیستم های ترکیبی سری با سیستم تک میراگر g مقیاس شده به ستون مایع مقایسه شده و همچنین کارایی سیستم های ترکیبی سری با افزایش ضریب افت هد بررسی شده است     . نتایج حاکی از آن است که عملکرد سیستم ترکیبی سری وابسته به مشخصات زلزله های مختلف، فرق می کند و با افزایش نسبت جرمی جرم دوم و نیز   با انتخاب نسبت فرکانسی بهینه بر اساس پاسخ ها، کارایی میراگر ترکیبی سری افزایش می یابد       .  }, keywords_fa = {سیستم ترکیبی سری میراگر جرمی و ستون مایع تنظیم شده,کنترل غیرفعال,نسبت فرکانسی بهینه}, url = {http://mcej.modares.ac.ir/article-16-9462-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9462-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Souri, A. and Shahbeyk, S. and Rahiminejad, D.}, title = {A Numerical Study on the Uniaxial Mechanical Properties of Metal Foams with Spherical Cellular Structure}, abstract ={Metal foams as a new class of materials with interesting properties such as high stiffness and strength to density ratios, capacity to absorb impact energy, and reproducibility, are rapidly growing their share in advanced materials market. However, due to their porous microstructure, experimental investigations of their properties are not trivial and normally need rigorous procedures and high end equipments. Accordingly, there is a growing research interest towards the numerical modeling of their cellular structure in which the following three kinds of models have been commonly employed: (1) structures based on a unit cell or a building block, (2) random Voronoi diagrams, and (3) CAD data provided by Xray micro-computed tomography. In the current study, the mesostructure of aluminum foam produced by the brazing technique is simulated as a connected assembly of spherical shells. The latest inward packing scheme from the set of constructive algorithms is incorporated to efficiently pack the spheres in space. The Gamma distribution is used to control the cell diameters. Three mean values of 3, 4, and 5 mm and two variances of 0.5 and 1.0 mm are assumed for the radii of spheres and cubic specimens of 50 mm are generated. Two assumptions of constant thickness and constant thickness to radius ratio have been applied to the spherical shells. Two relative densities of 0.05 and 0.1 have been examined in the current study. A code is written to automatically transfer these geometrical data to ABAQUS FE program. The models are then meshed in 1 mm S4R shell elements. Tie contacts are defined between neighbor spheres. Furthermore, self contact is used to prevent any probable penetrations in the models. The foaming material is assumed to be AL 3003 H12 with elastic-perfectly plastic behavior. Next, the uniaxial load is applied by means of two rigid planes and the stress-strain curves are extracted. Main attention has been paid to the elastic modulus and initial yield stress of foam. It is observed that keeping the mean value of the radius and increasing its variance lead to the generation of more small spheres within the microstructure which itself increases the number of interactions inside the foam and thus increases elastic modulus and yield stress. The results also show that, for both thickness assumptions made here, increasing the mean radius of spheres decreases the number of spheres and their interaction points and subsequently weakens their uniaxial mechanical properties. Furthermore, compared to foams generated based on the constant thickness to radius ratio assumption, the presence of thick small spheres in foams with cells of constant thickness makes them stiffer and stronger. This effect is more pronounced in foam with higher densities}, Keywords = {Closed-cell metal foam,Brazing,Microstructure,finite element method,Gamma Distribution}, volume = {14}, Number = {2}, pages = {85-93}, publisher = {Tarbiat Modares University}, title_fa = {بررسی عددی خواص مکانیکی تک محوری فوم های فلزی با ساختار سلولی کروی}, abstract_fa ={فومهای فلزی به دلیل داشتن ترکیبی از خواص مناسب مانند نسبت سختی و مقاومت به وزن بالا، امکان جذب انرژی ناشی از برخورد و یا انفجار و قابلیت بازیافت، به سرعت در حال گسترش در کاربردهای مهندسی است و در هر سازهای که استفاده شوند این خواص را برای آن به ارمغان می آورند . یکی از روشهای تولید چنین موادی استفاده از روش بریزینگ است که در آن ابتدا پوسته های کروی فلزی در کنار هم قرار گرفته و سپس با فرآیندی مشابه لحیم کاری به هم متصل میشوند و تشکیل فومی با   ساختار سلولی بسته میدهند     . این پژوهش قصد دارد با شبیهسازی ریزساختار چنین فومهایی به روش اجزای محدود غیرخطی، به مطالعه رفتار تک محوری فشاری آنها بپردازد و اثر توزیع اندازه ی سلولهای ریزساختار و همچنین ضخامت جداره سلولی را بر   مقاومت و سختی ماده بررسی کند       .  }, keywords_fa = {فوم فلزی سلول بسته,بریزینگ,ریزساختار,روش اجزای محدود,توزیع گاما}, url = {http://mcej.modares.ac.ir/article-16-1709-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1709-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Fakhri, M. and Brazvan, S.}, title = {Correlation of LWD, CBR and Cyclic-Triaxial Tests}, abstract ={The resilient modulus of subgrade is an important factor in pavement design which is determined by cyclic triaxial test on cylindrical samples. Due to test complication and difficulties, other tests could be useful if there is an appropriate correlation between results. Nowadays non-destructive testing of pavement is growing in the world as they are rapid, without destruction and have precision measuring equipment. In recent years the application of LWD has been widely developed. This device evaluates pavement structure of several locations in short time with high accuracy. The main objective of this paper is to evaluate the LWD feasibility in order to estimate subgrade resilient modulus and the quality control of construction. So the in-construction road path have been chosen, then LWD field test, CBR laboratory test and finally cyclic triaxial have been done. Also the compaction percentage of each point determined to compare with LWD results. Comparing modulus obtained from LWD results to other test lead to establish models and equation which the best relation between LWD modulus and resilient modulus acquired. Also LWD result scattering is less than CBR. Moreover LWD device has enough efficiency for structural evaluation of unbound material and quality control of pavement sublayers}, Keywords = {CBR,LWD,LWD,CBR,Cyclic Triaxial,Resilient modulus}, volume = {14}, Number = {2}, pages = {95-103}, publisher = {Tarbiat Modares University}, title_fa = {بررسی همبستگی نتایج آزمایش های و سه محوری سیکلی CBR ،LWD}, abstract_fa ={مدول برجهندگی خاک بستر یکی از پارامترهای مهم در طراحی روسازی است که با انجام آزمایش سه محوری سیکلی روی نمونه های استوانه ای به دست می آید . با توجه به پیچیدگی و مشکلات این آزمایش، انجام آزمایش های میدانی به شرط وجود همبستگی مناسب بسیار مفید خواهد بود     . امروزه کاربرد آزمایش های غیرمخرب روسازی در جهان رو به گسترش است . سرعت بالای انجام آزمایش، دقت زیاد تجهیزات اندازه گیری، غیرمخرب بودن و پوشش نقاط بیشتر در سطح راه، عمده دلایل استقبال از   توسعه پیدا کرده است     . این د ستگاه LWD آزمایش های غیرمخرب است. در سال های اخیر کاربرد دستگاه غیرمخرب و قابل حمل قادر است در زمانی اندک و با دقت بالا، نقاط مختلف لایه اجرا شده را از نظر سازه ای ارزیابی کند     . هدف اصلی این پژوهش به منظور تخمین مدول برجهندگی بستر روسازی و کنترل کیفیت اجرای آن است     . LWD امکان سنجی انجام آزمایش میدانی با دستگاه سه     CBR ،LWD بدین منظور یک محور در مرحله اجرای بستر روسازی برای انجام آزمایش های پژوهش انتخاب شد و آزمایش های مقایسه شود     . پس از بررسی نتایج LWD محوری سیکلی بر روی مصالح انجام شد. همچنین تراکم هر نقطه اندازه گیری شد تا با نتایج و سه محوری سیکلی وجود دارد     . همچنین پراکندگی LWD مشخص شد ارتباط خوبی بین نتایج آزمایش های پژوهش به خصوص به منظور کنترل کیفیت لایه بستر بسیار مناسب است       .  }, keywords_fa = {محوری سیکلی,مدول برجهندگی}, url = {http://mcej.modares.ac.ir/article-16-2210-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2210-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Golafshar, A. and Daneshjoo, F.}, title = {Drawing Capcity Spectrum and Determining of Target Displacement without Control Point For Horizontally Curved Bridges}, abstract ={Nonlinear Static pushover (NSP) analysis has become a popular tool for the seismic assessment of buildings and bridges. One of the well-known methods to determine the target displacement during NSP is Capacity Spectrum Method (CSM).In the Conventional CSM, capacity spectrum is drawn based on the location of control point to determine the target displacement. Because of dependency of displacement capacity spectrum on the location of control point, determination of displacement capacity spectrum needs further evaluation and can be time consuming specially for complicated structures. Previous studies have been proposed different choices for location of control point in the bridges such as the point with the maximum displacement or the top point of critical pier. In this paper the CSM has been developed for drawing capacity spectrum. The proposed method is based on determination of displacement capacity spectrum from pushover analysis of MDOF system without selection of any control point. The proposed method is based on derivation of frequency of SDOF system based on current situation of MDOF system for each mode and step. Moreover, nonlinear behavior of MDOF system is considered in frequency of SDOF system step by step. After derivation of frequency of SDOF system, displacement capacity spectrum of SDOF system at each mode and step is determined based on the current frequency and current acceleration capacity spectrum. In this paper for both of the proposed and conventional methods, demand curve is obtained by time history analysis of a SDOF system and specifications of bilinear capacity spectrum. In the proposed method, determination of displacement for each point is based on NSP step that SDOF bilinear capacity curve intersect to demand curve. For evaluation of proposed and conventional methods a horizontally curved bridge have been selected and critical pier and earthquake corresponding to displacement capacity of bridge is determined through Incremental Dynamic Analysis(IDA). Then the proposed and conventional methods in the horizontally curved bridge are applied during NSP with force distribution based on first transverse mode shape. Assessing the result reveals that displacement from proposed and conventional method are different because of different formulations and dependency of proposed method to displacement vector,force vector and mass matrix of structures during NSP while the conventional method depends only to displacement of one point. Another feature that distinguishes proposed from conventional method and causes different results is the way that target displacement is determined from target spectrum displacement for top of critical pier. Finally comparison of top displacement of critical pier from proposed and conventional methods with those derived from (IDA) shows the efficiency of proposed method to reduce difference between the NSP and IDA results}, Keywords = {Control point,Displacement capacity spectrum,Target Displacement,Curved bridge}, volume = {14}, Number = {2}, pages = {117-128}, publisher = {Tarbiat Modares University}, title_fa = {توسعه روش طیف ظرفیت و تعیین تغییر مکان هدف بدون در نظرگیری نقطه کنترل در پل های دارای انحناء در پلان}, abstract_fa ={در تحلیل و طراحی پل ها تحت تأثیر نیروی جانبی بر اساس عملکرد برای ترسیم طیف ظرفیت و تعیین تغییر مکان هدف در روش متداول یک نقطه بر روی پل به عنوان نقطه کنترل باید مشخص شود و با انجام تحلیل استاتیکی غیر خطی فزاینده منحنی برش پایه در برابر جابه جایی نقطه کنترل ترسیم شده و سپس این منحنی به طیف ظرفیت تبدیل می شود . در خصوص تعیین محل نقطه کنترل، پیشنهادهایی به وسیله ی پژوهشگران ارائه شده است که می توان به راس پایه بحرانی و یا نقطه دارای تغییر مکان   بیشینه اشاره کرد که در تحلیل استاتیکی غیر خطی فزاینده محل نقطه دارای تغییر مکان بیشینه در تمام گام های تحلیل استاتیکی غیر   خطی فزاینده ثابت نبوده و می تواند تغییر کند پس انتخاب محل های مختلف به عنوان نقطه کنترل در پل ها در محاسبه طیف ظرفیت   پل در ناحیه غیرخطی تأثیرگذار است     . در این مقاله روش جدیدی برای ترسیم طیف ظرفیت تغییر مکان و تعیین تغییر مکان هدف بدون نیاز به نقطه کنترل در تحلیل استاتیکی غیرخطی فزاینده ارائه می شود     . در روش پیشنهادی، رسم طیف ظرفیت با استفاده از وضعیت لحظه ای کل سازه در هر گام از تحلیل استاتیکی غیر خطی فزاینده انجام شده و وضعیت گام به گام کل سازه در تعیین طیف   ظرفیت اثر گذار است     . با توجه به وابستگی ننایج تحلیل استاتیکی غیر خطی فزاینده به محل نقطه کنترل، ویژگی روش پیشنهادی عدم وابستگی به یک نقطه کنترل در تعیین طیف ظرفیت و تغییر مکان هدف است     . برای بررسی کارایی روش پیشنهادی در تعیین تغییر مکان هدف، یک پل دارای انحناء در پلان تحت اثر زلزله در جهت عرضی واقع شده و تغییر مکان بیشینه در راس پایه بحرانی   درتحلیل تاریخچه زمانی غیرخطی به دست آمده است     . سپس تحلیل استاتیکی غیر خطی فزاینده با استفاده از الگوی بار متناسب با شکل مود اصلی سازه در جهت ارتعاش عرضی بر روی سازه انجام گرفته و تغییر مکان هدف در راس پایه بحرانی با روش متداول   با تعیین نقطه کنترل و روش پیشنهادی بدون تعیین نقطه کنترل بدست آمده است     . مقایسه نتایج تغییر مکان هدف در راس پایه بحرانی نشان دهنده کارآیی روش پیشنهادی در کاهش اختلاف بین تغییر مکان راس پایه بحرانی از تحلیل استاتیکی غیر خطی   فزاینده نسبت به تحلیل تاریخچه زمانی غیر خطی است       .  }, keywords_fa = {نقطه کنترل,طیف ظرفیت تغییر مکان,تغییر مکان هدف,پل دارای انحناء در پلان}, url = {http://mcej.modares.ac.ir/article-16-9218-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9218-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Poorebrahimi, Gh.R.}, title = {Experimental and Numerical Modeling of Soft Soil Improvement using Compacted Lime Mortar Columns}, abstract ={Abstract: Construction of roads, railways and other engineering structures over soft soils usually involves consideration of excessive settlements, deformations, and stability problems. To avoid or reduce such problems, several ground improvement techniques are available including the use of column type elements. Stone columns represent the most known column-type techniques for improving soft soils. It is well established that the stone columns derive their load carrying capacity from the lateral confining pressure provided by surrounding soil. Since intermediate layers consisting of organic or very soft to soft soils can not provide proper lateral support to the stone columns, the external lateral support can be replaced in these columns by an internal bond between the stones. This can be done by applying binders such as lime during the installation of the stone/gravel columns, which bind the gravels together and form a solid column. An alternative method is suggested in the present study to improve the performance of stone columns in soft soils by using compacted lime mortar columns. Laboratory tests are carried out on large scale composite specimens composing of compacted lime mortar columns and soft clay surrounding it. Experiments were carried out on the both end bearing and floating columns with dimensions of 100 mm diameter, and 600 mm height. The columns were surrounded by soft soil in cylindrical tanks of 600 and 800 mm height, and a diameter varying from 230 to 320 mm to represent the required unit cell area of soft soil around each column assuming triangular pattern of installation of columns. In the field, the entire of the column treated ground will be subjected to loading from the superstructure. The same was simulated in the laboratory by loading the entire area of the specimen to study the stiffness of improved ground with regard to the influence of different parameters such as: area ratio (as the ratio of the area of the column (A S ) to the total area within the unit cell (A)), and shear strength of the clay. Finite element analyses have also been performed with   the software package PLAXIS V 8.2 using 15-noded triangular elements. Tests results show that   compacted lime mortar columns exhibit a stiffer and stronger response compared to conventional   stone columns installed in soft soils. These columns improve the load carrying capacity and decrease   the settlement of soft soils. The performance of these columns is significantly enhanced by increasing   the area ratio. However, when the area ratio exceeds 15%, the rate of increment of the load carrying   capacity is negligible. When the entire area of the composite specimens is loaded, because of the   confining effect of the boundary of the unit cell, failure does not take place even for settlement as high   as 15 mm. Comparison of numerical and experimental data shows a good agreement between the   results.    }, Keywords = {soft soils,stone columns,lime,load intensity,Settlement}, volume = {14}, Number = {2}, pages = {129-141}, publisher = {Tarbiat Modares University}, title_fa = {مدل سازی آزمایشگاهی و عددی اصلاح خاک های ریزدانه نرم با استفاده از ستون های شفته آهکی متراکم}, abstract_fa ={یکی از روشهای متداول و کارا برای اصلاح رفتار خاکهای مسالهدار، استفاده از ستونهای سنگی است . این ستون ها باعث افزایش ظرفیت باربری این نوع خاکها شده و نشست آنها را تحت بارهای وارده کاهش میدهند     . ستونهای سنگی ظرفیت باربری خود را به وسیله محصوریت ایجاد شده بهوسیله خاک اطراف بهدست میآورند     . در خاکهای ریزدانه بسیار نرم، فشار جانبی اعمالی به ستون کافی نبوده و ستونها تحت بارهای اعمالی دچار کمانش جانبی می شود     . یکی از روشهای جلوگیری از کمانش جانبی ستونها و ارتقاء عملکرد آنها در خاکهای بسیار نرم، استفاده از ستونهای سنگی صلب است     . در این مقاله نتایج یک مطالعه آزمایشگاهی و عددی که بهمنظور ارزیابی عملکرد ستونهای سنگی صلب از نوع شفته آهک متراکم برای اصلاح رفتار خاکهای   ریزدانه نرم انجام شده است، ارائه می شود     . در این پژوهش نمونههایی در ابعاد بزرگ متشکل از خاک رس و ستونهای شفتهآهکی متراکم با استفاده از تئوری سلول واحد در آزمایشگاه ساخته شده و با بررسی تأثیر پارامترهای مختلف، تحت بارگذاری قرار گرفته       -   استفاده شده است . نتایج آزمایشها نشان میدهد که ستون- V8.2 Plaxis اند. برای مدلسازی عددی نمونهها، از نرمافزار اجزاء محدود های شفتهآهکی متراکم بهمیزان قابل توجهی موجب افزایش ظرفیت باربری و کاهش نشست خاکهای ریزدانه نرم می شود و با   افزایش نسبت مساحت، تأثیر استفاده از این ستونها در بهبود رفتار خاک، مشهودتر میشود     . مقایسه نتایج آزمایشگاهی و نت ایج حاصل از مدلسازی عددی نشان میدهد که انطباق خوبی بین نتایج وجود داشته و میانگین اختلاف بین نتایج     6% است .  }, keywords_fa = {خاکهای نرم,ستونهای سنگی,آهک,شدت بار,نشست}, url = {http://mcej.modares.ac.ir/article-16-3725-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-3725-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Mamdoohi, A.R. and Saffarzadeh, M. and Shojaat, S.}, title = {A Stochastic Approach to Freeway Capacity Estimation: Tehran-Karaj Freeway Case Study}, abstract ={Capacity of a road facility as an important characteristic in transportation and traffic studies is defined as the maximum rate of flow that could be held by that facility, which has been supposed to have a constant and certain value. This assumption, although necessary for most traffic studies, has also caused some problems, like that of demand exceeding capacity in many road facilities. Researchers have recently shown that capacity is not necessarily the maximum flow rate held by a facility. They have also demonstrated that capacity has a stochastic nature rather than a constant and deterministic value. Stochastic approach to capacity is more complicated and comprehensive. In this approach, capacity is treated as a random variable generated from a population, and having corresponding distribution function. Knowing more about breakdown phenomenon, as transition from acceptable to unacceptable flow, plays a key role in this approach. To obtain breakdown flow rates, threshold speed as the quantitative measure is used to distinguish congested and non-congested flow rates. Flow rates occurring immediately before decrease of average speed below the threshold speed, are regarded as breakdown flow rates and their value in addition to non-congested flow rates are used to estimate the distribution function. Product Limit Method with analogy to life time data is used to estimate non-parametric function. The main advantage of this method is that it considers censoring data. In capacity estimation, if a time interval is followed by a breakdown, it will be regarded as uncensored interval; if it is non-congested it will be regarded as censored interval, meaning that capacity of the road is bigger than incoming demand. If it is located in a congested area, it would not be used in the estimation process. Two common parametric estimation methods are (OLS) ordinary least squares and (MLE) maximum likelihood estimation. Since binary data is used to estimate capacity distribution function, the ordinary least squares method is not useful with such data. Maximum likelihood estimation with a presumption about the type of distribution is used to estimate the parameters. Distribution function with the maximum log-likelihood value would be the function that has most likely produced the sample, and is known as the capacity of the freeway. In this paper, both non-parametric and parametric capacity distribution functions of Tehran-Karaj freeway as the oldest and the busiest freeway in Iran, serving and average of 100,000 passenger cars a day, are estimated. Threshold speed is found to be respectively 70 km/h and 75 km/h in two sections under investigation located in the direction to Karaj. Based on the data gathered for four months by traffic cameras; and refining to meet standard criteria, a sample of 229 and 169 breakdowns were detected at each section. Different distribution functions are fitted to the data, and with trial about different kinds of functions, Gumbel distribution is found to be the best distribution fitting the observed data.}, Keywords = {Freeway Capacity,Stochastic Approach,Maximum Likelihood Estimation,Product Limit Method,Distribution Function,Gumbel Distribution}, volume = {14}, Number = {2}, pages = {143-153}, publisher = {Tarbiat Modares University}, title_fa = {رویکرد تصادفی در تخمین ظرفیت آزادراه: موردپژوهی آزادراه تهران- کرج}, abstract_fa ={ظرفیت، به عنوان یکی از ویژگیهای اصلی بخش عرضه سیستم حمل و نقل، بیشترین نرخ جریانی است که تسه یلات قابلیت عبور آن را دارد و به شکل سنتی عددی ثابت فرض میشود . از جمله مشکلات این رویکرد بزرگتر ش دن حجم تردد از ظرفیت در بسیاری از تسهیلات است     . مطالعات اخیر نشان میدهند که ظرفیت تسهیلات، نهتنها بیشترین نرخ جریان تردد نیست ، بلکه ماهیتی تصادفی دارد     . رویکرد تصادفی به ظرفیت، با توجه به پیچیدگی بیشتر آن نسبت به رویکرد سنتی قطعی یا معین، نیاز به دادههای بیشتر و اطلاع از شکل تابع توزیع ظرفیت دارد که مبتنی بر مفهوم شکست در جریان ترافیک به عنوان گذار از شرایط   نامتراکم به شرایط متراکم و آستانه ظرفیت است     . مقاله جاری به تحلیل نظری رویکرد تصادفی در ظرفیت آزاد راه به عنوان حالت جامعتر، و کاربرد آن را در قالب موردپژوهی آزاد راه تهران     - کرج به عنوان قدیمیترین و پر رفت و آمدترین آزاد راه کشور با جا به جایی روزانه     90 تا 100 هزار وسیله نقلیه میپردازد. پس از تعیین نرخجریانهای شکست و نرخجریانهای روان، برای تخمین تابع توزیع ناپارامتری ظرفیت، از روش حد حاصلضربی و برای تخمین تابع توزیع پارامتری، از روش بیشینه درست نمایی با فرض تابع   توزیع ظرفیت استفاده میشود     . نتایج نشان میدهد که بر اساس اطلاعات چهار ماهه تردد در دو مقطع منتخب برای مورد پژوهی، تابع گامبل دارای بیشترین برازش از نظر لگاریتم احتمال است       .  }, keywords_fa = {}, url = {http://mcej.modares.ac.ir/article-16-791-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-791-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Tasnimi, A.A. and Kazemi, H.R.}, title = {Nonlinear Seismic Analyses of Median Ductile RCMRF Structures Based on Variation of Columns Acceptance Criteria}, abstract ={Based on experimental evidence and empirical models the proposed supplement to ASCE 41- 06 is developed for the purpose of updating provisions related to existing reinforced concrete structural buildings. Several experimental research programs have demonstrated that many older-type columns are capable of sustaining limited plastic deformation due to flexural yielding prior to shear failure. This proposed supplement concentrates on this failure mode and includes the categorization of columns based on failure mode, the selection of target probabilities of failure for each failure mode and revisions to modeling parameters and acceptance criteria for reinforced concrete columns. In this research, the effect of new provisions on seismic evaluation of reinforced concrete moment resisting frame is investigated. In this regard three medium ductile MRCRF structures with 4, 8 and 12 stories and two direction median moment resisting frame systems are considered. These structures initially have been analyzed and designed according to ‘Iranian Standard 2800, for seismic design of buildings’ and ‘Iranian concrete code of practice’. Then nonlinear static analysis and nonlinear time history analysis methods have been utilized to evaluate the seismic performance of these structures. In nonlinear static analysis there are several methods for determining target displacement among them some reliable methods are displacement coefficient method (FEMA-356), Capacity spectrum method (ATC-40), and equivalent linearization method and modifies coefficient method (FEMA-440). The target displacements with these methods are compared with maximum displacement in nonlinear time history analysis. It is observed that capacity spectrum method given by ATC-40 reports target displacement values higher than time history analysis. Furthermore, results obtained from the equivalent method and the modified coefficient methods suggested by FEMA-440 are closer to time history analysis values. The performance levels of these structures have been evaluated based upon target displacement of nonlinear static analysis that obtained from FEMA-440 methods and maximum displacement in nonlinear time history analysis. The effect of the variation of reinforced concrete columns modeling parameters and acceptance criteria on performance levels of reinforced concrete structure is investigated. For this purpose in nonlinear seismic design, the modeling parameters and acceptance criteria have been considered with those from FEMA-356 for columns “controlled by flexure” and then with those from proposed supplement to ASCE 41-06 for flexure failure (flexural yielding without shear failure) and flexure-shear failure (shear failure following flexural yielding). The obtained results indicate that these structures are to some extant conservative in their seismic performance due to the modifications of ASCE41-06.}, Keywords = {performance base design,Nonlinear analysis,modeling parameters,Acceptance criteria,reinforced concrete columns}, volume = {14}, Number = {2}, pages = {155-164}, publisher = {Tarbiat Modares University}, title_fa = {تحلیل غیرخطی– لرزه ای قاب های خمشی متوسط بتن مسلح با توجه به تغییر درمعیارهای پذیرش ستون ها}, abstract_fa ={بر اساس گزارش های علمی - تحقیقاتی، به تازگی بازبینی استاندارهای مربوط به طراحی بر اساس عملکرد و بهسازی پارامترهای مدلسازی و     ASCE41- لرزهای ساختمانهای موجود، مورد توجه قرار گرفته است. در این راستا برای تکمیل استاندارد 06   معیارهای پذیرش اجزای سازههای بتن مسلح بر مبنای دادههای آزمایشگاهی و مدلهای تجربی بازنگری شده است . این اصلاحیه با تمرکز به مود شکست خمشی     - برشی ستونهای بتن مسلح، پارامترهای مؤثر در مدلسازی و معیارهای پذیرش آنها را بررسی کرده است     . این مقاله، تأثیر تغییرات اعمال شده را بر روی عملکرد لرزهای سازههای بتن مسلح که بر اساس ویرایش سوم استاندارد 2800   و آییننامه بتن ایران تحلیل و طراحی شدهاند، ارزیابی کرده است . سازههای مورد مطالعه سه قاب خمشی متوسط و منظم سه بعدی   8 و 12 بود که با استفاده از روش استاتیکی غیرخطی و تاریخچه زمانی تحلیل شدهاند. تغییر مکان هدف در تحلیل ، با تعداد طبقات 4   روش طیف ، FEMA- استاتیکی غیرخطی تحت الگوهای بارگذاری متفاوت، با روشهای مختلف مانند روش ضرایب تغییرمکان 356   به دست آمده و با تغییرمکان ماکزیمم تحلیل FEMA- روش خطی سازی معادل و روش ضرایب اصلاح شده 440 ،ATC- ظرفیت 40   همخوانی بیشتری با نتایج FEMA- تاریخچه زمانی غیرخطی مقایسه شده است. برای سازههای مورد مطالعه نتایج روشهای 440   تحلیل تاریخچه زمانی دارند . سطوح عملکردی سازهها در تغییرمکان هدف تحلیل استاتیکی غیرخطی و تغییرمکان ماکزیمم تحلیل تاریخچه زمانی ارزیابی شده است     . نتایج به دست آمده از تحلیلهای غیرخطی حاکی از آن است که اعمال تغییرات مذکور در موجب تغییر چشمگیر در سطوح عملکردی سازهها میشود       .  }, keywords_fa = {تحلیل غیرخطی,طراحی بر اساس عملکرد,پارامترهای مدلسازی,معیارهای پذیرش,ستونهای بتن مسلح}, url = {http://mcej.modares.ac.ir/article-16-1685-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1685-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Dehghani, A.A. and AbdiDehkordi, M.}, title = {Application of genetic algorithms in the optimization of empirical relations to estimate of geometrical characteristics of the scour hole downstream of grade control structures}, abstract ={Grade-control structures are aimed at preventing excessive channel-bed degradation in alluvial channels and at the outlet of a grassed waterway to stabilize the waterway outlet. The erosive action of the weir overflow may, however, cause significant local scour downstream and may endanger the stability of these structures. The scour process can be split up into different time phases. In the beginning the development of scour is very fast, and eventually an equilibrium situation is reached depending on clear water or live bed flow condition. Appropriate design of grade-control structures requires estimate geometric characteristics of the downstream scour. The local scour downstream of a grade-control structure located on an alluvial bed is a very complex and dynamic phenomenon which is influenced by many parameters. Most of these parameters are related to each other and determination of them is difficult. The estimation of maximum scour depth is very important in planning, design and management of hydraulic structures. Therefore, there is a great need to develop good prediction methods for geometric characteristics of scour hole downstream of grade control structures. Some of researchers studied scour downstream of grade-control structures and presented different empirical equations for estimation of maximum scour depth based on experimental data. The results of literatures show that the equation of D'Agostino and Ferro (2004) can be used as one of the most important empirical equations to estimate the maximum scour depth. In this study, coefficients of D'Agostino and Ferro (2004) equation to estimate of the maximum scour depth, horizontal distance between the weir crest and the maximum scour depth position, horizontal distance between the weir crest and sand deposition and maximum height of sediment deposition, were optimized by applying genetic algorithm. For this purpose, the field and laboratory data of Veronese (1937), Bormann and Julien (1991), D’Agostino(1994), Mossa (1998), Lenzi et al. (2000), Missiaga stream (2004), Falciai and Giacomin (1978), Some large-scale data ((Veronese 1937), Scimemi (1939), Whittaker and Schleiss (1984)) and shahabi (2010) were used for training and validation of the equations. The efficiency and accuracy of each equations were examined based on statistical Analyses such as percent error, root mean square error, mean bias error and correlation coefficient using independent data sets of training data and were compared with the results obtained from the equations proposed by D'Agostino and Ferro (2004). The results show that the value of percent error, root mean square error, mean bias error and correlation coefficient for maximum scour depth, horizontal distance between the weir crest and the maximum scour depth position, horizontal distance between the weir crest and sand deposition and maximum height of sediment deposition were 46.09, 11.78, 10.28 and 118.05, respectively. The corresponding values are 128.1, 27.73, 15.23 and 194.46 by using D'Agostino and Ferro relation. The results showed that the root mean square error and mean bias error are decreased by using proposed equations and the accuracy of obtained results by presented equations is higher than D'Agostino and Ferro (2004) equations. So it is recommended to use the proposed relations for assessing the characteristics of scour hole downstream of grade control structures.}, Keywords = {Scouring,Control structures,Experimental studies,Field studies,Genetic algorithm}, volume = {14}, Number = {2}, pages = {165-173}, publisher = {Tarbiat Modares University}, title_fa = {کاربرد روش جستجوی ژنتیکی در بهینه سازی روابط تجربی تخمین مشخصه های هندسی حفره ی آبشستگی پائین دست سازه های تثبیت کننده ی بستر}, abstract_fa ={بخش مهمی از مطالعات صحرایی به بررسی بیشینه عمق آبشستگی پاییندست سازههای کنترلی و تثبیت کنندهی بستر مانند سریز، آببند و غیره میپردازند؛ همچنین برخی از پژوهشگران روابط تجربی متعددی را بهمنظور برآورد بیشینه عمق آبشستگی در شرایط هیدرولیکی معین ارائه کردند . در این مطالعه ضرایب روابط تجربی ارائه شده به وسیله ی داگوستینو و فروو ( 2004 ) برای بررسی خصوصیات بستر پاییندست سازههای کنترلی و تثبیت کنندهی بستر، با استفاده از روش جستجوی ژنتیکی بهینه شده است       .   به این منظور از مجموعه دادههای آزمایشگاهی و صحرایی جمعآوری شده به وسیله ی سایر پژوهشگران برای آموزش این معادلات و سنجش میزان دقت و کارایی آنها استفاده شد؛ این مجموعه دادهها در مقیاسهای متفاوت اندازهگیری شده و دارای توزیع دانه   -   بندی اندازهی ذرات متفاوت است . دقت هر یک از روابط بهینه شده با کاربرد شاخصهای آماری مختلف، با روابط ارائه شده توسط داگوستینو و فروو     ( 2004 ) مقایسه شد. نتایج نشان میدهد مقادیر شاخصهای آماری درصد خطا، ریشهی میانگین مربعات خطا و میانگین خطای اریبی در روابط بهینه شده به میزان قابل توجهی کاهش یافته است؛ پس روابط بهینه شده به وسیله ی روش جستجوی   ژنتیکی نسبت به روابط تجربی موجود از دقت و کارایی بیشتری در تخمین مشخصههای هندسی حفرهی آبشستگی پایین دست   سازههای کنترلی و تثبیت کنندهی بستر برخوردار است       .  }, keywords_fa = {بیشینه عمق آبشستگی,سازههای کنترلی و تثبیت کنندهی بستر,روش جستجوی ژنتیکی}, url = {http://mcej.modares.ac.ir/article-16-7436-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7436-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Zarparvar, P. and Safi, M.}, title = {Estimation of the Pattern of Debris Load Caused By an Earthquake on Steel Beams}, abstract ={During an earthquake and its effect, what happens on buildings is local damage and destruction which is different due to different characteristics such as diverse earthquake and geotechnical characteristic, different methods of analysis for earthquake-resistant structures, etc. Therefore, in addition to removing structural elements and their falling as debris, a shock and impulsive load could be added to the dynamic load imposed by the earthquake. Impact loads with extreme severity are loads with very low frequency of occurrence, but with extraordinary consequences. Undoubtedly appearing greater success in designing buildings resistant against extraordinary loads is required to forecast the real pattern and the impact of the impulsive loads. In other words, identify all possible failure modes of structures under extraordinary loads is necessary, which requires nonlinear analysis of structures under various loading conditions. Detailed modeling of the impact of an upper floor onto the floor below is feasible using current sophisticated nonlinear dynamic analysis software. Yet the computational effort in the case of large and complex structural systems can be excessive, especially if a detailed model of the whole structure is considered. Moreover, such analysis requires structural engineers with considerable expertise in nonlinear structural dynamics. Due to these limitations, detailed impact modeling is not practical for design applications. Hence, there is an evident need for simple, yet sufficiently accurate methodologies that can be used to establish whether the strength, ductility supply and energy absorption capacity of the lower impacted floor are adequate to withstand the imposed dynamic loads from the falling floor(s). This paper proposes a new design methodology for progressive collapse assessment of floor within multi-storey buildings subjected to impact from an above failed floor. The amount of debris and its scattering and distribution on different floors of a building play an important role in the operation of the impact load. The important point is that how these parameters should be considered in the dynamic analysis and how much the structure’s respond is sensitive to the impact characteristics such as impact velocity, the mass of debris and its distribution. This study has attempted to calculate the dynamic load factor (DLF) for samples of steel beams with an elastic-plastic behavior, and to extract the pattern of debris impact load in order to provide an equivalent loading pattern to estimate the performance of structures subjected to above failed floor(s). The study of dynamic load factors for the samples illustrates that the period of beam, the height of falling and the mass of debris have a noticeable effect on the result so that the DLF decreases by increasing in amount of the period of beams or the mass of debris, as well as it increases by increasing the height of falling. About the achieved patters for the impact load what is important is providing multi-line graphs in order to estimate the dynamic effect of the debris impact}, Keywords = {Impact load,Debris load,Dynamic load factor,progressive collapse}, volume = {14}, Number = {2}, pages = {175-186}, publisher = {Tarbiat Modares University}, title_fa = {تخمین الگوی بار ناشی از ریزش آوار زلزله بر تیرهای فولادی}, abstract_fa ={آنچه که در طول یک زلزله و اثر آن بر روی ساختمانها رخ می دهد آسیب و تخریب موضعی ساختمان می باشد . در این شرایط سازه در حین وقوع زلزله و در طی لحظاتی، تحت یک بار شوک و ضربه ناشی از آوار و خرابی اجزاء سازه قرار گرفته و   علاوه بر حذف اجزا و المان هایی از سازه بار دینامیکی ناشی از زلزله با آوار ترکیب شده و بار افزایش یافته جدیدی را ایجاد می   کند     . مدلسازی ضربه کف طبقات بالایی به طبقه پایین تر با استفاده از برنامه های کامپیوتری حرفه ای امروزی که قادر به انجام تحلیل دینامیکی غیر خطی می باشند امکان پذیر می باشد     . اما حجم کاری مدلسازی کامپیوتری بویژه اگر سازه بزرگ و پیچیده باشد و تمام جزئیات نیز در نظر گرفته شوند، بسیار زیاد می شود     . در این تحقیق سعی شده است که با محاسبه ی ضریب بار دینامیکی برای نمونه ای از تیرهای فولادی     (در دو ناحیه الاستیک و پلاستیک) به استخراج الگوی بار ضربه ی آوار تحت شرایط مختلف و درنتیجه ارایه ی یک الگوی بار گذاری معادل به منظور تخمین رفتار سازه در مقابل ریزش طبقات فوقانی گام برداشت     . در طول تحقیق مشخص می شود که پارامترهایی نظیر زمان تناوب تیر، ارتفاع سقوط و جرم آوار اثر بسزایی بر نتایج بدست آمده دارند؛   بطوریکه با افزایش زمان تناوب و جرم آوار مقدار ضریب بار دینامیکی کاهش و با افزایش ارتفاع سقوط این مقدار افزایش می یابد       .  }, keywords_fa = {بار ضربه,بار آوار,ضریب بار دینامیکی,الگوی بار ضربه}, url = {http://mcej.modares.ac.ir/article-16-7109-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7109-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {vaseghi, ل and tamjid, f}, title = {Evaluation of Seismic Performance of Reinforced Concrete Frames Using Pall Friction Damper}, abstract ={Abstract: Considering the seismicity of most of the areas in Iran, it is inevitable to confront the earthquake because of its major property and life damages. Therefore researchers put a great effort on designing and strengthening against earthquake. The researches conducted so far for improving the reinforced concrete structures using different types of steel braces and analytical studies and widespread experiments has been done for confronting destructive effects of earthquake on structures, results show the proper effectiveness of different mechanisms of inactive seismic control of structures as an efficient option for confronting the earthquake forces. Of different control methods, using friction damper could be counted as one of the best methods for improving the seismic behavior of current structures, as it uses a simple mechanism and doesn’t need specific materials or technology. By using friction dampers both the rigidity and the structure’s hysteresis energy loss ability is increased. These dampers by their inelastic behavior in different points of the structure cause the loss of incoming energy of earthquake. Also in high importance structures, by selecting the proper design parameters, it is possible to prevent the main structural members to enter the inelastic behavior limit which causes local damages to some parts of them or minimize that. This system was first introduced by Pall and March in 1982. The mechanism of this system is creating slippage friction surfaces at the intersection of braces. For building frames, these dampers could be used in crossed tension bracing, single diagonal bracing and Chevron bracing. The first model of pall friction damper was tested in chevron bracing against earthquake in Eaton Building in Canada. The purpose of this study is to investigate the role of Pall friction dampers in reducing structural response during the earthquake. Therefore, modeling of the damper is based on the model used by the Pall Corporation in Eaton Building. The functioning of this damper is by generating friction under lateral shear force which causes the movement of the damper and generation of slippage in it. Therefore, three concrete moment frames with 5, 8 and 10 stories, have been designed according to the Iranian National Codes. Using SAP2000, v14, several static nonlinear analyses were done to get the performance point of frames on the basis of the capacity spectrum method. Adding chevron braces to the mid span, the target displacement of frames were determined. Considering the fact that none of the braced moment frames satisfied the Life Safety criteria under Design Based Earthquake, Pall friction dampers have been added to the frames and static nonlinear analysis were done by several slip loads such as 1%, 10%, 25%, 50%, 75% and 100% of frame weights. Evaluation showed that in optimum slip Load, the performance level of the frames improves.}, Keywords = {Seismic Retrofitting,Performance level,Static Nonlinear Analysis,Dynamic Nonlinear Analysis,Friction Damper}, volume = {14}, Number = {2}, pages = {187-203}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی عملکرد لرزه ای سازه های بتنی با بکارگیری میراگر اصطکاکی پال}, abstract_fa ={هدف این پژوهش، بررسی نقش میراگرهای اصطکاکی پال در کاهش پاسخ سازه در مقابل زلزله است . به این منظور سه   8 و 10 طبقه، بر اساس آیین نامه های ایران به صورت قاب خمشی بتن مسلح با شکل پذیری متوسط طراحی شده اند . ، قاب بتنی 5   نسخه 14 بر روی آن صورت گرفت تا نقطه عملکرد سازه بر اساس SAP سپس آنالیز استاتیکی غیرخطی با استفاده از نرم افزار 2000   روش طیف ظرفیت به دست آید، و قاب ها با افزودن مهار بندهای زوج ناودانی در دهانه وسط تقویت شده و تحت آنالیز پوش آور قرار گرفتند . با محاسبه ی سطح عملکرد و عدم ارضای شرط حفظ ایمنی جانی ساکنین در هنگام زلزله سطح خطر- 1 ،قاب خمشی   75 % و 100 % وزن ،%50 ،%25 ،%10 ،% بتن مسلح و مهاربند هم محور آن، به میراگر اصطکاکی مجهز شدند و با بار های لغزش 1   ساختمان، تحت آنالیز پوش آور قرار گرفتند و سطح عملکرد آنها ارزیابی شد . ارزیابی ها نشان داد که بار لغزش بهینه برای میراگرها به تعداد طبقات ساختمان بستگی دارد و در بار لغزش بهینه سطح عملکرد سازه بهبود پیدا می کند       .  }, keywords_fa = {بهسازی لرزه ای,سطح عملکرد,تحلیل استاتیکی غیر خطی,تحلیل دینامیکی غیر خطی,میراگر اصطکاکی}, url = {http://mcej.modares.ac.ir/article-16-5696-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-5696-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Arianfar, Ali and Ahmadi, Mortez}, title = {Assessment of AE and DRA Methods for In-situ Stress Measuring and Study of Delay Time in both Methods}, abstract ={There are several direct and indirect methods to estimate in-situ stress. Generally in all methods rock breaking is required for in-situ stress determination in which broken rock response is due to displacement/strain or hydraulic pressure. Hydraulic fracture, Relief method, Jacking method, Strain Recovery method and borehole breakout method are known as direct methods. On other hand, the indirect methods estimation is based on changing of some physical or other properties of rock which represent from applying stress. Even though, these methods are also laboratory methods, however, indirect techniques are non destructive, low cost and simple for estimation of in-situ stress. This is the reason which has motivated rock mechanics researchers to use Acoustic Emission (AE) and Deformation Rate Analysis (DRA) methods. Results aaccuracy of the methods are affected by rock texture, cracks type and delay time. The delay time means that time between coring in field and test time for stress measuring. The capability of AE and DRA methods in stress estimation have been assessed in this research and the effect of delay time on estimated stress are worked out. AE and DRA tests were carried out on the samples for estimation of in-situ stress. Stress has a nature tensor with 9 components, in which six of them are independent components and the rest (3 components) are dependent components. Each component of tensor need to be determined with a total of six tensors which required six tests in six different orientations. Six series of samples with different delay times (4 series with 20 days as delay time and 2 series with 5 years as delay time) were obtained from abutments of Seyamreh dam (South-West of Iran). AE and DRA tests were carried out. The values obtain from these AE and DRA tests were compared with result of Hydraulic Fracturing (HF) method which carried out at the same locations. The comparison shows a good conformity between the result of AE and DRA methods with those of HF method for horizontal stresses where as there are variations noticed for vertical stress values. This may be due to this fact that in the HF method assumes the vertical stress is equal to overburden weight which is not correct assumption. The other result of this assumption is that the others two principal stresses are horizontal. It is obvious if one of principal stresses would be vertical the two other have to be horizontal. Furthermore, this investigation infers that delay time is very important parameter on the results obtained by AE & DRA methods. Thus better accuracy can be computed when the delay time is minimized.}, Keywords = {Acoustic emission,Deformation Rate Analysis,Stress Measurement,Delay Time}, volume = {14}, Number = {5}, pages = {1-9}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی روش AE و DRA در اندازه گیری تنش برجا و بررسی اثر زمان تاخیر در این دو روش}, abstract_fa ={ تخمین تنش برجا به روش آزمایشگاهی به خاطر هزینه کم و سریع بودن، امروزه مورد توجه پژوهشگران مکانیک سنگ قرار گرفته­است. از روش‌های آزمایشگاهی تخمین تنش برجا که پژوهش روی آن افزایش یافته است، روش انتشار اکوستیک(Acoustic Emission) و آنالیز نرخ تغییر شکل(Deformation Rate Analysis) است. دقت نتایج در این روش­ها برگرفته از بافت سنگ، نوع ترک‌ها و اثر زمان تاخیر است. در این پژوهش توانایی روش AE و DRA در تخمین تنش برجا و اثر زمان تاخیر در مقدار تنش اندازه­گیری شده و بررسی شده است. زمان تاخیر فاصله زمانی بین کرگیری از محل و زمان آزمایش است. برای اندازه­گیری تنش برجا از تکیه­گاه سد سیمره، 6 سری نمونه با زمان تاخیرهای متفاوت (دو سری نمونه با زمان تأخیر 5 سال و چهار سری نمونه با زمان تاخیر 20 روز)  تهیه و آزمایش روی آنها انجام شد. مقدار تنش تخمین زده شده از روش­های AE و DRA محاسبه و با نتایج روش شکست هیدرولیکی (Hydroulic Fracturing) مقایسه شد. نتایج حاکی از هم‌خوانی خوب بین روش AE و DRA با روش شکست هیدرولیکی است. تنها اختلاف در مقدار تنش قائم بوده که علت این امر این است که در روش HF فرض برابری تنش قائم اصلی معادل با وزن روباره است. نتایج نشان می­دهند که زمان تاخیر باعث پراکندگی نتایج در دو روش AE و DRA شده و برای حصول نتیجه بهتر در مقدار اندازه­گیری شده زمان تاخیر باید کمینه ممکن باشد.}, keywords_fa = {انتشار آوایی,آنالیز نرخ تغییر شکل,تنش سنجی,زمان تأخیر}, url = {http://mcej.modares.ac.ir/article-16-2877-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2877-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Emami, Mohammad and Yasrebi, S.Shahabodi}, title = {Application of artificial neural networks in interpretation of pressuremeter test results}, abstract ={In-situ tests play important role in any geotechnical investigation. Pressuremeter test can be considered one of the most important in situ tests.This test can be considered one of the most important in situ tests in Geotechnical Engineering. This test is capable to properly estimate deflection parameters of soil. Three types of pressuremeters exist based on their placement in the boreholes: Predrilled pressuremeters (P.D.P), Self-boring pressuremeters (S.B.P) and Push-in pressuremeters (P.I.P). The Predrilled pressuremeters (P.D.P) have been used in this project. Based on expansion of a cylinder that is placed inside the borehole the pressure-volume variation during testing is recorded. In this research, the results of approximately 500 conducted Pressuremeter tests on the soils by Pajohesh Omran Rahvar Ltd (2006-2007) are employed. The number of tests decreased to 400 due to lack of accuracy and also high changes in the range of Pressuremeter modules. The tests have been carried out on the soils of Northwest Iran (Tabriz), South Iran (Kharg Island) and Northeast Iran (Mashhad). The Pressuremeter instrument used is menard pre-boring. Conducted tests in accordance with ASTM-D4719 represented acceptable accuracy.  In the current paper, three types of Artificial Neural Network (ANN) are employed in interpretation of pressuremeter test results. First, multi layer perceptron neural network, one of the most applicable neural networks, is used. Then, neuro-fuzzy network, combination of neural-phase network is employed and finally radial basis function, a successful network in solving nonlinear problems, is applied. Neural network models showed prosperity to interpret Pressuremeter test. Soil physical and compaction properties are used in all these models. The applied models own 5 input parameters and 1 output parameters. Hidden layers with different number of neurons are tested in both one and two layers networks so as to select the most proper network architecture. It has been shown that a three-layer perceptron with differential transfer functions and sufficient number of neurons in hidden layer can approximate any nonlinear relationship. Consequently, one hidden layer is used in the present study. The neural network toolbox of MATLAB7.4, a popular numerical computation and visualization software, is used for training and testing of the MLPs. Transfer functions of networks are selected by trial and error.  A large complex of carried out tests on the extensive range of fine and course grained soils is used as database. In order to determine the most exact network in the perceptron neural network, some networks with different architecture are employed. Of all neural network models, multi-layer perceptron neural network proved to be the most effective. However, other applied networks have shown favorable performance. Finally, different models have been compared and network with the most outstanding performance is determined. In order to evaluate the capability of model generalization, the performance of mentioned network against inexperienced data has been compared with empirical results. Contrary to conventional behavioral models, models based neural network do not demonstrate the effect of input parameters on output parameters. This research is response to this need through conducting sensitivity analysis on the optimal structure of proposed models. Also, derivation of governing equation for neural network model give more assurance to user to employ such models and consequently this facilitates the application of models in the engineering practices.}, Keywords = {IKey words: Interpretation,Pressuremeter test,Artificial Neural Network,Multi-layer perceptron,Neurofuzzy,Radial Basis Function,Sensitivity analysis}, volume = {14}, Number = {5}, pages = {11-25}, publisher = {Tarbiat Modares University}, title_fa = {کاربرد شبکه عصبی مصنوعی در تفسیر نتایج آزمایش پرسیومتری}, abstract_fa ={آزمایش پرسیومتری، یکی از مهم­ترین آزمایش‌های برجای مهندسی ژئوتکنیک است. در این مقاله از سه نوع شبکه عصبی مصنوعی (ANN) به منظور تفسیر نتایج آزمایش پرسیومتری استفاده شده است. در ابتدا از شبکه عصبی چند لایه پرسپترون، در ادامه از شبکه نروفازی بهره گرفته شده و در پایان از شبکه عصبی تابع مبنای شعاعی استفاده شده است. مدل‌ها از ساختار کلی دارای 5 ورودی و یک خروجی تشکیل شده­اند. در پایان مدل‌های مختلف شبکه­های عصبی با یکدیگر مقایسه شده و شبکه­ای که بهترین عملکرد را داشته مشخص شده است. برای ارزیابی قدرت تعمیم مدل، عملکرد شبکه مورد نظر در مقابل داده­های تجربه نشده با نتایج تجربی مورد مقایسه قرار گرفت. مدل‌های مبتنی بر شبکه­های عصبی توضیحی در مورد چگونگی اثر پارامترهای ورودی بر خروجی نمی­دهند. در این پژوهش با انجام آنالیز حساسیت برروی ساختار بهینه مدل معرفی شده سعی شده است تا حدودی به این سوال پاسخ داده شود.}, keywords_fa = {تفسیر آزمایش پرسیومتری,شبکه عصبی مصنوعی,چند لایه پرسپترون,نروفازی,تابع مبنای شعاعی,آنالیز حساسیت تفسیر آزمایش پرسیومتری,آنالیز حساسیت}, url = {http://mcej.modares.ac.ir/article-16-5107-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-5107-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {1, 1}, title = {Determination of Bearing Capacity for Driven Piles in Sandy Soils by Using Artificial Neural Network Method}, abstract ={Determining the bearing capacity of piles is an important issue that always Geotechnical engineers focus on. Effect of factors such as environmental dissonance of soil which contains a pile, pile implementation, pile gender and its shape make correct estimation of bearing capacity difficult. Pile load testing as a reliable method could be used in various stages of analysis, design and implementation of piles to determine theaxial bearing capacity of piles. On the other hand, pile load testing, despite high accuracy, imposes high cost and long duration for development projects and it causes limitations in this experiment. Thus acceptance of numerical analysis at geotechnical studies is increasing. The modeling using artificial neural networks is the method that is based on previous data and don’t need to simplify and improve the high reliability coefficient. In this study serious models of multi-layer perceptron neural network, one of the most commonly used neural networks, was used. Network design and factors influencing its behavior in this issue has been studied as a summary. In this study, artificial neural networks are used for prediction of bearing capacity of driven steel piles in sandy soil, in all models four parameters are used as input data which are length and diameter of the pile, the coefficient of elasticity and internal friction angle of soil and the bearing capacity of piles is used as output data. Models have reasonable success in predicting the bearing capacity of piles. In order to evaluation of networks, the different indices such as RMSE, MAE, MAXAE and SDAE were used. To increase the accuracy of predicting bearing capacity, for the network training stage the real tests that has been done at the geotechnical studies of dry dock area hormozgan by POR Consulting Engineers were used.Acording to (Because we) need of more data for training and testing network, several tests on pile bearing capacity, in smaller dimensions were performed in the laboratory. The sixty tests have been performed on piles with various length (35, 40, 45 and 50 cm), various diameters (20, 25 and 32 mm) and different relative compacted sandy beds (50, 60, 70, 75 and 80%). To perform these tests the device of pile bearing capacity, made in university of TarbiatModarres, was used. Models based on neural networks, unlike traditional models of behavior don’t explain effect of input parameters on output parameters. In this study, by the sensitivity analysis on the optimal structure of introduced models in each stage it has been somewhat trying to response this question. .}, Keywords = {pile load testing,device of determining pile bearing capacity,artificial neural networks,Multi-layer perceptron,Sensitivity analysis}, volume = {14}, Number = {5}, pages = {27-36}, publisher = {Tarbiat Modares University}, title_fa = {تعیین ظرفیت باربری شمع‌های کوبشی در خاک‌های ماسه‌ای با استفاده از شبکه‌های عصبی مصنوعی}, abstract_fa ={ اثر عواملی نظیر ناهمسانی محیط خاک در برگیرنده یک شمع، اجرای شمع، جنس شمع و شکل آن، تخمین صحیح ظرفیت باربری یک شمع را با مشکل همراه می­سازد. با آن که آزمایش بارگذاری شمع می­تواند با وجود دقت بالا، به عنوان یک روش قابل اعتماد در مراحل مختلف تحلیل و طراحی به کار رود، هزینه های زیاد و زمان انجام طولانی را برای پروژه­های عمرانی تحمیل می­کند و همین مساله باعث ایجاد محدودیت­هایی در انجام این آزمایش می­شود. در این میان مدل‌سازی با استفاده از شبکه­های عصبی مصنوعی روشی است که بر اساس داده­ها و اطلاعات قبلی بوده و نیازی به ساده‌سازی و استفاده از ضرایب اطمینان بالا ندارد. در این مقاله، شبکه­های عصبی مصنوعی برای پیش­بینی ظرفیت باربری شمع­های فلزی ته باز کوبیده شده در خاک­های ماسه­ای، به کار گرفته شده­اند. از 4 پارامتر طول شمع، قطر شمع، مدول الاستیسیته خاک و زاویه اصطکاک داخلی آن به عنوان ورودی و از ظرفیت باربری شمع به عنوان خروجی استفاده شده است. چگونگی طراحی شبکه و عوامل موثر بر رفتار آن در مسئله مربوطه به صورت خلاصه بررسی شده است. در پایان با آنالیز حساسیت بر روی ساختار بهینه مدل‌های معرفی شده، در خصوص چگونگی اثر 4 پارامتر ورودی بر خروجی شبکه بحث شده است. .}, keywords_fa = {آزمایش بارگذاری شمع,دستگاه تعیین ظرفیت باربری,شبکه‌های عصبی مصنوعی,چند لایه پرسپترون,آنالیز حساسیت}, url = {http://mcej.modares.ac.ir/article-16-9187-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9187-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Jafari, Fatemeh and SalehiNeyshabouri, S. Ali Akbar}, title = {Numerical Study of Performance of Baffle Blocks in Submerged Hydraulic Jumps}, abstract ={Hydraulic jumps occur in natural systems like streams and rivers as well as manufactured systems. Samples of the latter occurance are jumps in water distribution and irrigation networks formed downstream of hydraulic structures such as spillways, sluice gates, and drops. These structures are usually designed for a specific tailwater depth. Stilling basins with baffle blocks are frequently used as energy dissipators downstream of hydraulic structures. Baffle blocks are often used to stabilize the jump, decrease its length and increase the energy dissipation. If the flow rates become more than the design discharge, the tail water depth will be greater than the one required for a free jump. These situations are common in low head hydraulic structures including low diversion dam spillways and gates. Under such conditions the hydraulic jump will be submerged.  The performance of the blocks in submerged jump (SJ) condition differs from the free jump (FJ) case. According to some factors such as Froude number, block shape and location and submergence factor, flow regimes on baffle blocks in condition of submerged hydraulic jumps which occurs in stilling basins, are classified into two regimes, the deflected surface jet (DSJ) and reattaching wall jet (RWJ). In this article a numerical study was conducted to investigate flow pattern, vortexes and the magnitude of vorticity in submerged hydraulic jumps with baffle blocks downstream of a sluice gate. The results were compared to ones in same conditions without blocks. 3D RANS simulations have been applied by Fluent software. RSM turbulence model were used which illustrated much precise results in verification. Three numerical models have been created; Submerged wall jet without blocks, submerged hydraulic jumps with baffle blocks in the condition of deflected surface jet flow regime and submerged hydraulic jumps with baffle blocks in the condition of reattaching wall jet flow regime. Flow pattern has been exhibited for each model and results were compared with each other. Vortexes formed in such situations classified into three groups according to axis which they whirl around. It was observed that deflected surface jet regime has more vortexes in comparison to the two other conditions. In addition, by measuring the average magnitude of vorticity in cross-sections it has been concluded that z-vortexes –vortexes which rotate around z axis– much more powerful than x- and y-vortexes as they determine the kind of flow regime. Furthermore, this magnitude is about two times larger in deflected surface regime than two other situations. This fact leads to more turbulence in the flow that makes deflected  surface jet  regime the desirable condition in which baffle blocks perform more efficiently as energy dissipators in comparison to two other investigated models. In order that, from energy vantage point, conditions should be provided in a way to form submerged hydraulic jump as deflected surface jet regime.}, Keywords = {Energy Dissipation,submerged hydraulic jumps,baffle blocks,numerical simulations,Stilling basin}, volume = {14}, Number = {5}, pages = {37-47}, publisher = {Tarbiat Modares University}, title_fa = {بررسی تأثیر بلوک های میانی حوضچه آرامش در حالت پرش هیدرولیکی مستغرق بر الگوی جریان}, abstract_fa ={در این مقاله به بررسی عددی گردابه های به وجود آمده و مقدار چرخش در پرش هیدرولیکی مستغرق شکل گرفته در حوضچه آرامش بدون و با بلوک های میانی پرداخته شده است. پرش هیدرولیکی مستغرق تحت تاثیر بلوک های میانی حوضچه آرامش، تنها به صورت دو نوع رژیم اتفاق می­افتد؛ جریان منحرف شده به سطح یا بطور مختصر رژیم (DSJ) و یا به صورت جت دیواره ای دوباره متصل شونده یا بطور مختصر رژیم (RWJ). در مطالعه حاضراز نرم افزار فلوئنت برای شبیه سازی جریان استفاده شده است. میدان محاسباتی با استفاده از شبکه منشوری گسسته گردیده است. برای دقت بیشتر از مدل آشفتگی هفت معادله ای RSM استفاده شد که در صحت سنجی نتایج بهتری تولید کرد. مقایسه برای سه مدل به ترتیب در شرایط پرش هیدرولیکی بدون بلوک به شکل جت دیواره ای مستغرق، پرش هیدرولیکی مستغرق در شرایط رژیم DSJ و پرش هیدرولیکی مستغرق در شرایط رژیم RWJ انجام گرفته و گردابه های شکل گرفته حول سه محور x،  y و  z و مقدار چرخش مورد بررسی قرارگرفته است. نتایج بیانگر این است که  گردابه هایی که حول محور Zها در گردش هستند، با توجه به قدرت و ابعاد بزرگتری که دارند، رژیم اصلی جریان را تعیین می کنند. این گردابه ها  در رژیم DSJ قوی تر بوده و باعث استهلاک بیشتر انرژی می شوند.}, keywords_fa = {استهلاک انرژی,پرش هیدرولیکی مستغرق,بلوکهای میانی حوضچه آرامش,شبیه سازی عددی,حوضچه آرامش}, url = {http://mcej.modares.ac.ir/article-16-1270-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1270-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {SoltaniMohammadi, Masoud and Rahimi, Sepideh}, title = {Probability distribution of relative displacement of two adjacent single degree of freedom systems}, abstract ={Seismic pounding between adjacent buildings is an undesirable phenomenon. Depending on the characteristics of the colliding buildings, pounding might cause severe structural damage in some cases, and even collapse is possible in some extreme situations. In order to mitigate the risk of seismic pounding between new buildings, current seismic design codes prescribe a minimum separation distance between adjacent structures. The value of the minimum separation distance is assumed equal to the peak relative displacement computed at the most likely pounding location and corresponding to a site-specific seismic intensity. Examining the collision possibility of adjacent structures as a result of earthquake is the basis of formulating regulations for determining minimum dimensions of separation distances. This distance can be calculated in different ways. In previous studies, double difference combination has been generally used to determine this distance and their only difference is in determining correlation coefficient of seismic response in two adjacent systems. This coefficient which depends on period and damping of the two systems has been obtained in previous works with the assumption of a linear behavior of structures. In the nonlinear range, the same correlation coefficient obtained from the linear mode is used by making structure behavior equivalent to linear mode and introducing values of effective damping and period. Modified values of period and damping depend on the requirement of system ductility under the applied record, which has been obtained for a specific behavioral model and from numerous numerical studies. In this study, the correlation coefficient of the two systems was presented using random vibration equations for the systems by Bouc - Wen different hysteresis behavior model. Moreover, the proposed relation could be applied for different input stimulation with specific spectral density and is more comprehensive than previous relations. Ductility demand of the system corresponding to the input spectral density was determined by random vibration relations and the probability distribution of relative displacement between the two systems which was obtained from the presented relations was compared with the existing ones. This study evaluates the accuracy of two different criteria to calculate the separation necessary to prevent seismic pounding between nonlinear hysteretic structural systems. All of the criteria considered in this paper make use of the same basic equation of the Double Difference Combination rule, but they adopt different procedures to estimate the correlation between displacement responses of nonlinear hysteretic systems. Monte Carlo analysis used to verify the relations presented for two adjacent nonlinear systems under the applied record which were simulated by a specified spectral density in stationary and non-stationary forms. Results obtained through Monte Carlo simulations indicate that the relation presented in this study is completely satisfactory and none of the two criteria evaluated in this study is exact.}, Keywords = {Adjacent structures,Probability equations,Bouc-Wen Model,random vibration}, volume = {14}, Number = {5}, pages = {49-63}, publisher = {Tarbiat Modares University}, title_fa = {توزیع احتمالاتی تغییرمکان نسبی دو سیستم یکدرجه آزاد مجاور هم}, abstract_fa ={بررسی احتمال برخورد سازه‌های مجاور تحت اثر زلزله، اساس تدوین ضوابط آئین نامه‌ای برای تعیین کمینه ابعاد درز انقطاع است. در پژوهش‌های پیشین از قانون ترکیب تفاضلی دوگانه برای تعیین این فاصله استفاده شده است و تنها تفاوت بین روش‌ها در تعیین ضریب وابستگی پاسخ لرزه‌ای دو سیستم مجاور هم است. این ضریب که وابسته به پریود و میرایی دو سیستم است، با فرض رفتار خطی سازه‌ها به دست آمده است، و در محدوده غیرخطی، با معادل سازی رفتار سازه با حالت خطی و معرفی مقدار پریود و میرایی موثر به دست آمده است. مقادیر پریود و میرایی موثر وابسته به مقدار نیاز شکل پذیری سیستم و تنها برای یک مدل رفتاری مشخص حاصل شده است. در این پژوهش یک الگوریتم جامع برای تعیین ضریب وابستگی بین دو سیستم با استفاده از تئوری ارتعاشات تصادفی برای سیستم با مدل رفتاری بوک- ون با رفتار های هیسترزیس مختلف، ارائه شده است. علاوه بر این، روش پیشنهادی برای انواع تحریک ورودی با چگالی طیفی‌های مشخص قابل کاربرد است و جامعیت بیشتری نسبت به روابط قبلی دارد. نیاز شکل پذیری سیستم متناظر با چگالی طیفی ورودی با استفاده از روابط ارتعاشات تصادفی تعیین و توزیع احتمالاتی تغییرمکان نسبی بین دو سیستم حاصل از روابط ارائه شده با روابط موجود مقایسه می‌شود. برای صحت سنجی روابط ارائه شده، از آنالیز مونت کارلو برای دو سیستم غیرخطی مجاور، تحت رکوردهایی که برای یک چگالی طیفی به صورت ایستا و غیرایستا شبیه‌سازی شده اند، استفاده شده است.}, keywords_fa = {ساختمان های مجاور,روابط احتمالاتی,مدل بوک-ون,ارتعاش تصادفی}, url = {http://mcej.modares.ac.ir/article-16-5334-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-5334-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Shafieefar, M. and Aghakouchak, A.A. and Moharrami, M.R.}, title = {Mass Damper and Buoyancy Functioning of a Submerged Tank on the Response of Fixed offshore Platforms}, abstract ={By increasing demand for oil in recent years, explorations from deep offshore fields are feasible. In such deep waters, even fixed offshore structures may have considerable movements under design loads, while having less displacements of the platform is often requested.  Many innovative concepts have been proposed to minimize responses of structures under environmental loads in recent decades. In a tension leg platform, the buoyancy force causes tension in the tendons, which is changed by platform movement and produces a lateral stiffness to reverse the platform into its initial position. The amount of generated additional stiffness depends on the platform displacement and buoyancy forces. Fixed submerged tanks may be used in design of a compliant platform in deep water to reduce transfer weight of the structure to the support and to decrease the effects of legs buckling. However, the tanks should be located in an appropriate water depth to minimize the effect of wave forces. In order to decrease the response of fixed offshore platforms in deep waters, an innovation concept is presented. In this concept, a submerged tank is tied up to the platform in an appropriate location acting a buoyancy force to the system. This force adds tension force to the legs which may reduce the required chord diameters and/or eliminate some braces. However, the added mass of the tank due to wave action has considerable effect on dynamic behavior of the system. In addition, the vertical buoyancy force of the tank generates a resistance moment in the system when the tank oscillates. This resistant moment depends on the location of the tank and time. In this paper, considering the effects of the tank on the platform responses, solutions for reducing platform displacement are investigated.  Analyses have been carried out by taking into account the large deflection and nonlinear geometry effects for which a MATLAB program has been developed featuring the following capabilities: Calculation of wave forces based on the Morison equation for jacket members and the Froude-Krylov method for the tank. Taking into account waves and structure interaction. Non-linear analysis of the structure considering large deformations effects. Dynamic analyses results showed that the tank acts as a weight damper under wave actions. In this case, the added mass has also contribution on the inertia force. So, there is an optimum stiffness for each mass. For dual mass damper and buoyancy functioning of the tank, the stiffness should be defined in such a way that the performance of the tank would be appropriated in both consequences. Results of analyses on a case study platform show that the performance of the tank on reducing the platform responses is much better for the dual mass damper and buoyancy functioning comparing to only the mass damper functioning.}, Keywords = {}, volume = {14}, Number = {5}, pages = {65-79}, publisher = {Tarbiat Modares University}, title_fa = {مقایسه عملکرد میراگر جرمی و مخزن متحرک مستغرق در کاهش دامنه پاسخ سکوهای ثابت دریایی}, abstract_fa ={در مقاله حاضر تاثیر یک مخزن متحرک مستغرق جهت کاهش دامنه پاسخ سکوهای ثابت دریایی که در عمق های زیاد قرار می گیرند، مورد بررسی قرار گرفته است. در این طرح ابتکاری با قرار دادن یک مخزن  متحرک توخالی با نیروی شناوری زیاد، کاهش دامنه پاسخ سکو حاصل می شود. با توجه به حجم زیاد مخزن، جرم افزوده ایجاد شده ناشی از حرکات آن مقدار بزرگی را به خود اختصاص می دهد،  لذا نیروی اینرسی تولید شده قابل ملاحظه است. از طرف دیگر نیروی شناوری مخزن که نیرویی قائم و به سمت بالا می­باشد، با نوسان مخزن تولید لنگر بازگرداننده­ای می­کند که وابسته به مکان قرار گیری مخزن یا به عبارتی زمان است. با تلفیق این دو موضوع و انتخاب سختی مناسب جهت اتصال مخزن به سکو برای عملکرد دوگانه بهینه، موجبات کاهش دامنه پاسخ سکو فراهم می شود. فرآیند تحلیل دینامیکی با در نظر گرفتن اثرات غیر خطی هندسی و تغییر شکل­های بزرگ انجام شده­است. برای این منظور، از برنامه­ای مفصل که در محیط متلب توسعه داده شده، استفاده شده­است. با انجام تحلیل­های دینامیکی مشخص شد که مخزن در مقابل امواج رفتاری شبیه یک میراگر جرمی از خود نشان می­دهد. در این حالت جرم افزوده مخزن نیز در تولید نیروی اینرسی مشارکت می­کند، لذا اینرسی زیادی تولید می­شود. نتایج بررسی های انجام شده روی سیستم پیشنهادی نشانگر آن است که کارایی مخزن با عملکرد دوگانه میراگری و شناوری بیشتر از کارایی یک میراگر تنها می باشد؛ این درحالی است که حتی میراگر، جابجایی­های به مراتب بزرگتری را نسبت به مخزن تجربه کرده­است. به هنگام عملکرد دوگانه میراگری و شناوری می توان سختی بهینه را به گونه­ای تعیین کرد که مخزن عملکرد تؤام مناسبی را در هر دو حالت داشته باشد. همچنین نتایج نشان می دهند با عبور از حالت گذرا و ورود به پاسخ­های حالت پایا عملکرد بهتری حاصل می شود.  }, keywords_fa = {سکوی ثابت,مخزن مستغرق,میراگر جرمی,عملکرد دوگانه اینرسی و شناوری}, url = {http://mcej.modares.ac.ir/article-16-9532-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9532-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Alinasab, Rez}, title = {evaluation of lime fillers effects on reduction of moisture and freeze damage by indirect tensile strength and compressive strength tests}, abstract ={Pavement performance in Iran is not compatible with expectations and demands of contemporary society. The poor performance of pavement results in shortening country roadways lifetime and paying heavy cost. One of the pavement major problems particularly in wet conditions is stripping of aggregates. Stripping is a major distress occurring in hot mix asphalt (HMA) pavements in Iran and in various parts of the world The stripping of aggregates in hot mix asphalt not only is considered as an independent problem but also it may cause damages like cracking, rutting, raveling, fatigue cracking. The moisture first inflicts damage on the HMA mix by destroying the bond between the aggregate and the asphalt binder or by destroying the internal cohesive strength of the binder. This loss of adhesion causes the asphalt concrete to ravel under traffic loads. Stripping occurs in the presence of water, so it is often referred to as moisture damage. In this paper, the effective parameters causing stripping have been identified and the methods of increasing asphalt mixture durability have been investigated, focusing on the recognition of how stripping can be made. In this regard, limestone fillers and hydrated lime have been used in different amounts as antistripping agents (which can be found widely in the country) and the optimum resistant mixture against stripping have been prepared. In this thesis two kinds of aggregate from the east and west of Tehran and two kinds of bitumen (60/70) from Tehran and Isfahan refineries have been collected and the required experiment (on aggregates, bitumen and hot mix asphalt) have been carried out. Then according to marshal method and based on ASTM D6926 and ASTM D6927 standards, marshal specimen have been made and the optimum bitumen has been determined, using the required parameters by marshal method. Using indirect tensile strength and compressive strength tests over saturated and dry specimen, according to AASHTO T283 and ASTM D1075 standards, asphalt mixture stripping potential has been investigated. Since the resistance of asphalt mixture again moisture was not satisfactory, two kinds of limestone filler and hydrated lime were used for improving asphalt mixture resistance and their effect was investigated on asphalt mixture. Hydrated lime and limestone filler, when added to the asphalt prior to preparation of the mixtures, dramatically improved mixture resistance to moisture damage for both aggregates. The results obtained from indirect tensile strength and compressive strength tests over saturated and dry specimen, according to AASHTO T283 and ASTM D1075 standards show that using 1.5% hydrated lime or 4% limestone filler (by weight of aggregates) in asphalt concrete, significantly increased the asphalt mixture resistance against stripping. Also in this study the results obtained from two experiments methods (tensile strength and compressive strength tests) are compared.}, Keywords = {Stripping,Hydrated lime,Indirect Tensile Strength,limestone filler,compressive strength}, volume = {14}, Number = {5}, pages = {77-85}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی تاثیر فیلرهای آهکی در کاهش اثرات تخریبی رطوبت و یخبندان با استفاده از آزمایش‌های کشش غیر مستقیم و مقاومت فشاری}, abstract_fa ={هدف از این تحقیق بررسی تاثیرات دو نوع فیلر آهکی (یکی پودر سنگ آهک و دیگری آهک هیدراته) بر مقاومت مخلوط های آسفالتی به خصوص در برابر عریان¬شدگی بوده است. در صورتی که چسبندگی قیر و مصالح سنگی کاهش یافته و یا از بین رود مخلوط آسفالتی دچار عریان شدگی و اضمحلال می¬ شود. این پدیده در صورت استفاده از سنگ¬های اسیدی و سیلیسی که دارای بارالکتریکی سطحی منفی هستند تشدید می¬شود. در این تحقیق مخلوط¬های آسفالتی با استفاده از مصالح سنگی کارخانه¬های شرق و غرب تهران و با درصدهای مختلف فیلرآهکی و آهک هیدراته تهیه شدند و طرح اختلاط بهینه آنها به روش مارشال به دست آمد. سپس مقاومت مخلوط¬های آسفالتی در برابر رطوبت و یخبندان با استفاده از آزمایش لاتمن اصلاح شده تحت استاندارد AASHTO T283 و مقاومت فشاری تحت استاندارد ASTM D1075 و با مقایسه مقاومت کششی غیر مستقیم و مقاومت فشاری نمونه¬ها در شرایط اشباع و خشک مورد ارزیابی قرار گرفت. نتایج نشان داد که با افزودن حدود 4 درصد فیلر آهکی و 1 تا 5/1 درصدآهک هیدراته به ترکیب سنگدانه¬ها نسبت مقاومت کششی نمونه¬های اشباع به نمونه¬های خشک افزایش یافته و میزان عریان¬شدگی سنگدانه¬ها در مخلوط¬ کاهش یافت. با افزایش بیش¬تر قیلر آهکی و آهک هیدراته، به دلیل سخت شدگی مخلوط آسفالتی، مقاومت نمونه¬ها در برابر رطوبت نیز دچار کاهش گردیدند.}, keywords_fa = {عریان شدگی,فیلر آهکی,آهک هیدراته,مقاومت کششی غیر مستقیم,مقاومت فشاری}, url = {http://mcej.modares.ac.ir/article-16-9681-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9681-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {}, title = {1-Numerical Study of Behavior of Simply Supported RC Deep Beams with Openings}, abstract ={Generally reinforced concrete deep beams are used as transfer girders, pile caps, coupling beams and foundation walls. Openings are frequently provided in RC deep beams to facilitate essential services, such as ventilating ducts, water supply and drainage pipes, network access, or even movement from one room to another. Existence of opening leads to disturbance of compressive force path from the loading point to the support. Due to the lack of experiment on deep beam with opening, code provisions do not give any explicit guidance to designing these elements with opening. So this research studies the behavior of reinforced concrete deep beams with opening using finite element methods. To this end the commercial software ABAQUS/standard was used. The accuracy of model was verified with available experimental data. in two separate parts the behavior of these members was studied. First, 68 beams with opening were modeled to study the effect of size and position of opening, arrangement of web reinforcement, ratio of clear span to depth and ratio of shear span to depth. In all of these beams depth and thickness was 750 and 100 millimeter respectively. The most effective parameter on behavior and ultimate load capacity was arrangement of web reinforcement. Also the size effect on the behavior of these members was studied. So 8 beams were modeled and result indicates that by increasing size of the beams the normalized shear strength decreases. Generally reinforced concrete deep beams are used as transfer girders, pile caps, coupling beams and foundation walls. Openings are frequently provided in RC deep beams to facilitate essential services, such as ventilating ducts, water supply and drainage pipes, network access, or even movement from one room to another. Existence of opening leads to disturbance of compressive force path from the loading point to the support. Due to the lack of experiment on deep beam with opening, code provisions do not give any explicit guidance to designing these elements with opening. So this research studies the behavior of reinforced concrete deep beams with opening using finite element methods. To this end the commercial software ABAQUS/standard was used. The accuracy of model was verified with available experimental data. in two separate parts the behavior of these members was studied. First, 68 beams with opening were modeled to study the effect of size and position of opening, arrangement of web reinforcement, ratio of clear span to depth and ratio of shear span to depth. In all of these beams depth and thickness was 750 and 100 millimeter respectively. The most effective parameter on behavior and ultimate load capacity was arrangement of web reinforcement. Also the size effect on the behavior of these members was studied. So 8 beams were modeled and result indicates that by increasing size of the beams the normalized shear strength decreases.}, Keywords = {Finite Element,ultimate load,Size effect}, volume = {14}, Number = {5}, pages = {87-99}, publisher = {Tarbiat Modares University}, title_fa = {1- بررسی عددی رفتار تیرهای عمیق بتن مسلح دو سر ساده دارای بازشو}, abstract_fa ={ به طور کلی تیر‌های عمیق به عنوان شاه‌تیر‌های حمال و سرپوش شمع‌ها و همچنین در دیوار‌ها­ی ساختمان­های بلند کاربرد دارند. برای اجرای سرویس‌های اساسی مثل کانال‌های هوا، دسترسی به کابل‌های شبکه‌های الکتریکی و کامپیوتری، تاسیسات مکانیکی و یا رفت و آمد از اتاقی به اتاق دیگر، در جان تیر‌های عمیق بتن مسلح بازشو‌ طراحی می‌کنند. در این مقاله به بررسی رفتار تیر‌های عمیق بتن مسلح دو سر ساده دارای بازشو با استفاده از روش اجزاء محدود پرداخته شده است. برای مدل‌سازی نمونه‌ها از نرم افزار Abaqus استفاده شده است. 24 تیر عمیق دارای بازشو مدل و پارامتر‌های اندازه‌ی بازشو، محل بازشو، چیدمان آرماتور جان بررسی شده است. در تمام این تیر‌ها ارتفاع و ضخامت ثابت و به ترتیب mm750 و mm100 است. بارگذاری تیرها به صورت بار متمرکز دو نقطه­ای و متقارن است. تیرهای دارای بازشوی بزرگتر مقاومت کمتری نشان می­دهند و محل بازشو تأثیر زیادی روی رفتار و مقاومت نهایی تیر­ها ندارد. بیشترین تأثیر روی رفتار و بار نهایی با تغییر چیدمان آرماتور جان ایجاد می‌شود که به ترتیب چیدمان مورب، شبکه‌ای، قائم و افقی منجر به افزایش بیشتر بار نهایی می‌شوند. به­ گونه‌ای که مقاومت چیدمان مورب آرماتور به­طور متوسط 67/1 برابر چیدمان افقی است. همچنین برای شبیه سازی تیرهای عمیق موجود در سازه­های واقعی 12 تیر عمیق با ارتفاع mm2000 و دهانه­ی خالص mm3500 و ضخامت mm220 مدل شدند. بازشو در این تیرها دارای ابعاد mm200×350 است. نتایج تحلیل نشان می­دهد که برای تیرهای عمیق با این ابعاد نیز به ترتیب چیدمان مورب، شبکه‌ای، قائم و افقی بیشترین تاثیر را در افزایش بار نهایی دارند و محل بازشو در ارتفاع تیر عمیق تاثیر زیادی روی مقاومت نهایی ندارد.}, keywords_fa = {تیر عمیق,بتن مسلح,بازشو,اجزاء محدود,بار نهایی}, url = {http://mcej.modares.ac.ir/article-16-932-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-932-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Fayezi, Amir and Moharrami, Hami}, title = {Optimal Control of Structures Equipped with MR Dampers Using ANFIS}, abstract ={Due to high capacity and low energy consumption of Magneto-Rheological (MR) dampers, they are vastly being utilized to control seismic responses of structures. Presenting more precise methods for control algorithm, and including more realistic physical chara­­cteristics of MR dampers (e.g. nonlinearities, uncertainties and …) will help engineers to employ this kind of damper more efficiently. In order to achieve a controller that quickly and accurately determines the input voltages to the MR dampers, in this paper, a new strategy is proposed. The proposed strategy utilizes Adaptive Network based Fuzzy Inference System, (ANFIS) for optimal control of structures that are equipped with MR dampers. To obtain optimal time histories of demanded voltages, a new objective functional (J) that is a combination of some control criteria including reduction of relative drifts, absolute accelerations and absorbed energy is suggested. The optimization problem is such formulated that the set of equations of motions and equations representing the nonlinear model of MR dampers (here Bouc-Wen) are solved simultaneously. The optimization problem is solved by the enhanced method of steepest descend algorithm by Moharrami and Fayezi [3]. In this way, for a 15-storey building frame subjected to two deterministic earthquakes, the time histories of optimal input voltages of dampers are numerically computed. Next, the optimal voltages associated with the data on drifts, velocities and accelerations of stories are used as desired input- output data pairs to train the ANFIS as a quick and accurate controller. Three ANFISs were trained by different weights for drift (q1) and absolute acceleration (q2) data versus voltages. The weights of q1 and q2 controlling data were assumed to be (1,0), (0,1) and (1, 0.42) for ANFIS1, ANFIS2 and ANFIS3, respectively. Finally, to establish a context for assessment of the effectiveness of the proposed strategy in comparison with other conventional methods and to analyze the effects of weights in the objective functional, two numerical cases are presented. In the first case, the aforementioned 15-storey building frame is controlled against some earthquakes which were not applied for training process of ANFIS. Results show that ANFIS1 has decreased maximum and time-averaged relative drifts more than other control methods. In addition, this controller has somehow attenuated base shear similar to passive-on but has not been successful in reduction of absolute acceleration values. The ANFIS2 has controlled absolute accelerations better than other controllers whereas drifts have been reduced fairly well. By the ANFIS3, one can achieve reasonable decrease in all controlling criteria. Their values are between ANFIS1 and ANFIS2. It can be concluded that depending on the relative importance of control on drifts or accelerations of stories, one can chose proper weights for q1 and q2. In the second example, a benchmark six-storey building that is equipped with 2 dampers in the first, and 2 dampers in the second storey, has been controlled by the three proposed controllers. The results are compared with several conventional methods. The proposed strategy show more flexibility in reduction of the structural control criteria in comparison with some other conventional methods.  }, Keywords = {ANFIS,Optimal Control,MR damper,ANFIS,objective function,shear frame}, volume = {14}, Number = {5}, pages = {101-113}, publisher = {Tarbiat Modares University}, title_fa = {کنترل بهینه ساختمانهای مجهز به میراگر MR با استفاده از شبکه عصبی فازی ANFIS}, abstract_fa ={در این مقاله استراتژی کنترل بهینه ساختمانهای مجهز به میراگر MR با استفاده از شبکه عصبی فازی ANFIS ارائه گشته است. ابتدا یک تابعک هدف (J) پیشنهاد گشته و از معادلات دینامیکی سازه به همراه میراگر MR به عنوان قیود آن استفاده گردیده است. با حداقل کردن این تابعک هدف، تاریخچه زمانی بهینه ولتاژهای اعمالی به میراگرها بدست آورده شده است. از این ولتاژها و پاسخهای سازه¬ای متناظر، برای آموزش ANFIS استفاده شده است. با به کار گیری ANFIS می¬توان به سرعت و به دقت ولتاژهای بهینه¬ی میراگرها را در حین وقوع زلزله واقعی تعیین نمود. برای نمونه، یک قاب برشی 15 طبقه توسط ANFIS کنترل شده است. نتایج حاصل، کاهش مناسبی را در حداکثر و میانگین زمانی دریفت نسبی طبقات و برش پایه نسبت به حالت کنترل نشده و کاهش قابل توجهی را در حداکثر و میانگین زمانی شتاب مطلق طبقات نسبت به حالت کنترل شده به صورت غیر فعال نشان می¬دهد.}, keywords_fa = {کنترل بهینه,میراگر MR,تابع هدف,قاب برشی}, url = {http://mcej.modares.ac.ir/article-16-4289-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-4289-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Komakpanah, Ali and Khakpour, Komeil and noroozOlyaei, Mohamm}, title = {Investigation of effect of the liquefiable layer geometry in behavior of pile Foundations}, abstract ={Lateral ground displacement due to liquefaction causing damages to major infrastructures like buildings, bridges, pipe, shore line utilities etc. When the surface slope is mild, a common mode of failure is lateral spreading with surface displacements that can exceed several meters. Considering the widespread use of pile foundations, their safety in the occurrence of earthquake has a special importance. Studies after the earthquake have shown that both the force due to structure and the Kinematics interaction between the pile foundations and the soil play an important role in mechanical behavior of piles. Since the effect of the superstructure on the pile-soil interaction analysis is significant; the analysis should be done based on the interaction axis of pile-soil-structure. In this study, finite difference method (FDM) has been used to investigate the effect of the thickness of liquefied layer, slope of liquefied layers and the underground water level on behavior of pile foundations. Results indicate that with an increase in the slope of liquefied layers, the maximum bending moment raises but the slope of this graph for low underground water level (near the surface) is higher. This type of behavior also is observed in the shear force created in the pile foundation.}, Keywords = {Pile,Liquefied soil,Finite Difference,Dynamic Analysis,Pile and soil interaction}, volume = {14}, Number = {5}, pages = {127-135}, publisher = {Tarbiat Modares University}, title_fa = {بررسی تاثیر مشخصات هندسی لایه روانگرا در رفتار پی‌های شمعی}, abstract_fa ={جابه­جایی­های ناشی از روانگرایی باعث خسارت­های عمده­ای به زیرساخت­ها، مانند ساختمان­ها، پل­ها، لوله­های مدفون و ... می‌شود. وقتی سطح زمین دارای شیب باشد امکان وقوع پدیده گسترش جانبی در خاک­های روانگرا وجود دارد که باعث جابه­جایی­هایی تا حد چند متر نیز می­شود. با توجه به کاربرد وسیع پی­های شمعی، ایمنی شمع­ها در زمان زلزله از اهمیت ویژه­ای برخوردار است. مطالعات پس از وقوع زلزله در خاک روانگرا نشان داده است که هم نیروی ناشی از سازه و هم اندرکنش سینماتیکی بین شمع و خاک نقش مهمی در رفتار مکانیکی شمع­ها دارد، در نتیجه باید تحلیل براساس اندرکنش شمع – خاک – سازه صورت گیرد.  در این پژوهش از روش تفاضل محدود (FDM)، برای بررسی تأثیر ضخامت لایه روانگرا، شیب لایه روانگرا و تراز آب زیرزمینی بر پی­های شمعی استفاده شده است. نتیجه آن است که با افزایش شیب لایه روانگرا، لنگر خمشی ماکزیمم، افزایش می­یابد ولی شیب این نمودارها در ترازهای آب پایین (نزدیک به سطح زمین) بیشتر است. این نوع رفتار در نیروی برشی ایجاد شده در شمع­ها نیز مشاهده شده است.}, keywords_fa = {شمع,خاک روانگرا,تفاضل محدود,تحلیل دینامیکی,اندرکنش خاک و شمع}, url = {http://mcej.modares.ac.ir/article-16-4502-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-4502-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Mokhtarani, Nader and Khodabakhshi, Saeid and Ayati, Bit}, title = {UV-TiO2 Photocatalytic Degradation of Compost Leachate}, abstract ={UV-TiO2 Photocatalytic Degradation of Compost Leachate Abstract The growing rate in solid wastes production leads to considerable generation of leachate. Leachate is defined as the aqueous effluent generated as a consequence of precipitation percolation through wastes, biochemical processes in wastes body and the inherent water content of wastes themselves. Since the leachate contains significant amount of organic and inorganic compounds, it is not allowed to be directly discharge to the environment. Conventional treatment techniques to remove organic matters from leachate include physical, chemical and biological processes. Most of these techniques are non-destructive and do not solve the environmental problems because the wastes are simply transferred from water to another phase creating secondary wastes pollution. Biological method was regarded as the most efficient and cheapest process to eliminate organic materials from leachate. However, biological process cannot usually remove refractory substances. Therefore, the effluent values of the organic content do not meet the standards of the treated wastewater with respect to persistent contaminants. Due to limited biodegradability, the treatment of leachate, apart from biological methods necessitates the application of other methods, which complement and support the main process. Advanced oxidation process has been intensively studied in the past decade to improve the removal of these large refractory organic molecules or to transform them into more easily biodegradable substances. Among them photocatalytic process is one of the appropriate methods for final treatment of these kinds of waste. In this study, application of photocatalytic process via UV light and TiO2 Nano particles immobilized on concrete surface in post-treatment of composting leachate was investigated. This investigation was conducted in laboratory scale and batch mode. A biological pre-treated leachates sample which contains some macromolecular organic substances that were resistant to biological degradation were collected from the effluent of leachate treatment facility, of Gorgan composting plant (Golestan, Iran). UV-C lamps with different power in the range of 8-107 W at a constant distance of 10 cm from the surface of the leachate were used as the source of irradiation. Pervious concrete was constructed using LECA lightweight aggregates with the dimension of 30*10*10 cm. Immobilization of TiO2 on concrete surface was done by using concrete sealer. In order to investigate the effect of each parameter individually, some experiments were carried out. The results showed that the presence of nanoparticles and UV radiation alone did not significantly affect on the COD removal. According to the conducted experiments the maximum COD removal of 62% was achieved after 20 hr radiation with 7.5 mW.Cm-2 intensity in pH value of 5 and in presence of 60 g.m-2 of TiO2 coated on concrete. According to Iranian environmental standards and with regard to organic loading of leachate, removal efficiency of this process was in such a way that it could be directly discharged into the environment. Keyword: Leachate treatment, Photo Catalysis reaction, TiO2, light intensity, Color, COD}, Keywords = {COD,Leachate treatment,Photo Catalysis reaction,TiO2,Color,COD}, volume = {14}, Number = {5}, pages = {137-146}, publisher = {Tarbiat Modares University}, title_fa = {تصفیه تکمیلی شیرابه کمپوست با استفاده از فرایند فتوکاتالیستی UV/TiO2}, abstract_fa ={یکی از اقدامات لازم در خصوص مدیریت پسماند، جمع­آوری و تصفیه شیرابه است. تاکنون از روش­های مختلفی برای تصفیه شیرابه استفاده شده که یکی از این روش­ها که به تازگی مورد توجه قرار گرفته، فرایند فتوکاتالیستی است. در این پژوهش تصفیه تکمیلی شیرابه کمپوست با استفاده از نانو ذرات TiO2 تثبیت شده بر بستر بتنی و با تابش نور UV، در مقیاس آزمایشگاهی بررسی شد. شیرابه استفاده شده از خروجی تصفیه‌خانه یکی از مراکز تولید کمپوست کشور که در دو مرحله تصفیه بیولوژیکی می‌شود تامین شد. در این فرایند از لامپ­های UV-C با توان­های مختلف در محدوده 107-8 وات که در فاصله ثابت 10 سانتی‌متر از سطح شیرابه قرار داشت استفاده شد. ابتدا به منظور تعیین تاثیر هر یک از پارامترهای اصلی موثر بر فرایند، آزمایش­های شاهد در شرایط تاریکی مطلق، بستر بتنی بدون پوشش نانو ذرات و اشعه UV تنها انجام، و تاثیر هر یک از عوامل مذکور به صورت مجزا بر حذف بار آلی از شیرابه ارزیابی شد. در ادامه تاثیر هم‌زمان عوامل یاد شده مورد بررسی قرار گرفته و در شرایط بهینه بیشینه حذف COD و رنگ به ترتیب 62 و 33 درصد در 5pH=، زمان ماند 20 ساعت، پوشش دهی نانو ذرات به میزان 60 گرم بر متر مربع و با استفاده از لامپ UV با توان 77 وات حاصل شد. با در نظر گرفتن استانداردهای سازمان حفاظت محیط زیست کشور، فرایند فتوکاتالیستی UV/TiO2قادر به کاهش بار آلی شیرابه برای استفاده در کشاورزی است.}, keywords_fa = {تصفیه شیرابه,فرایند فتوکاتالیستی,دی‌اکسید تیتانیوم,رنگ}, url = {http://mcej.modares.ac.ir/article-16-951-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-951-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Mamdoohi, Amirreza and Saffarzadeh, Mahmood and bazargany, A}, title = {Optimized Linear Programming for Ramp Metering, Case Study}, abstract ={  Freeways have a particular role in urban transportation networks due to their high capacity compared to other facilities of lower hierarchical classification. Although these facilities do not have any at-grade junctions and are of the highest mobility and least access classification, their flow control can help general urban traffic condition. Traffic control strategies are thus of particular importance to urban transportation. Ramp metering of urban freeways and highways is one of the efficient traffic control policies that can alleviate traffic congestion by restricting on-ramp flows to the main stream. A main challenge of this policy is the determination of optimal flow rates of the on-ramps leading to optimal flow rate of the main stream. In this paper, a linear programming model is developed considering the capacity constraint of the main stream and the constraints of queue length of ramps. Although the queue length of the on-ramps increase due to the ramp metering strategy by holding up vehicles on these ramps, the travel time of the main stream as the main body of traffic whose traffic condition is of higher importance, decreases due to the increase in the speed of this stream caused by the drop in vehicle density. The main objective of this paper is the implementation of a mathematical programming model developed for a rather congested case study in Tehran; and the analysis of its challenges and impacts. This model takes into account the maximization of flow in the transportation network while flow conservation and capacity constraints are not violated. In the field survey, flow rate data of about 15000 vehicles west-bound of Shahid Hemmat highway segment from Modares freeway to Shahid Chamran off-ramp were gathered for three hours. This segment includes five on-ramps and four off-ramps whose flow rate data along with that of the main stream was collected on a Tuesday in summer 2011. The data was collected through video recording and then obtaining the necessary variables like flow rate data by re-watching the films carefully and counting the vehicles. Although very time and budget consuming, but this survey method made possible the data collection phase to be valid and reliable. Flow rates for 5 minute time intervals for all the ramps and the main stream were obtained to comprise part of the research data base. Capacity, as a model parameter, was predicted for the segment under study. Results of the mathematical programming optimization model indicate that level of service of the segment under study increases from F to E and that the speed in the main stream increases between 18 and 24 kilometers per hour and that travel time in this segment has a decrease of nine minutes. Results of the optimization model indicate that freeway traffic performance can be optimized by careful management of on-ramp monitoring and control realized through ramp metering strategy, emphasizing quantitatively and scientifically the importance and necessity of detailed traffic data and its analysis for the betterment of traffic conditions through merely management techniques which do not require much time or budget to use the existing facilities more efficiently. .}, Keywords = {"Ramp metering","Optimization","Linear Programming"}, volume = {14}, Number = {5}, pages = {147-158}, publisher = {Tarbiat Modares University}, title_fa = {توسعه مدل برنامه‌ریزی خطی جهت کنترل بهینه رمپ‌ها: مطالعه موردی بزرگ‌راه شهید همت}, abstract_fa ={ کنترل رمپ در بزرگراه‌های شهری یکی از سیاست‌های کنترل ترافیک کاراست که می‌تواند وضعیت ازدحام بزرگراه‌ها را با محدود کردن تعداد خودروهای ورودی به بزرگراه بهبود بخشد. چالش اصلی این استراتژی، تعیین نرخ‌های بهینه ورود وسایل نقلیه به تفکیک رمپ‌های مختلف به مسیر اصلی است به گونه‌ای که منجر به حداکثر حجم تردد در مسیر اصلی شود. در این تحقیق، یک مدل برنامه‌ریزی خطی جهت کنترل بهینه رمپ‌ها با توجه به محدودیت ظرفیت مسیر اصلی و محدودیت طول صف در رمپ‌های ورودی توسعه یافته است. هدف اصلی این تحقیق پیاده‌سازی و اجرای مدل برنامه‌ریزی ریاضی توسعه‌یافته برای یک نمونه واقعی و پرازدحام در شهر تهران و بررسی چالش‌ها و آثار آن است. در عملیات میدانی نسبتاً وسیع شامل گردآوری داده‌های حجم تردد بزرگراه شهید همت تهران رویکرد شرق به غرب حد فاصل بزرگراه مدرس تا خروجی بزرگراه شهید چمران و رمپ‌های در این محدوده در مدت 3 ساعت، حدود 15000 خودروی عبوری شمارش شدند. نتایج اجرای مدل برای این محدوده نشان‌دهنده بهبود سطح سرویس مسیر اصلی از F به E و افزایش سرعت در مقاطع اصلی آزادراه بین 18 و 24 کیلومتر در ساعت و همچنین کاهش زمان سفر در مسیر اصلی به مقدار 9 دقیقه است.}, keywords_fa = {"کنترل رمپ","بهینه سازی","برنامه ریزی خطی"}, url = {http://mcej.modares.ac.ir/article-16-3759-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-3759-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {sh, sh}, title = {A Numerical Study on Uniaxial Behavior of Aluminum Replicated Foams with Regular Microstuctures}, abstract ={It is a decade that replication process has gained lots of interests in the production of open-cell metallic foams. Replication process usually involves the steps of preparing porous preform, filling the free spaces by foaming material, and removing the space-holders (usually by dissolution). Independent control of pore size, pore shape, and relative density, the possibility of producing foams with pores of few microns, nearly fault free and uniform structures critical in conducting reproducible mechanical tests, applicability to various metal and alloys, and the simplicity of producing functionally graded structures are some of the benefits making replication process quite appealing for researchers involved in the field of cellular solids. This study assumes that the space-holders are initially monomodal spheres packed in regular simple cubic (sc), body-centered cubic (bcc), and face-centered cubic (fcc) configurations. However, the primary shapes and structures of these assemblies undergo considerable changes in the process of compaction. Thus, the realistic numerical simulation of replicated foams is required to address this compressing stage. Accordingly, the physical processes of cold isostatic pressing and preform removal (dissolution) is simulated using nonlinear finite element method and voxel element method, respectively. A code is written to take the deformed shape of a preform (as a set of finite elements), efficiently invert the geometry, and create the FE model of replicated structure as a set of voxel elements. Three pore sizes of 0.1, 1, and 10 mm are assumed. The corresponding unit cells are compressed to reach the desired void volume fractions of around 5 to 25%. Assuming an aluminum alloy as the foaming material, uniaxial compressive load is applied to the samples and their elastic moduli, Poisson’s ratios, and yield stresses are extracted. In the range of preforms and pore sizes simulated, no cell size dependency of the results has been observed. The fcc structure, owing to its oblique beam-like elements, shows the most flexible behavior. On the other hand, the sc structure is found the stiffest in the group. The dependencies of elastic and yield properties to relative density increase by migrating from the sc to the bcc and next to the fcc structures. More in-depth study of the results reveals that the bcc samples of higher relative densities have inherent elastic behaviors near those of the sc specimens. From yield stress point of view, the bcc and fcc foams are found superior and inferior, respectively. The computed yield stresses are also compared to some previously reported analytical estimations from which the strength level of each structure is identified. The power law exponents of numerically calculated yield points are shown to be less than their empirical counterparts. This is attributed to the random structure of actual foams and their imperfect struts. Finally, it needs to note that, the extended application of the developed computational procedure to the random assemblies of spherical preforms is already under investigation.}, Keywords = {replicated foam,Numerical simulation,uniaxial compression,finite element method,voxel element}, volume = {14}, Number = {5}, pages = {159-170}, publisher = {Tarbiat Modares University}, title_fa = {بررسی عددی رفتار تک محوری فوم آلومینیومی بازتولیدی با ریزساختار منظم}, abstract_fa ={در این پژوهش، خواص تک محوری فوم آلومینیومی بازتولیدی با ریزساختار منظم به صورت عددی محاسبه و مورد ارزیابی قرار گرفته است. به منظور شبیه¬سازی ساختار چنین ماده¬ای، سعی گردیده فرآیند تولید آن با استفاده از روش¬های عددی مناسب شبیه¬سازی شود. به همین منظور و در گام نخست، روش اجزای محدود غیرخطی برای شبیه¬سازی فرآیند متراکم کردن ماده¬ی مولد و تعیین هندسه¬ی ریزساختار آن در یک نسبت حفره¬ی مشخص به کار رفته است. در گام دوم، هندسه به دست آمده با بکارگیری المان¬های وکسل معکوس سازی می¬گردد و با اعمال خصوصیات ارتجاعی- خمیری آلومینیوم و شرایط تکیه¬گاهی مناسب، آماده تحلیل نهایی می¬شود. در تولید ماده¬ی مولد از کره‌هایی با اندازه برابر و رفتار صلب خمیری کامل با سه قطر 1/0، 1 و 10 میلیمتر و در سه آرایش استاندارد جامدات کریستالی sc، bcc و fcc استفاده شده که بر اساس هر یک از آن¬ها و با اعمال فشار هیدروستاتیکی مناسب، فوم-هایی با پنج چگالی نسبی تقریبی 5، 10، 15، 20 و 25% تولید گردیده است. در پایان و پس از اعمال فشار تک محوری به صورت جابجایی-کنترل، خواص مکانیکی نمونه¬ها شامل مدول ارتجاعی، نسبت پواسون و نقطه تسلیم استخراج و بررسی می¬شود.}, keywords_fa = {فوم بازتولیدی,مدل‌سازی عددی,فشار تک محوری,روش اجزا محدود,المان وکسل}, url = {http://mcej.modares.ac.ir/article-16-9301-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9301-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {}, title = {Amelioration of the nonlinear seismic responses of RC structures based on the yield displacement (On the Comparison of CSA and YPS analysis methods)}, abstract ={Abstract Seismic performance evaluation of different structures requires nonlinear analysis utilizing static or dynamic methods. Among the dynamic nonlinear methods is the time history (TH) method can be noted. Performing dynamic nonlinear methods is not decree because of these methods has complex process and need long time to perform so often engineers do evaluations of seismic performance of different structures by using static nonlinear methods. In static nonlinear methods, capacity spectrum analysis using the concept of nonlinear spectra with constant ductility (CSA) and yield point spectrum analysis (YPSA) can be pointed. Both of these methods determine maximum displacement of structure by comparison capacity spectrum and demand spectrum but YPS method is easier than CSA and need lesser attempts. In additional of this advantage YPSA can be used in design. In order to Performing any of these Methods seven records is needed as history of the sever ground motions. These records are proportionate with the soil of type II. To allow comparison and homogenization of results of these methods scaling of the records is necessary. Also in scaling process the effect of vertical component of ground motion is neglected. In this paper the accuracy of CSA and YPS methods in determining the structural responses, has been assessed by their comparison with the TH method as the witness and accurate method of analysis. In this comparison is used the average of the results. Results include of Displacement of roof of the structures and Inter-story drifts. For this purpose, three 3D structural models of 8, 12 and 15 stories of moderate ductility were selected. These structures consist of a dual system (wall-frame) in one direction and moment resistant system in another direction of the plan against seismic load. All these structures were analyzed and designed according to the Iranian standard 2800 (IS-2800) for seismic analysis and Iranian concrete code of practice respectively. For 12 and 15 stories structures, all records scaled base on demand spectrum given by IS-2800. In the case of 8 story structure the records scaled base on equal maximum acceleration (0.4g). All structures analyzed utilizing all the methods of TH, CSA and YPSA. In all these analysis the flexural and axial behavior of elements and the shear behavior of the walls were considered nonlinear. Also in the both nonlinear static methods, the strength reduction in the demand spectrum of applied earthquakes was not taken into consideration. Results show that the YPSA method is not accurate enough in case of the earthquakes that cause the structure to largely enter the nonlinear state. Also this method is highly sensitive to the yield displacement for determining the response. Thus, strategies to address these deficiencies are presented. It’s also been shown that the best range for considering the yield displacement in dual system of concrete structures up to 50 meter height is 0.6% to 0.8% of the height of structures. Key Words: Capacity Spectrum Method, Yield Point Spectrum, Time History Nonlinear Analysis, Dual System, Reinforced Concrete Structures}, Keywords = {Capacity Spectrum Method",Yield Point Spectrum",Time History Nonlinear Analysis",Dual System"Reinforced Concrete Structures "}, volume = {14}, Number = {5}, pages = {171-181}, publisher = {Tarbiat Modares University}, title_fa = {بهبود پاسخ تحلیل‌های غیرخطی لرزه‌ای سازه‌های بتن مسلح برمبنای تعیین جابجایی تسلیم (مقایسه روش‌های طیف نقطه تسلیم و طیف ظرفیت)}, abstract_fa ={ارزیابی عملکرد لرزه¬ای سازه¬های مختلف نیازمند انجام تحلیل¬های غیرخطی (استاتیکی و دینامیکی) است. از روش¬های تحلیل دینامیکی غیرخطی می¬توان به تحلیل تاریخچه زمانی (TH) و از روش¬های تحلیل استاتیکی غیر¬خطی می¬توان به تحلیل طیف ظرفیت با استفاده از مفهوم طیف غیر¬خطی با شکل¬پذیری ثابت (CSA) و تحلیل طیف نقطه تسلیم (YPSA) اشاره کرد. در ارزیابی عملکرد لرزه­ای سازه­های مختلف نیازمند انجام تحلیل­های غیرخطی (استاتیکی و دینامیکی) است. از روش­های تحلیل دینامیکی غیرخطی می­توان به تحلیل تاریخچه زمانی (TH) و از روش­های تحلیل استاتیکی غیر­خطی می­توان به تحلیل طیف ظرفیت با استفاده از مفهوم طیف غیر­خطی با شکل­پذیری ثابت (CSA) و تحلیل طیف نقطه تسلیم (YPSA) اشاره کرد. در این مقاله دقت دو روش CSA و YPSA در تعیین پاسخ به عنوان روش اصلی نسبت به روش TH به عنوان روش شاهده و دقیق، مورد مقایسه قرار گرفته­است. به این منظور 3 سازه ساختمانی سه بعدی با تعداد طبقات 8، 12 و 15 با شکل­پذیری متوسط که در یک جهت شامل سیستم دوگانه (قاب-دیوار) و در جهت دیگر شامل سیستم مقاوم قاب خمشی است، انتخاب شده­اند. هر یک از این سازه­ها ابتدا بر اساس استاندارد 2800 و آیین­نامه بتن ایران تحلیل و طراحی و سپس با سه روش  CSAو YPSA و TH تحلیل شدند. نتایج به دست آمده نشان می­دهد روش YPS در زلزله­هایی که سازه را تا حد زیادی وارد ناحیه غیرخطی می­کند، دقت کافی ندارد. همچنین این روش برای تعیین پاسخ، حساسیت بالایی به جابه‌جایی تسلیم تعیین شده دارد. از این رو راهکارهایی برای رفع این کاستی­ها ارائه شده است. در ادامه نشان داده شده است که بهترین بازه برای در نظر گرفتن جابه‌جایی تسلیم در سازه­های دوگانه بتن مسلح تا حداکثر ارتفاع 50 متر 0.6% تا 0.8% ارتفاع سازه است.}, keywords_fa = {طیف ظرفیت",طیف نقطه تسلیم",تحلیل غیرخطی تاریخچه زمانی",جابجایی تسلیم",سازه دوگانه بتن مسلح"}, url = {http://mcej.modares.ac.ir/article-16-8485-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-8485-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {yazdandoust, majid and yazdani, mahmoo}, title = {Experimental Study on Combined effects of microsilica weighted ratio content, fineness modulus of aggregates and water-cement ratio on mechanical and physical properties of concrete}, abstract ={Concrete properties are dependent on many parameters such as ingredients, production and technology, construction methods and curing conditions that have made concrete as a complex and unpredictable material. But these are virtually ignorable against its precious advantageous and precise studies on above parameters may help us to produce concretes with our desirable properties. Ingredients are of those important parameters that play an essential role. Therefore it is seriously important to have enough knowledge about ingredients, their combined effects and interactions and also effects of their properties on concrete properties. Pozzolan materials can help us to achieve desirable characteristics of concrete and develop its mechanical and physical parameters, hence they are used widely. Improvement of mechanical parameters, permeability reduction, and durability increase are among their fabulous benefits of application. They are deemed as essential ingredients of high durable and strength concretes. Pozzolan weighted ratio is major parameters which develop a homogenous and united medium and improve the physical and mechanical parameters of concrete. The effects of pozzolan on physical and mechanical properties of concrete, moreover it’s specifications, depend on the parameters of other ingredients, such as type of aggregates, particle size distribution of aggregates, fineness modulus of fine aggregates, water-cement ratio, cement type and ect. Then study of combined effects of pozzolan specifications and parameters of other ingredients is inevitable for achieving to a concrete with ideal parameters. As we know, microsilica is the most popular pozzolan material which is used widely and it’s parameters and other ingredients parameters (such as type of aggregates, particle size distribution of aggregates, fineness modulus of fine aggregates, water-cement ratio, cement type and ect) have combined effects on the variation of concrete physical and mechanical parameters. So, in this study we selected microsilica as a pozzolan to determine the combined effects of its weighted ratio content, fineness modulus of fine aggregates and water-cement ratio on physical and mechanical properties of concrete. In this study, the combined effects of microsilica weighted ratio content, fineness modulus and water-cement ratio on physical and mechanical properties of concrete were investigated. For determination the effects of microsilica weighted ratio content on concrete parameters in different water-cement ratios and particle size distributions, 5 different microsilica weighted ratio contents, 3 water-cement ratios and 3 particle size distributions, were selected and totally 45 mix designs were prepared and subjected to slump test and compressive strength, tensile strength and modulus of elasticity tests. Obtained results show a direct relationship between microsilica weighted ratio content and physical and mechanical properties of concrete. Increase in microsilica content from 0% to 10 % in all water-cement ratios and fineness modulus, leads to slump decrease and mechanical parameters increase, while from 10 % to 20 % of microsilica content, mechanical properties fall down, but the reduction trend of slump continues. Also it can be seen that the effect of different weighted of microsilica, on physical and mechanical properties of concrete, reduces by increasing in water-cement ratio and intensifies with increment of fineness modulus of fine aggregates.}, Keywords = {microsilica,fineness modulus,water-cement ratio,concrete mechanical and physical properties}, volume = {14}, Number = {5}, pages = {183-195}, publisher = {Tarbiat Modares University}, title_fa = {بررسی تأثیر متقابل نسبت وزنی میکروسیلیس، مدول نرمی سنگدانه و نسبت آب به سیمان بر پارامترهای فیزیکی و مکانیکی بتن}, abstract_fa ={در این پژوهش با مطالعه آزمایشگاهی تأثیر با هم نسبت وزنی میکروسیلیس، مدول نرمی سنگدانه و نسبت آب به سیمان بر پارامترهای فیزیکی و مکانیکی بتن بررسی شده است. به این منظور با استفاده از 5 نسبت وزنی میکروسیلیس، 3 نسبت وزنی آب به سیمان، و 3 نوع دانه‌بندی از مصالح سنگی با مدول نرمی متفاوت، 45 طرح اختلاط مختلف طراحی و مورد آزمایش اسلامپ، وزن مخصوص، مقاومت فشاری، مدول الاستیسیته و مقاومت کششی قرار گرفت. نتایج به دست آمده بیانگر تأثیر مستقیم نسبت وزنی میکروسیلیس برخواص فیزیکی و مکانیکی بتن است، به این صورت که افزایش نسبت وزنی میکروسیلیس از 0 تا 10 درصد در تمامی نسبت‌های آب به سیمان و مدول نرمی سنگدانه، کاهش اسلامپ و افزایش خواص مکانیکی بتن را به همراه دارد حال آنکه ضمن ادامه یافتن روند کاهش اسلامپ با افزایش نسبت وزنی میکروسیلیس از 10 تا 20 درصد، پارامترهای مکانیکی بتن با اُفت مواجه می­شود. همچنین مشاهده می­شود که میزان تأثیر پذیری پارامترهای فیزیکی و مکانیکی بتن از تغییرات نسبت وزنی میکروسیلیس، با افزایش نسبت آب به سیمان کاهش و با افزایش مدول نرمی سنگدانه، افزایش می­یابد..}, keywords_fa = {میکروسیلیس,نسبت آب به سیمان,مدول نرمی سنگدانه,پارامترهای فیزیکی,پارامترهای مکانیکی}, url = {http://mcej.modares.ac.ir/article-16-11863-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11863-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {khalilinadji, farib}, title = {The application of activated carbon produced from used newspaper in the removal of methylene blue dye from aqueous solution: isotherm, kinetic and thermodynamic study}, abstract ={Activated carbon is widely used at various industrial processes such as water and wastewater industries. Activated Carbon (AC) is an adsorbent which is mostly employed for removing dye from aqueous solutions because of its excellent adsorption properties. Therefore, AC is used in the adsorption process in order to remove different pollutants from the wastewater, especially colored contaminants. however; the use of commercial grade of activated carbon is faced with difficulties due to the high price of raw materials. The used newspaper found as a main component of solid wastes can be used for producing of activated carbon. One of the most important industrial pollutants, especially in textile industries, is the dyes that even at low concentrations of one parts per million (ppm) are recognizable by naked eyes. One of the mostly consumed materials in the dye industry is Methylene Blue (MB) which is used for cotton and silk dyeing. Up to now, a great number of methods have been proposed in order to remove dyes from the industrial waste water, among which adsorption is the most acceptable due to its cost effectiveness and the possibility of usage in large scales. The aim of this study is to evaluate the performance of activated carbon produced from the used newspaper for the removal of methylene blue dye in aqueous solution. KOH solution (weighted ratio of 1:3) was used to activation. The carbonization process was applied at 500˚C with the rate of 17˚C/min. After carbonization, the sample was cooled down to room temperature and then washed with distilled water until the pH of the filtered water was stabilized at 7.5. N2 adsorption at 77K is used to characterize the produced activated carbon using BET isotherm. To evaluate the performance of methylene blue dye removal, the Langmuir, Freundlich, Temkin and Redlich-Peterson isotherms with pseudo-first and pseudo-second order and inter-particle diffusion kinetic models were used. Thermodynamic parameters such as enthalpy (ΔΗ˚), entropy (ΔS˚) Gibbs free energy (ΔG˚) were also calculated. Based on the results, the values of SBET and VTOTAL were obtained 66.01 m2/g and 0.063 ml/g, respectively. According to the R2 and sum of squares for error (SSE%) values and regression curves, the optimum isotherm and kinetic model were determined Freundlich and pseudo-second order ones, respectively. In addition, qmax constant was obtained 68.03 mg/g for Langmuir isotherm. Kinetic parameters showed the adsorption of methylene blue dye on the activated carbon is endothermic and spontaneous. Also, (ΔG˚) in physical adsorption was changed from 0 to -20 kJ/mol, while the amount of the chemical adsorption will changed between -80 to -400. Finally, the activated carbon obtained from used newspaper in this study showed a better specific surface area and adsorption capacity for methylene blue dye adsorption in compared with other grades. Thus, the production of activated carbon from used newspaper should be considered as a cheaper and more effective alternative.}, Keywords = {Used newspaper,Activated carbon,Methylene blue,Kinetic,Thermodynamic}, volume = {14}, Number = {4}, pages = {1-9}, publisher = {Tarbiat Modares University}, title_fa = {کاربرد کربن فعال حاصل از روزنامه باطله در حذف رنگ متیلن بلو از محیط آبی: مطالعه ایزوترمی، سینتیکی و ترمودینامیکی}, abstract_fa ={-کربن فعال به گونه‌ای گسترده در صنایع استفاده می‌شود. یکی از محدودیت‌های استفاده از کربن فعال پرهزینه بودن پیش ماده تولیدی آن است. این مطالعه با هدف ارزیابی کارایی کربن فعال تولید شده از روزنامه باطله در حذف رنگ متیلن بلو از محیط آبی انجام شده است. برای فعال‌سازی از محلول KOH و به‌منظور تعیین خصوصیات بافت کربن فعال تولیدشده، از جذب گاز N2 در دمای ºK 77 و ایزوترم BET استفاده شده است. برای تعیین خصوصیات جذب رنگ متیلن بلو روی کربن فعال، از مدل‌های ایزوترمی لانگمیر، فروندلیچ، تمکین، ردلیچ- پترسون و همچنین مدل‌های سینتیکی شبه درجه اول، شبه درجه دوم و انتشار داخل ذره‌ای استفاده شده است. پارامترهای ترمودینامیکی آنتالپی(ΔΗ˚)، آنتروپی(ΔS˚) و انرژی آزاد گیبس(ΔG˚) محاسبه شد. بر اساس نتایج به دست آمده، مقادیر SBET و VTOTAL به ترتیب m2/g 01/66 و ml/g 063/0 به دست آمد. بر اساس مقادیر R2، آنالیز خطا (SSE% و X2) و همچنین نمودارهای تعیین برازش، مدل‌های فروندلیچ و شبه درجه دوم به ترتیب به عنوان مدل‌های بهینه ایزوترمی و سینتیکی تعیین شد. پارامترهای ترمودینامیکی نشان داد که جذب رنگ متیلن بلو گرماگیر و خود به خودی است. کربن فعال تولیدشده از روزنامه باطله در این مطالعه در مقایسه با نمونه‌های دیگر از سطح مخصوص مطلوب‌ و ظرفیت جذب سطحی مناسب‌ برای رنگ متیلن بلو برخوردار بود.}, keywords_fa = {روزنامه باطله,کربن فعال,متیلن بلو,سینتیک,ترمودینامیک}, url = {http://mcej.modares.ac.ir/article-16-10310-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-10310-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {JafariSahnehsaraii, Mohammad ali and HosseiniHashemi, Behrokh}, title = {Cyclic Behavior and Backbone Curves for Batten Columns}, abstract ={In this paper, the cyclic behavior and available ductility of batten columns subjected to constant axial and cyclic lateral load (seismic condition) and their failure mode are evaluated numerically using nonlinear finite element analysis. The column specimens were steel I-shape sections and were analyzed as an equivalent cantilever column. Batten columns are compression members composed of two or more similar longitudinal components (chords) that are connected at points along their length with batten plates as transverse connectors. These connectors ensure that the column behaves as one integral unit to achieve maximum axial capacity. In the past decades, many research activities were conducted on the buckling problem of batten columns. When a batten column is subjected to lateral load or bending moment about its hollow axis (axis perpendicular to battens) in addition to axial compression, the additional internal actions will be imposed to its members (chords and battens). In this case, it is expected that the batten column will have different behavior and failure modes. If the lateral load or displacement is due to seismic actions, more complexities will exist in the column behavior due to nonlinearities and its post-failure response. Few researches were reported about the behavior of batten columns in seismic conditions and their ductility. In this research, the backbone curves for batten columns have been also developed based on their cyclic response. The component backbone curve represents the nonlinear behavior of component in plastic hinge locations and was used in the nonlinear pushover analysis. The backbone curve for some structural components has been found in many standard and guidelines of seismic evaluation like as FEMA356. Using the backbone curve, the available ductility of column considering its post failure response under cyclic lateral loads, could be evaluated. The backbone curve for batten columns does not exist in any guideline or research reports. Because of differences between behavior and failure modes of batten and solid web columns under seismic action, it was expected that their backbone curves had been substantially different. In this research, cyclic response of batten columns with different geometries have been investigated subjected to cyclic lateral and 3 level of constant axial load. Using cyclic curves, the backbone curves of considered batten columns have been developed. The results show that the available ductility of batten columns is considerably low compared with solid web columns. The failure mode of batten columns is local buckling of bottom chords (in flanges and web) in combination with overall buckling of these chords symmetrically. It is also shown that the backbone curves of batten columns are different from solid web columns. The backbone curves of batten columns are semi-ductile (Type 2) based on FEMA356 classification and don’t have any residual strength. Finally, a conservative backbone curve has been proposed for engineering applications.}, Keywords = {Batten Column,Backbone curve,Cyclic Response,pushover analysis,Seismic Vulnerability}, volume = {14}, Number = {4}, pages = {11-22}, publisher = {Tarbiat Modares University}, title_fa = {رفتار چرخه ای ستونهای مرکب با بست افقی و منحنیهای رفتاری آنها}, abstract_fa ={ در این مقاله، رفتار ستون‌های مرکب با بست افقی تحت اثر بارهای محوری ثابت و جانبی چرخه‌ای مورد بررسی قرار گرفته و منحنی‌های رفتاری آن‌ها نیز استخراج و ارائه شده‌اند. منحنی‌های رفتاری اعضای سازه‌ای، بیانگر رابطه نیرو-تغییرمکان اعضاء تحت بارهای چرخه‌ای در محل تشکیل مفاصل پلاستیک است. این منحنی‌ها دارای کاربردهای گسترده در تحلیل‌های استاتیکی غیرخطی سازه‌ها به منظور انجام طراحی لرزه‌ای بر اساس عملکرد و یا انجام مطالعات ارزیابی و بهسازی لرزه‌ای است. در حال حاضر منحنی‌های رفتاری برای ستون‌های مرکب با بست افقی در دستورالعمل‌های ارزیابی لرزه‌ای سازه‌ها، موجود نیست. با توجه به تفاوت‌های موجود در رفتار لرزه‌ای، حالات شکست و شکل‌پذیری میان ستون‌های مرکب و توپر، استفاده از منحنی‌های رفتاری ستون‌های توپر برای ستون‌های مرکب صحیح نیست. در پژوهش حاضر، منحنی‌های چرخه‌ای تحت بارهای جانبی برای ستون‌های مرکب با شرایط مختلف هندسی، با استفاده از تحلیل‌های اجزاء محدود غیرخطی، به دست آمده و با استفاده از آن‌ها، منحنی‌های رفتاری این ستون‌ها تهیه شده و بررسی شده است. در پایان بر اساس نتایج به دست آمده، یک منحنی رفتاری پیشنهادی برای ستون‌های مرکب با بست افقی برای استفاده در موارد کاربردی ارائه شده است.}, keywords_fa = {ستون مرکب با بست افقی,منحنی رفتاری,رفتار چرخه ای,تحلیل استاتیکی غیر خطی,آسیب پذیری لرزه ای}, url = {http://mcej.modares.ac.ir/article-16-3750-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-3750-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Raphiey, Masoud 1 and Ghodsian, Masoud 2 and Dehghani3, ٭ Amir Ahm}, title = {Intelligent hydraulic deign of tunnel type sediment excluders}, abstract ={The sediment excluders are provided on the barrages or diversion weirs in the river pocket adjacent to the head regulator to minimize sediment entry in to the canal water. On rivers, the excluders have to deal with alluvial material being transportd by the river. Excessive sediment load can cause damage in a variety of ways which result in many serious problems such as meandering of stream, reduction of channel capacity, silting up of canal, damage to power units and obstruction to navigation. Different types of sediment extractors/ excluders, such as tunnel type, vortex tubes, rectangular settling basins and vortex type settling basins are ofthen employed for this purpose. A tunnel-type sediment excluder is commonly used at the headwork of a canal for preventing excess sediment entry in to the off-taking canal. In such type of excluders, the sediment-laden water, which flows mainly near the bed, is made to flow through the tunnels provided at the bed and the sediment-free water in the top layers is allowed to enter the off-taking canal. It may be then discharged back into the river downstream through the undersluice bays. Comparatively sediment-free water in the top layers is allowed to enter the canal. The only hydraulic principle utilized in its design is that energy loss is kept to a minimum and a minimum velocity of flow is ensured through the tunnel for the non-deposition of the coarse material  In the method recommended by Garde and Pande (1976) and Kothyari (1999) for design of tunnel-type sediment excluders, the main objective is to design a tunnel which is able to flush maximum of sediment load through the tunnel by minimum of excluder discharge and minimum of blockage hence considering all restrictions and constraints for design of such structures.         In the current research it was tried to achieve an optimum design using fuzzy logic abilities and searching the solution domain by an intelligent search method (Genetic Algorithm) which is able to pass the local optimums and find the global optimum. GA considers many points in the serach space simultaneously and has been found to provide a rapid convergence to a near optimum solution in many types of problems. Then optimal designs of GA and Direct-Search method were compared with some of projects in India (i.e. Ganga, Sarda and Eastern Kasi) which were design using traditional methods. A fuzzy AHP (Analytic Hierarchy Process) approach was used for assessing the weight of efficiency, blockage and sediment excluder discharge in goal function. AHP is particulary usefull for evaluating complex multi attribute alternatives involving subjective criteria.The fuzzy AHP approach allows a more accurate description of the decision making process. The triangular fuzzy numbers were used to build the comparision matrices of AHP based on pairwise comparision technique.The results show that the Genetic Algorithm method gives better results in compare with direct search technique. The result also show that the efficiency of tunnel-type sediment excluders are high enough in both optimal design and traditional methods, but sediment blockage percent in propose optimal design is less than correspond design values using}, Keywords = {: Hydraulic design,Sediment excluder,Genetic algorithm,Fuzzy Logic}, volume = {14}, Number = {4}, pages = {23-37}, publisher = {Tarbiat Modares University}, title_fa = {طراحی هیدرولیکی هوشمند تونل‌های رسوب‌گیر رودخانه‌ای}, abstract_fa ={در طراحی تونل­های رسوب‌گیر بیشتر هدف، دستیابی به طرحی است که علاوه بر رعایت کامل محدودیت­ها و ملاحظات طراحی، بتواند با کمینه دبی عبوری از رسوب‌گیر، بیشترین رسوب را با کمینه گرفتگی، از تونل عبور دهد. در این پژوهش با استفاده از دیدگاه منطق فازی، اهمیت، وزن معیار­ها و شاخص­های سنجش طرح در انتخاب طرح بهینه تونل­های رسوبگیر لحاظ شد. همچنین با استفاده از یک روش جستجوی هوشمند و دارای قابلیت عبور از مینیمم­های محلی احتمالی، فضای حل مساله مورد جستجو قرار­گرفت. سپس تونل­های رسوب‌گیر طراحی شده با روش جدید، با طرح­های موجود و همچنین با نتایج حاصل از به کارگیری روش جستجوی مستقیم (Direct search) که از جمله ابزار­های نرم­افزار MATLAB است مقایسه شد. طراحی­های به دست آمده با روش طراحی ارائه شده، وضعیت بهتری را در مقایسه با طراحی‌های موجود نشان می­دهند.}, keywords_fa = {طراحی هیدرولیکی,تونل رسوبگیر,الگوریتم ژنتیکی,منطق فازی}, url = {http://mcej.modares.ac.ir/article-16-2454-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2454-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Zahrai, Seyed Mehdi and ArmanNikoo, Sobh}, title = {Comparing Seismic Performance of Yielding Damped Braced Frames with Mild and Low-Yield Steel in Typical Steel Buildings}, abstract ={مقایسه عملکرد لرزه ای میراگرهای تسلیمی مرکزی از فولاد ساختمانی و فولاد با حد جاری شدن پایین در ساختمانهای فولادی متداول سید مهدی زهرائی دانشیار قطب علمی مهندسی و مدیریت زیرساختهای عمرانی، دانشکده عمران دانشگاه تهران mzahrai@ut.ac.ir سبحان آرمان نیکو کارشناس ارشد مهندسی زلزله- پژوهشکده ساختمان و مسکن sobhan.arman@gmail.com در این تحقیق به مقایسه عملکرد لرزه ای میراگرهای تسلیمی مرکزی با درصد بازشوی 20 تا 30%، از فولاد ساختمانی و فولاد با حد جاری شدن پایین در ساختمانهای فولادی متداول پرداخته شده است. بدین منظور قابهای یک طبقه با استفاده از نرم افزار ANSYS تحت تحلیل قرار گرفته اند و با استفاده و استناد به نتایج حاصله ابتدا همین سازه ها با مقاطع و هندسه مشابه در نرم افزار SAP2000 مدلسازی شده و پس از مطابقت نتایج، مدلهای قابهای فولادی 5 و 7 طبقه در نرم افزار SAP2000 به روش تحلیل بار افزون تحت تحلیل قرار گرفته اند. نتایج به دست آمده نشان دهنده بهبود رفتار لرزه ای این قابها در صورت استفاده از فولاد با حد جاری شدن پایین به جای فولاد معمولی در سیستم قاب مرکزی می باشد. افزایش سختی قاب با میراگر حداقل به میزان 5/1 برابر، کاهش تغییرمکان حد تسلیم حداقل به میزان 50 درصد، بهبود منحنی های هیسترزیس و همچنین تشکیل عمده مفاصل پلاستیک بر روی اعضا میراگر تسلیمی مرکزی ازجمله نتایج بدست آمده می باشد. کلید واژه ها: میراگر تسلیمی مرکزی، فولاد ساختمانی، فولاد با حد جاری شدن پایین، منحنی هیسترزیس، مفصل پلاستیک. Comparing Seismic Performance of Yielding Damped Braced Frames with Mild and Low-Yield Steel in Typical Steel Buildings Seyed Mehdi Zahrai Associate Professor, Center of Excellence for Engineering and Management of Civil Infrastructures, School of Civil Engineering, the University of Tehran, mzahrai@ut.ac.ir Sobhan arman nikoo M.Sc. in Earthquake Engineering, Building and Housing Research Center, sobhan.arman@gmail.com In this paper, the seismic performance of typical steel buildings with yielding damped braced frames of mild steel (MS) and 20-30% opening is compared to that having low yield steel (LYS). For this purpose, one story frames are first modeled by "ANSYS" software, then calibrating the results, these structures are carefully modeled with the same geometry and section using "SAP2000" software. Using the validated models, five and seven story frames are analyzed by the push over method in "SAP2000" software. The results demonstrate that the seismic response of these frames improves if low yield steel instead of mild steel is used in central frame system. The results for the frame with damper included: stiffness increase minimum 1.5 times, at least 50% reduction of yielding point displacement, hysteretic curves improvement and formation of the main plastic hinges on the members of the yielding damped braced frames. Key words Yielding Damped Braced Frames, Low Yield Steel, Mild Steel, Hysteretic Curve, Plastic Hinge.}, Keywords = {Yielding Damped Braced Frames,Low Yield Steel,Mild Steel,Hysteretic Curve,Plastic Hinge}, volume = {14}, Number = {4}, pages = {39-52}, publisher = {Tarbiat Modares University}, title_fa = {مقایسه عملکرد لرزه ای میراگرهای تسلیمی مرکزی از فولاد ساختمانی و فولاد با حد جاری شدن پایین در ساختمانهای فولادی متداول}, abstract_fa ={در این تحقیق به مقایسه عملکرد لرزه ای میراگرهای تسلیمی مرکزی با درصد بازشوی 20 تا 30%، از فولاد ساختمانی و فولاد با حد جاری شدن پایین در ساختمانهای فولادی متداول پرداخته شده است. بدین منظور قابهای یک طبقه با استفاده از نرم افزار ANSYS تحت تحلیل قرار گرفته اند و با استفاده و استناد به نتایج حاصله ابتدا همین سازه ها با مقاطع و هندسه مشابه در نرم افزار SAP2000 مدلسازی شده و پس از مطابقت نتایج، مدلهای قابهای فولادی 5 و 7 طبقه در نرم افزار SAP2000 به روش تحلیل بار افزون تحت تحلیل قرار گرفته اند. نتایج به دست آمده نشان دهنده بهبود رفتار لرزه ای این قابها در صورت استفاده از فولاد با حد جاری شدن پایین به جای فولاد معمولی در سیستم قاب مرکزی می باشد. افزایش سختی قاب با میراگر حداقل به میزان 5/1 برابر، کاهش تغییرمکان حد تسلیم حداقل به میزان 50 درصد، بهبود منحنی های هیسترزیس و همچنین تشکیل عمده مفاصل پلاستیک بر روی اعضا میراگر تسلیمی مرکزی ازجمله نتایج بدست آمده می باشد.}, keywords_fa = {میراگر تسلیمی مرکزی,فولاد ساختمانی,فولاد با حد جاری شدن پایین,منحنی هیسترزیس,مفصل پلاستیک}, url = {http://mcej.modares.ac.ir/article-16-10266-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-10266-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {ShahidiImamjomeh, Farhood and Rezaeian, Alireza and Jamal-Omidi, Majid and ShahidiImamjomeh, Farh}, title = {Evaluation of non-linear cyclic behavior of CONXL moment connection with different detail in the column and optimizing the arrangement of bolts}, abstract ={Box-columns are suitable members for structures with moment frames in two directions but performing the internal continuity plate in them causes some practical troubles. Details of the new proposal to alleviate this problem in box-columns is CONXL connection. This connection includes a set of Collar Flange Top (CFT), Collar Flange Bottom (CFB), Collar Corner Top (CCT), Collar Corner Bottom (CCB) and when the depth of the beams is more than 460 mm, Collar Corner Middle (CCM), Collar Web Extension (CWX) (only in the face of beam to column connection) and also a set of diagonal pre-tensioned high strength bolts (45 degrees angle), which collectively make up CONXL node. The bolts and collars performance make up a rigid diaphragm around the column. All collar flanges top and bottom are connected to the beam by means of groove welding with complete joint penetration, and the connection of collar web extension to the beams and that of collars corner to the column walls is made by fillet weld; collar corners are connected to each other through groove weld in factory and the pieces are just assembled in worksite. The objectives of presenting these details are industrializing, removing weld in workplace, removing continuity plate, enhancing quality, speeding up the construction, and simplifying the inspection. Through the distribution of force among collar systems, forces are transmitted from beams to the columns. The aim of this study is to numerically study the seismic behavior of CONXL connection without filler concrete of columns and to reduce the number of collar bolts with different arrangements. In order to reach this purpose, the numerical results of specimens; RBS and Kaiser bolted bracket (KBB) connection are compared to experimental results to verify the modeling and analyzing and good agreement is observed between numerical and experimental data. Afterward nine specimens of CONXL moment connections in box-columns not filled with concrete whit axial force in single, planer and bi-axial loading conditions with different arrangement of bolts are studied and their performances are evaluated. Results showed that seismic behavior of specimens with beam section depths equal or less than W30 series under cyclic loading, even with reducing the number of bolts to 16 numbers, is suitable in the over 0.04 radian rotations. Also, use of 16 numbers of bolts in connections with W30 series of beams, when it would be appropriate that use for corner connections (Single sided loading), and the specifications of ASTM-A36 for beams material to be used. Also, whatever the position of bolts to be outer than in collar flanges, axial strain in the bolts shank is bigger and its slip is less. The optimal position of the bolts is near the middle of the collar flanges. The results also showed that seismic behavior of all specimens with columns without concrete filling is appropriate and the column will remain without any remarkable local buckling in over 0.04 radian inter-story drift angle.}, Keywords = {CONXL moment connection,Seismic behavior,Bolt,Box-column,Collar system}, volume = {14}, Number = {4}, pages = {53-65}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی رفتار غیرخطی چرخه ای اتصال خمشیCONXL با تغییر در جزئیات ستون و بهینه کردن آرایش پیچ ها}, abstract_fa ={اتصال CONXL یکی از اتصالات جدید ریخته گری شده در ستون های قوطی می باشد. هدف از این مقاله بررسی لرزه ای جزییات جدیدی از این اتصال بصورت عددی می باشد. برای این هدف، ابتدا به منظور صحت سنجی مدلسازی عددی و آنالیز، دو نمونه اتصال خمشی، شامل یک نمونه اتصال خمشی RBS و یک نمونه اتصال خمشی ریخته گری شده براکت پیچی کایزر (KBB) به صورت عددی مدل و صحت و دقت نتایج آن با نتایج آزمایشگاهی مقایسه گردید. سپس رفتار لرزه ای اتصال خمشی CONXL در ستونهای قوطی بدون بتن پرکننده و ورق پیوستگی همراه با نیروی محوری ستون در 9 نمونه دارای 32 و 16 عدد پیچ با تغییر آرایش موقعیت قرارگیری آنها تحت بارگذاری یکطرفه، دوطرفه و دو محوره (سه بعدی) به صورت چرخه ای بررسی گردید. نتایج نشان داد که رفتار لرزه ای ستون در تمامی نمونه ها مطلوب است بخصوص برای ستونهای گوشه و همچنین، استفاده از 16 عدد پیچ در اتصالات مقاطع W30 ، زمانی مناسب خواهد بود که از آن در اتصالات گوشه (دارای بارگذاری یکطرفه) و از مشخصات مصالح ASTM-A36 برای تیرها استفاده شود. همچنین موقیت قرارگیری پیچ ها هرچه به سمت بیرون یقه بال ها نزدیکتر باشد کرنش محوری میله پیچ ها بیشتر ولی لغزش آن کمتر میشود. بهینه ترین حالت برای موقعیت پیچ نقطه ای نزدیک به وسط یقه بال خواهد بود.}, keywords_fa = {اتصال خمشی CONXL,رفتار لرزه ای,پیچ های پر مقاومت,ستون قوطی,سیستم یقه}, url = {http://mcej.modares.ac.ir/article-16-6545-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6545-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {sadighihashtchin, rez}, title = {Numerical Evaluation of the Effect of Vertical Component of Near-Field Earthquakes on the Dynamic Behavior of Embankment Dams, A Case Study: Alborz Dam}, abstract ={Most of the research has been concentrated on the effects of the horizontal components of near-field earthquakes on the dynamic behavior of the embankment dams. In this paper, the effects of the vertical components will be considered. One of the important characteristics of the near-field ground motions, is the noticeable vertical component with the high frequency content that can exceed considerably, in many cases, the horizontal component of the same earthquake. So far, few studies have been done in this area. In order to investigate the effect of the vertical ground motion on the dynamic behavior of embankment dams, a two dimensional numerical model of the Alborz dam is analyzed by using finite difference method which is used in FLAC2D code. It should be noted that the Alborz dam is a rockfill type with clay core and a maximum height of 78 m located on the Babol River in the north of Iran. The Mohr Coulomb elastic perfectly plastic constitutive model was used to simulate the stress-strain behavior of the dam body and its foundation during the static and dynamic loading. Steps of modeling are as follow: At first stage, construction was carried out in 16 layers. At this step, coupling analysis were done in order to simulate the consolidation and build up of pore pressure in clayey core, with respect to the real time of construction for each layer. Then the analyses were continued to modeling of the impounding. So at this stage the reservoir was raised to the normal water level and the model were analyzed to the steady state seepage condition. Records of near-field and far-field were selected from the same earthquake to provide better and more accurate comparison. Before applying the earthquake records to the base of the foundation in the model, they must be modified. So deconvolution analyses were done by using SHAKE2000 code in order to get the target motion with peak ground acceleration of 0.52g at the surface of the foundation (maximum credible earthquake level at the site of Alborz dam). In addition filtering process, baseline correction and conversion the acceleration time history to the stress time history were done. Results of analysis show that the vertical component of near-field ground motion has considerable effect on the magnitude of strains and deformations including: increasing the settlement of the dam crest to about 45 percent, increasing the deformation of the horizontal axis of the dam, reduction of the magnification factor of the dam crest and especially in the case of near-fault, which the occurrence of near-field earthquakes is more probable. Therefore, this issue should be considered in locating the embankment dams regarding the seismic potential and the distance from the fault, and in the design of them.}, Keywords = {Vertical component of earthquakes,Dynamic Analysis,Embankment dams,finite difference method,Near-field earthquake}, volume = {14}, Number = {4}, pages = {67-79}, publisher = {Tarbiat Modares University}, title_fa = {بررسی عددی اثر مولفه قائم زلزله های حوزه نزدیک بر رفتار دینامیکی سدهای خاکی ، مطالعه موردی سد البرز}, abstract_fa ={ در این مقاله اثر مولفه قائم زلزله‌های حوزه نزدیک بر رفتار دینامیکی سدهای خاکی مطالعه و ارزیابی می‌شود. بیشتر پژوهش‌های انجام شده در رابطه با تاثیر زلزله‌های حوزه نزدیک بر رفتار دینامیکی سدهای خاکی، شامل اثر مولفه افقی آن‌ها است. یکی از ویژگی‌های مهم زلزله‌های حوزه نزدیک، دارا بودن مولفه قائم قابل توجه با محتوای فرکانسی بالاست که در بسیاری از موارد از مولفه افقی همان زلزله به مقدار قابل توجهی تجاوز می‌کند. تاکنون مطالعات کمی در این زمینه صورت گرفته است. برای بررسی اثر مولفه قائم زلزله‌های حوزه نزدیک بر رفتار دینامیکی سدهای خاکی، مدلی دو بعدی از سد البرز به روش تفاضل محدود و با کمک نرم‌افزار FLAC 2D در نظر گرفته شد. در این مطالعه شتاب نگاشت‌های حوزه نزدیک و دور از یک زلزله انتخاب شد تا امکان مقایسه بهتر و دقیق‌تر فراهم شود. نتایج تحلیل‌ها بیانگر اثر قابل توجه مولفه قائم زلزله‌های حوزه نزدیک بر رفتار دینامیکی سدهای خاکی شامل افزایش نشست تاج سد تا حدود 45 درصد، افزایش تغییر شکل های افقی محور سد، کاهش ضریب بزرگ‌نمایی تاج سد و همچنین لزوم توجه به اثر مولفه قائم زلزله، به ویژه در نواحی نزدیک به گسل که احتمال وقوع زلزله‌های حوزه نزدیک وجود دارد، است، که این مسئله باید در جانمایی سدهای خاکی به لحاظ توان لرزه‌ای و فاصله از گسل‌های موجود در منطقه و همچنین در طراحی آنها در نظر گرفته شود.}, keywords_fa = {مولفه قائم زلزله,تحلیل دینامیکی,سدهای خاکی,روش تفاضل محدود,زلزله حوزه نزدیک}, url = {http://mcej.modares.ac.ir/article-16-7407-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7407-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Abbasian, MohammadSadegh and Jalali, Soheil}, title = {Multivariate Flood Frequency Analysis Using Copula with Parametric and Nonparametric Marginal Distribution Function}, abstract ={Many variables under study in hydrology are continuous and random; hence, it necessitates using probability and statistics sciences to study them. In a specific classification, variables are categorized to be either explanatory or response variable. An explanatory variable is defined as a variable which explains or predicts changes in the value of another variable, while a response variable is a variable whose prediction of its changes is desired under the effect of other variables. Due to the mentioned definition, a response variable may depend on one or more explanatory variables. Therefore, in the first case the response variable is intrinsically univariate and in the second case is intrinsically multivariate. If it is known that a hydrological response variable is intrinsically multivariate, multivariate statistical approaches must be employed, especially in the case of dependency among explanatory variables, because it has been widely warned that implementing univariate statistical approaches may result in over/under estimations. According to the fact that flood is an intrinsically multivariate event, it is essential to employ multivariate approaches to analyze it. The most important characteristics of flood are peak discharge, volume and duration. A traditional approach in multivariate analyses is to use classical multivariate distribution functions with parametric marginal distribution functions. However, both classical multivariate distribution functions and parametric distribution functions face substantial limitations. Among the limitations attributed to classical multivariate distribution functions, one may refer to the necessity of identifying marginal distribution functions and their parameters and equality of the kind of marginal distribution functions as the most important limitations. Also in the use of parametric distribution functions for marginal variables, an assumed distribution function is used to describe the distribution of data, while perhaps the assumed distribution function does not accurately describe the real distribution of data. The aim of this article is to establish joint distributions of different combinations of flood characteristics and corresponding return periods. Hence, firstly marginal distribution functions are chosen among parametric distribution functions and non-parametric distribution functions, which are not restricted to estimation of some parameters. Then joint analyses of flood variables are performed using copulas, which do not confront limitations of classical multivariate distributions. Finally, having found and appropriate copula for each combination of flood characteristics, joint return periods are calculated and contour plot of joint return periods are plotted. Joint return periods of flood characteristics can be used by water resources decision makers and engineers as a hydraulic design criterion and provide useful information for risk analysis. In this article, joint analyses of flood variables are performed using copulas, which do not confront limitations of classical multivariate distributions, such that marginal distribution functions are chosen among parametric distribution functions and non-parametric distribution functions, which are not restricted to estimation of some parameters. It should be mentioned that the R language has been utilized as the primary tool in order to perform calculations and draw diagrams. Keywords: Flood Frequency Analysis, Joint Return Periods, Copula, Non-parametric distribution}, Keywords = {Flood Frequency Analysis,Joint Return Periods,Copula,Non-parametric distribution}, volume = {14}, Number = {4}, pages = {81-92}, publisher = {Tarbiat Modares University}, title_fa = {تحلیل فراوانی چندمتغیره سیلاب با استفاده از تابع مفصل و توزیع‌های حاشیه‌ای پارامتری و ناپارامتری}, abstract_fa ={ از آن‌جایی که سیلاب پدیده‌ای چندمتغیره است، اتخاذ رویکردهای چند متغیره در تحلیل آن ضروری است. روش سنتی انجام تحلیل‌های چندمتغیره، استفاده از توزیع‌های چندمتغیره کلاسیک با توابع حاشیه‌ای پارامتری است. این در حالی است که هم استفاده از توزیع‌های چندمتغیره کلاسیک و هم استفاده از توزیع‌های پارامتری با محدودیت‌های جدی مواجه است. از مهم‌ترین محدودیت‌‌های توزیع‌های چندمتغیره کلاسیک می‌توان به لزوم مشخص بودن توابع توزیع حاشیه‌ای و پارامترهای آنها و یکسان بودن توابع توزیع حاشیه‌ای اشاره کرد. همچنین در استفاده از توزیع‌های پارامتری برای متغیرهای حاشیه‌ای از یک توزیع‌ پیش‌فرض برای تفسیر توزیع داده‌ها استفاده می‌شود، در حالی که ممکن است توزیع فرض شده به‌خوبی توزیع واقعی داده‌ها را توصیف نکند. در مقاله حاضر تحلیل‌های توأم متغیرهای سیلاب با استفاده از توابع مفصل که محدودیت توزیع‌های چندمتغیره کلاسیک را ندارند انجام گرفته، به‌‌گونه‌ای که توزیع‌های حاشیه‌ای از میان توزیع‌های پارامتری و توزیع‌های ناپارامتری که بی‌نیاز از برآورد تعدادی پارامتر است برگزیده شده‌اند. واژگان‌کلیدی-تحلیل فراوانی سیلاب، دوره بازگشت‌ توأم، تابع مفصل، توزیع ناپارامتری}, keywords_fa = {تحلیل فراوانی سیلاب,دوره بازگشت‌ توأم,تابع مفصل,توزیع ناپارامتری}, url = {http://mcej.modares.ac.ir/article-16-10840-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-10840-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Shoormeij, Ebrahim and Fakhri, Mansor}, title = {Technical and economic evaluation of pavement rehabilitation on vehicle fuel consumption costs}, abstract ={Evaluation of Vehicle Operating Costs (VOC) are necessary in pavement management. Vehicle Operating Costs including Fuel consumption costs, accident costs, oil consumption costs, maintenance costs and vehicle depreciation that often paid by road users. Vehicle Fuel consumption costs, is one of the important components of the life cycle costs analysis that it is typically between 20 to 40 percent of the total vehicle operating costs. There are many factors that effect on vehicles fuel consumption. Vehicle type, pavement surface condition, road geometry, vehicle speed and,…effect on vehicle fuel consumption and pavement life cycle costs. Pavement surface condition is one of the factors that effected on vehicle fuel consumption. Pavement roughness, skid resistance and the pavement deterioration are the components of the pavement surface condition. Using of pavement maintenance alternatives at the appropriate time, in addition to improve the pavement surface condition, reduce the vehicle operating costs and vehicle fuel consumptions. The goal of this research is to evaluate the effect of pavement maintenance in a 10 years analysis period on vehicle fuel consumption costs using HDM-4 software. HDM-4 is an application software for pavement management and evaluation of pavement surface condition that has been developed by the world bank. This software needed a serious of input data to analysis. This input data are divided in to four parts, including road networks, vehicle fleets, road works (repair and rehabilitation standards), and HDM-4 Configuring (define standards criteria for each of the variables in the program). For this purpose, effect of pavement maintanence and rehabilitation evaluated in 1170 km of Khozestan province road networks. This rehabilitation alternatives including routine maintenance, single surface dressing, 50 mm overlay, 100 mm overlay and, pavement reconstruction. In this research each rehabilitation approaches was used Separately as a pavement maintenance alternative. In rehabilitation approaches it was supposed that after performed pavement rehabilitation IRI reached to 1.5 m/km. According to HDM-4 ranking this IRI is good. Results of this research showed that, pavement surface conditions effect on vehicle fuel consumption. In other words, improving pavement surface condition cause to reduced vehicle fuel consumption. With applying routine maintenance (crack sealing and patching) there was no change on reducing the vehicle fuel consumption. But, with applying single surface dressing vehicle fuel consumption was reduced during the pavement analysis period. The reduction in vehicle fuel consumption after applying pavement rehabilitation is varies for different type of vehicles. Although the costs of rehabilitation alternatives are more than the cost of routine maintenance, but the economic savings in reduction of vehicle fuel consumption costs are more than the costs of the pavement rehabilitation alternatives in the long terms analysis. According to the result, economic saving from the single surface dressing alternative is more than the other pavement maintenance and rehabilitations alternatives. It was concluded that using rehabilitation in the appropriate time could cause reduction in fuel consumption and resulted in cost saving.}, Keywords = {"HDM-4","Fuel consumption","Pavement surface condition","pavement rehabilitation","HDM-4"}, volume = {14}, Number = {4}, pages = {93-102}, publisher = {Tarbiat Modares University}, title_fa = {بررسی فنی و اقتصادی رویکردهای مرمت و بهسازی روسازی بر مصرف سوخت وسایل نقلیه}, abstract_fa ={ مصرف سوخت وسایل نقلیه، یکی از پارامترهای مهم در تحلیل هزینه‌های چرخه عمر روسازی است. عواملی مانند نوع وسیله نقلیه، وضعیت سطحی روسازی و... بر مصرف سوخت و هزینه‌های چرخه عمر روسازی تاثیرگذار است. هدف از این پژوهش، بررسی تاثیر رویکردهای مختلف نگه‌داری و بهسازی روسازی در دوره تحلیل ده سال، بر مصرف سوخت و هزینه‌های مصرف سوخت وسایل نقلیه با استفاده از نرم‌افزار HDM-4 است. به این منظور تاثیر رویکردهای مرمت و بهسازی بر هزینه‌های مصرف سوخت وسایل نقلیه در 1170 کیلومتر از راه‌های شریانی استان خوزستان، ارزیابی شد. در این پژوهش هر یک از رویکردهای مرمت و نگه‌داری روسازی، به صورت جداگانه به عنوان رویکرد نگه‌داری، در دوره طرح، مورد تحلیل و ارزیابی قرار گرفتند. در رویکرد نگه‌داری اساسی، فرض شد پس از اجرای عملیات بهسازی، مقدار IRI به 5/1 متر بر کیلومتر برسد که مطابق رده‌بندی HDM-4 در محدوده خوب قرار دارد. با توجه به نتایج، با در نظر گرفتن نگه‌داری روزمره(درزگیری و لکه‌گیری)، تغییری در کاهش مصرف سوخت وسایل نقلیه مشاهده نشد. ولی با اعمال نگه‌داری اساسی، مصرف سوخت وسایل نقلیه در دوره طرح روسازی کم شد. نتایج این پژوهش نشان می‌دهد که با اجرای نگه‌داری اساسی در زمان مناسب، صرفه‌جویی زیادی در مصرف سوخت وسایل نقلیه به دست می‌آید..}, keywords_fa = {"مصرف سوخت","وضعیت سطحی روسازی","مرمت و بهسازی روسازی"}, url = {http://mcej.modares.ac.ir/article-16-2798-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2798-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {ZareHosseinZadeh, Ali and SeyedRazzaghi, Seyed Ali}, title = {Damage Detection in Beams Using Static Deflection measurements and Statistical Hypothesis Testing}, abstract ={Building structures begin to deteriorate once they are built due to harsh environment such as earthquake. To inspect present buildings and bridges following major disastrous events, such as earthquakes and hurricanes is often time-consuming and of high expense. This is also the case in regular operating conditions. Indeed critical members and connections are hidden under cladding and other architectural surface covers. This study aims to propose a novel method for identification of damages occurred in beams based on deflection under static loading. In this paper damage location on a beam is determined using statistical hypothesis testing applied on the deflection of the beam. It is worth mentioning that the statistical hypothesis testing is an appropriate method for statistical inference which can be used to judge a claim concerning an event in regards to different scenarios and possibilities. The statistical claim which would be analyzed is that damage is present among elements of the beam. Deflection of beam as a derivation of stiffness will be utilized here. Hence the basic idea in this study; to locate damages, is behind of calculating the difference between measured and estimated deflection of nodes of each element in both intact and damaged structures. Elements damage can be specified by applying damage index which is defined as D(x). Element’s damages can be judged through the damage index sign in two nodes of every element: The element will be considered damaged if the index is positive for both nodes of middle element or it is positive in only one node of element leading edges of fulcrums. To illustrate the efficiency and robustness of proposed method three different examples are considered. First example is a simple beam with five different scenarios including single and multiple damages. Second example is also presented to show comparison of the proposed method with the study by Abdo [18] and finally third instant is considered for showing reliability of the method in different beam types. For all of the examples, the deflection of damaged beams is recorded via sensors under only one state of static loading and the statistical parameters of the undamaged beams are generated under several static loading. Then by calculation of damage index, we can decide about damage locations. All examples show good performance of the novel method in damage localization. The most important result obtained from these examples is that, the more fine mesh, the better and the more accurate performance of the method. Of course this assertion is more important in the elements leading edges of fulcrums. Further, the performance of this method is demonstrated through damage simulation where the measured data are contaminated with noise and hence to evaluate the stability of the proposed method against various noise levels, scenarios are considered with different such levels.}, Keywords = {Static Deflection,damage detection method,Damage,statistical hypothesis,statistical hypothesis testing}, volume = {14}, Number = {4}, pages = {103-113}, publisher = {Tarbiat Modares University}, title_fa = {تشخیص آسیب در تیرها با کمک اندازه گیری خیز استاتیکی و آزمون فرض آماری}, abstract_fa ={تشخیص آسیب های ایجاد شده در اعضای ساختمانی از اهمیت بسیار زیادی برخوردار است. در این مقاله، روشی جدید جهت تشخیص آسیب های رخ داده در تیرها، با کمک جابجایی تیر در اثر اعمال بار استاتیکی (خیز)، ارائه شده است. برای این منظور، جابجایی تیر، در اثر اعمال بار استاتیکی تعیین شده و با کمک آزمون فرض آماری، محل آسیب رخ داده در تیر مشخص شده است. گفتنی است که آزمون فرض آماری، جزء روش های مناسب استنباط آماری بوده و می تواند در مورد ادعای مطروحه پیرامون یک قضیه، با بررسی حالات مختلف و محتمل، اظهارنظر نماید. ادعای آماری مورد استفاده در این مقاله، وجود آسیب در یک المان از تیر می باشد که این ادعا تحت عنوان «فرض مقابل یا Alternative Hypothesis» در نظر گرفته می شود. در نهایت جهت بررسی کارایی روش پیشنهادی، سناریوهای خرابی مختلفی مورد بررسی قرار گرفته است. نتایج بدست آمده حاکی از آن است که با روش پیشنهاد شده، می توان محل آسیب در تیر را با دقت بسیار زیادی تعیین نمود. هم چنین نتایج بدست آمده، حاکی از حساسیت بسیار کم روش پیشنهادی به وجود نوفه های اتفاقی می باشد.}, keywords_fa = {خیز استاتیکی تیر,روش تشخیص آسیب,خرابی,فرض آماری,آزمون فرض آماری}, url = {http://mcej.modares.ac.ir/article-16-8209-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-8209-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {abdollahzadeh, davood and Gerami, Mohse}, title = {Demand and Capacity of Structural Elements for Steel Moment Resisting Frames in Near Field of Fault}, abstract ={Experiments from disaster earthquakes showed, from Forward directivity, Backward directivity and Filing step effects in near fault strong motion, Forward directivity has more severe effects on engineering structures. In near fault regions when rupture propagation of fault is toward to the construction site and velocity of strong motion waves is approximately equal to rupture propagation speed, the velocity time history record of ground that is normal to the fault surface has 1 to 3 long period pulses with high magnitude. This future causes to impose more demands of strength and ductility to structures located normal to the fault line in near field of fault. Also average amplitude of response spectrum of near fault earthquakes are about 1.1 to 2 times more than average response spectrum of regions located far from fault. To estimation of forward directivity effect on structural elements, in this study variation of demand and capacity of beams and columns of steel moment resisting frames are studied under effect of forward directivity with variation of models height. So the variation of strength and ductility demand of structure elements have been estimated under effect of forward directivity based on FEMA356 instruction by 100 time history nonlinear dynamic analyses for 5 structural models. The modes were steel moment resisting farms with 3, 5, 7, 10 and 15 stories height. To studding about effect of forward directivity on beams, maximum nodal rotation, maximum absolute moment and seismic performance of beams studied. Results showed forward directivity causes to increase nodal rotation 1.1 to 1.7 times more for low-rise models (7 stories and less) and 1.4 to 3.2 times more fore high-rise models. The maximum moment of beams is increased 2 to 16% for low-rise models and 10 to 50% for high-rise models. In life safety level, demand to capacity ratio of performance level of beams is increased between 1 to 1.6 times more for low-rise models and 1.2 to 3.2 times more for high-rise models. Also it has been indicated that forward directivity has not any effects on beams ductility. Studding on forward directivity effects on columns showed because of interaction between axial force and moment of columns, forward directivity is able to effect on moment capacity and ductility of columns. So forward directivity increases 2 to 20% axial force of columns related to height of models and location of columns. Results illustrate axial force increasing about 20% causes to decrease 12.5 to 50% of moment strength capacity of column and also it can decreases 20 to 50% rotation ductility of columns. On the other hand forward directivity causes to increase moment demand of columns about 30 to 56% for high-rise models. Conclusions showed forward directivity effects causes to increase demand to capacity ratio of structural elements about 1.1 to 1.75 times more for low raise models (7stories and less) and 1.5 to 5 times more for high rise models. Also it is considered that aspect ratio of structure has a direct relationship to amplification of forward directivity effect on columns.}, Keywords = {Earthquake effect,Rupture directivity,Seismic evaluation,ductility,Aspect Ratio}, volume = {14}, Number = {4}, pages = {115-125}, publisher = {Tarbiat Modares University}, title_fa = {نیاز و ظرفیت اجزای سازه ای قابهای خمشی فولادی در حوزه نزدیک گسل}, abstract_fa ={ در حوزه نزدیک گسل هنگامی که گسترش شکست گسل به سمت ساختگاه باشد و سرعت انتشار امواج زلزله با سرعت گسترش شکست گسل تقریبا یکسان شود، مولفه افقی عمود بر سطح شکست گسل برای نگاشت سرعت زلزله حاوی 1 تا 3 پالس با دامنه زیاد و دوره تناوب بالا است. که این مسئله منجر به تحمیل نیاز بیشتر مقاومتی و شکل پذیری به سازه در جهت عمود بر خط گسل می‌شود. در این مطالعه با انجام 100 تحلیل دینامیکی غیرخطی تحت نگاشت‌های حوزه دور و نزدیک گسل برای 5 مدل قاب خمشی فولادی با ارتفاع 3، 5، 7، 10 و 15 طبقه، تغییرات ظرفیت و نیاز مقاومتی و شکل پذیری اجزای سازه‌ای براساس نشریه FEMA356 در سطح عملکرد ایمنی جانی برای قاب‌های خمشی فولادی تحت اثر جهت پذیری پیشرونده تخمین زده شده است. نتایج نشان داد جهت پذیری پیشرونده باعث افزایش نسبت نیاز به ظرفیت اجزای سازه‌ای در حدود 1,1 تا 1,75 برابر در مدل‌های کوتاه مرتبه (کوتاه تر از 7 طبقه) و در حدود 1,5 تا 5 برابر در مدل‌های بلند مرتبه شده است.}, keywords_fa = {اثر زلزله,جهت پذیری شکست,ارزیابی لرزه ای,شکل پذیری,نسبت ارتفاع به عرض}, url = {http://mcej.modares.ac.ir/article-16-5025-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-5025-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Mosallanezhad, Mansour}, title = {A Numerical Study on Bearing Capacity of Ring and Circular Foundations on Granular Soils Reinforced by Grid-Anchor System}, abstract ={Abstract: Soil reinforcement is one of the soil improvement techniques. Over the last four decades, a large number of researches have been carried out in order to obtain the reinforcement type and the bearing capacity improvement of the reinforced soil. A new reinforcement type called Grid-Anchor (G-A) has been recently invented which is made of geogrids by adding polymer anchors to it. In this study the bearing capacity of ring and circular footings located on granular soils reinforced with the G-A is investigated using numerical analyses. Commercial finite-element software PLAXIS is employed to perform the simulations. The effect of depth of the first reinforcement layer, the vertical spacing, the number and width of reinforcement layers, the distance that anchors are effective, for each foundation were investigated. The effect of reinforcement stiffness for two types of footing has been investigated. A comparison between the results obtained for the G-A and geogrid reinforcement systems and unreinforced soils is demonstrated as well. Abstract: Soil reinforcement is one of the soil improvement techniques. Over the last four decades, a large number of researches have been carried out in order to obtain the reinforcement type and the bearing capacity improvement of the reinforced soil. A new reinforcement type called Grid-Anchor (G-A) has been recently invented which is made of geogrids by adding polymer anchors to it. In this study the bearing capacity of ring and circular footings located on granular soils reinforced with the G-A is investigated using numerical analyses. Commercial finite-element software PLAXIS is employed to perform the simulations. The effect of depth of the first reinforcement layer, the vertical spacing, the number and width of reinforcement layers, the distance that anchors are effective, for each foundation were investigated. The effect of reinforcement stiffness for two types of footing has been investigated. A comparison between the results obtained for the G-A and geogrid reinforcement systems and unreinforced soils is demonstrated as well. Abstract: Soil reinforcement is one of the soil improvement techniques. Over the last four decades, a large number of researches have been carried out in order to obtain the reinforcement type and the bearing capacity improvement of the reinforced soil. A new reinforcement type called Grid-Anchor (G-A) has been recently invented which is made of geogrids by adding polymer anchors to it. In this study the bearing capacity of ring and circular footings located on granular soils reinforced with the G-A is investigated using numerical analyses. Commercial finite-element software PLAXIS is employed to perform the simulations. The effect of depth of the first reinforcement layer, the vertical spacing, the number and width of reinforcement layers, the distance that anchors are effective, for each foundation were investigated. The effect of reinforcement stiffness for two types of footing has been investigated. A comparison between the results obtained for the G-A and geogrid reinforcement systems and unreinforced soils is demonstrated as well}, Keywords = {Ring Foundation,Circular Foundation,bearing capacity,Grid-Anchor (G-A),Reinforced soil}, volume = {14}, Number = {4}, pages = {127-136}, publisher = {Tarbiat Modares University}, title_fa = {مطالعه عددی افزایش ظرفیت باربری پی‌های حلقوی و دایره ای مستقر بر خاک های دانه ای مسلح شده توسط سامانه مهارشبکه}, abstract_fa ={ تسلیح خاک یکی از روش‌های بهبود خواص مکانیکی خاک است. پژوهش‌های زیادی طی چهار دهه اخیر به منظور تعیین نوع مسلح کننده و همچنین میزان افزایش ظرفیت باربری خاک مسلح شده با مسلح کننده‌ها انجام شده است. به تازه‌گی نوع جدیدی از مسلح کننده‌های پلیمری برای افزایش ظرفیت باربری خاک‌های دانه‌ای ابداع شده است. این سامانه جدید که مهارشبکه (G-A)نام‌گذاری شده است]1[، با تغییر ساختار ژئوگرید معمولی و اضافه کردن قلاب­های پلیمری به آن، ساخته می­شود. در این مقاله سعی شده است که با کمک تحلیل­های عددی، توان این نوع مسلح­کننده در افزایش ظرفیت باربری پی­های حلقوی و دایره­ای بررسی شد. عمق اولین لایه مسلح کننده، فاصله بین لایه‌ها، تعداد لایه‌ها، پهنای مسلح کننده و پهنای موثر قلاب‌گذاری در دو حالت پی حلقوی و دایره‌ای به گونه‌ای تعیین شده‌اند که شاهد بیشترین ظرفیت باربری باشیم. تاثیر سختی مسلح کننده در افزایش ظرفیت باربری در پی‌ها نیز مورد بررسی قرار گرفته‌اند. در پایان نتایج بدست آمده، با نتایج ظرفیت باربری پی واقع بر خاک ماسه­ای غیرمسلح و ماسه مسلح­شده با ژئوگرید معمولی مقایسه می­شوند.}, keywords_fa = {ظرفیت باربری,پی حلقوی,پی دایره ای,مهارشبکه,تحلیل عددی}, url = {http://mcej.modares.ac.ir/article-16-3870-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-3870-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {mirbaha, B. and saffar, m. and abrishame, s.a and sharafaty, S}, title = {Effect of Congestion Pricing on Users\' Mode Split Using Stated Preference Technique}, abstract ={Congestion pricing is one of the main strategies for demand management in urban areas. One of the main questions for decision makers, for implementing this strategy, is the effect of congestion pricing on users' mode split. For defining this, the willingness to pay of users should be estimated. In another word, we should know that how much users still will to pay for using their personal cars and how they intend to perform their mobility according to various prices. Previous studies had pay less attention to paratransit mode according to pricing. In this research, the effect of congestion pricing on users' mode choice has been investigated. The restricted traffic zone of Tehran has been selected for case study. Due to impossibility of direct observation, the stated preference method was applied for data gathering. Various pricing scenarios, based on experimental design concept, were defined and several types of questionnaires were designed. In these questionnaires, 3  types of data were asked from interviewees including trip chain of the users, socio economic characteristics and pricing scenarios. According to pricing scenarios, 4 choices including using personal car, public transportation, taxi and cancelling the trip were presented to users which they should choose only one option due to every pricing scenario. The reliability of questionnaires have been investigated with cronbach's alpha which results showed the proper reliability of questionnaires.  More than 3500 interviews were performed and after preliminary validation, were entered in the database. Based on this data, more than 70 variables were defined which their correlation was estimated and proper variables were chosen. For modeling, due to discrete nature of data, multinomial logit model was applied and calibrated for every choice.  In this regard, the feasibility of applying nested logit model was also tested which results showed the invalidity of this model. More than 200 models have been calibrated and finally best validated models have been chosen for describing the mode choice of every alternative. Results of modeling showed that having more expansive cars will increase the utility of using personal cars and reduce the public transport utilization. Also the residence location of the users is effective in their mode choice. Living in restricted zone, increase the willingness of users to use transit and paratransit mode. Users' education is also important in their choice. People with higher education level have more willingness to pay. The sensitivity analysis showed that pricing can be a proper tool for managing personal vehicles demand. When entrance toll is equal to 3000 tomans, only 35 percents use their personal vehicles. In this condition, 30 percents of users choose transit mode. Results also showed that choosing transit and paratransit mode is similar. When the toll is more than 17000 tomans, the rate of using taxi have higher growth comparing to transit utilization. Also, results showed that the demand for entering to restricted zone can be assumed inelastic. In highest toll, only 10 percents of users cancelled their trip. Finally, the sensitivity analysis for every mode has been accomplished and multiple future researches have been proposed. Keywords: Mode Split models, Congestion pricing, stated preference method}, Keywords = {}, volume = {14}, Number = {4}, pages = {137-148}, publisher = {Tarbiat Modares University}, title_fa = {بررسی تاثیر قیمت‌گذاری معابر بر شیوه انتخاب وسیله کاربران با استفاده از روش رجحان بیان شده}, abstract_fa ={قیمت­گذاری تراکم به عنوان یکی از مهمترین رویکردهای مدیریت تقاضا در معابر شهری مطرح می­باشد. یکی از سوالات اصلی تصمیم­گیران در ارتباط با بکارگیری این سیاست، میزان تاثیر قیمت­گذاری بر نحوه انتخاب وسیله افراد و مقدار تغییر از وسیله نقلیه شخصی به سایر شیوه­های جابجایی می­باشد. در این پژوهش نیز سعی بر آن بوده است تا نسبت به اثرسنجی قیمت­گذاری تراکم بر انتخاب وسیله افراد پرداخته شود. با توجه به عدم امکان مشاهده مستقیم اثرات قیمت­گذاری از روش رجحان بیان­شده برای ایجاد بانک اطلاعاتی استفاده شد. سناریوهای مختلف قیمت­گذاری مبتنی بر روشهای طراحی تجربی تهیه و در قالب پرسشنامه­هایی که حاوی سوالاتی در ارتباط با مشخصات اقتصادی – اجتماعی و ویژگیهای سفر  افراد بود، از کاربران مورد پرسش قرار گرفت. با توجه به سناریوهای قیمت­گذاری، 4 انتخاب شامل وسیله نقلیه شخصی، حمل و نقل همگانی همگانی،  تاکسی و عدم انجام سفر به کاربران ارائه شد. بیش از 3500 پرسشنامه جمع­آوری و پس از اعتبارسنجی اولیه وارد بانک اطلاعاتی شد. برای مدلسازی، با توجه به ماهیت گسسته داده­ها، از مدل لوجیت چندگانه استفاده شد و برای هر یک از انتخابها نسبت به پرداخت مدل اقدام شد. نتایج نشان داد قیمت­گذاری می­تواند به عنوان یک ابزار مناسب برای مدیریت تقاضای وسایل نقلیه شخصی بکار رود. به طوری که با تعیین عوارضی معادل 3000 تومان برای ورود به محدوده تنها 35 درصد از وسایل نقلیه شخصی استفاده می­نمایند و مابقی نسبت به تغییر وسیله یا برنامه سفر خود اقدام می­نمایند. نتایج نشان داد که 30 درصد از افراد نسبت به انتخاب گزینه حمل و نقل همگانی و 24 درصد نسبت به انتخاب گزینه تاکسی مبادرت می­ورزند. در نهایت وضعیت انتخاب وسیله افراد در قیمتهای مختلف بررسی و مورد بحث قرار گرفت.}, keywords_fa = {مدل انتخاب وسیله,قیمت‌گذاری تراکم,روش رجحان بیان شده}, url = {http://mcej.modares.ac.ir/article-16-7376-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7376-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {pam, maryam}, title = {Numerical analysis of electrokinetic soil remediation for Mercury removal}, abstract ={Electrokinetic soil remediation is a promising technology that can be used for insitu treatment of fine-grained soils. In this study the numerical analyses of electro kinetic process in soil is considered. Numerical model is formulated for simulating mercury transport under an electric field using one-dimensional convection-diffusion equation that describes contaminant transport. The presented model is used for demonstrating the pH changes and mercury removal from kaolinite clay at last day. The finite difference method is used for solving the model. Computational programs were written in two ways of FTCS and Crank-Nicolson using MATLAB software. The Crank-Nicolson scheme has been more consistent with experimental results. Experimental results are used for the calibration of the model. The proposed numerical model shows good agreement with experimental results.}, Keywords = {soil treatment - electrokinetic - heavy metal - mercury - numerical analysis}, volume = {14}, Number = {4}, pages = {149-158}, publisher = {Tarbiat Modares University}, title_fa = {حل عددی فرآیند اصلاح الکتروکینتیک برای خاک های آلوده به جیوه}, abstract_fa ={چکیده- اصلاح الکتروکینتیک یک تکنولوژی نوید بخش است که می­توان از آن برای پاکسازی خاک‌های ریزدانه در محل استفاده کرد. در این مطالعه حل عددی فرآیند الکتروکینتیک در خاک آلوده به جیوه مورد توجه قرار گرفته است. مدل عددی برای شبیه سازی انتقال جیوه تحت یک میدان الکتریکی با استفاده از معادله یک بعدی انتقال- انتشار توصیف کننده انتقال آلاینده فرمول‌بندی شده است. مدل ارائه شده برای نشان دادن تغییر pH و حذف جیوه از خاک رس کائولینیت استفاده می­شود. برای حل مدل از روش­های تفاضل محدود استفاده شده است. برنامه کامپیوتری در نرم افزار متلب به دو روش FTCS و Crank-Nicolson نوشته شده که طرح Crank-Nicolson به دلیل دقت بیشتر با نتایج بیشتر منطبق است. برای کالیبراسیون مدل از نتایج آزمایشگاهی استفاده شده است. مدل عددی پیشنهاد شده با نتایج آزمایشگاهی مطابقت خوبی نشان می­دهد}, keywords_fa = {تصفیه خاک,الکتروکینتیک,فلز سنگین,جیوه,حل عددی}, url = {http://mcej.modares.ac.ir/article-16-4-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-4-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Farshchi, Hamid Rez}, title = {APPLICATION OF SHEAR-FRICTION HINGE CONNECTION IN MID-STORY STAIR SLABS TO COLUMN JOINT}, abstract ={Reinforced concrete buildings are considered as one of the most important types of structures. According to the implementation nature of these buildings, mainly as in place construction, usually their connections are performed as fixed connections. Because of restraint form of girder-column connection in the reinforced concrete buildings, their participation in the lateral load bearing will be in the form of moment frame system. Nowadays stair -column connection in the middle of story is considered as one of the design and implementation problems. Since using of multiple arm stairs is the best method in terms of performance, cost and safety to make an appropriate connection between stories, different methods will be used to transfer landing plate (stations) load to structural members in order to increase stability and safety of the stairs. Two general methods of landing plate load transfer include: A) transfer of stations load to lower or upper balanced beam of the floor B) transfer of stations load to columns around the stair. In our country more attention is paid to the second method (B) due to the ease of implementation and financial and time savings. Fixed and unchangeable behavior of landing plate- column connections in the middle of story is one of the most important properties of a good connection. This target can be achieved largely through designing and implementing of joint connections of landing plates to columns. It is a long time that this connection is designed in our country as joint connection but there are no appropriate details of implementation for the given assumptions. Always in the typical methods there is a considerable moment imposed on the column because of restraint nature of in place reinforced concrete practice. It is clear that this unusual beam – column connection in the middle of story is considered practically an obvious weakness for these columns and the whole structure in terms of loading and final variable behaviors of several columns connected to half-height slab of the stairs.  Purpose of the present study is to introduce a new joint connection that is consistent with national building regulations, part 9 and also can be easily performed and designed. Suggested connection with a shear – friction function can be applied in the connection of slab stairs in the middle of the story to columns. It can also be considered as a suitable method for consistent relationship of design and implementation. Force transmission in this connection is just in a shear form (because moment arm is not formed) and mainly takes place by reinforcement bars. Although concrete connection friction can transmit substantial shear force; it is recommended to ignore this capacity. However, friction connection capacity is predictable and applicable in the theoretical relationships. Implementation of this connection is very simple and can be created just by preparation of several bars as antennae (dowel) with appropriate and minimum aanchorage length. Implementation of suggested connection leads to removal of the beam in the middle of the story staircase. Finally, it causes high amount of savings in the use of concrete, bars and shuttering and increases the accuracy and speed of implementation. According to loading of each staircase, amount of required reinforcement will be calculated based on shear force as well as tensile force.       }, Keywords = {--}, volume = {14}, Number = {4}, pages = {159-169}, publisher = {Tarbiat Modares University}, title_fa = {کاربرد اتصال برشی – اصطکاکی در اتصال مفصلی تیر میان طبقه راه پله بتنی به ستون}, abstract_fa ={ امروزه در ساختمان­های قاب خمشی بتنی اتصال پله در میان طبقه به ستون­ها یکی از مشکلات طراحی و اجرایی محسوب می­شود. این مشکل از آنجا ناشی می­شود که اتصال تیرمیان طبقه به ستون، در نرم‌افزار به صورت مفصل مدل‌سازی می­شود این در حالی است که اجرای این اتصال مفصلی به‌علت عدم جزییات اجرایی مناسب با فرض اولیه (اتصال مفصلی) تطابق ندارد. آشکار است این اتصال غیراصولی تیرمیان طبقه به ستون از نظر تغییر بارگذاری و در آخر تغییر رفتار چند ستون متصل به دال نیم طبقه پله، ضعفی آشکار برای این ستون­ها و کل سازه محسوب می‌شود. هدف از این پژوهش ارایه جزییات اتصالی ساده و اجرایی است که با عملکردی برشی – اصطکاکی برای اتصال دال پله در میان طبقه به ستون­ها قابل استفاده است. این اتصال براساس ظرفیت‌های موجود در ضوابط و مقررات ملی ساختمان، مبحث 9 تعریف شده و می‌تواند راهکاری مناسب برای تطبیق طراحی با اجرا باشد.}, keywords_fa = {تیرمیان طبقه,اتصال بتنی,راه‌پله,مفصل,ستون}, url = {http://mcej.modares.ac.ir/article-16-8965-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-8965-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {mohammadi, elahe}, title = {Elastoplastic analysis of the tunnel considering the nonlinear variations of the strength parameters from peak to residual in the strain softening stage}, abstract ={The ground response curve, (GRC), is one of the three important components of convergence- confinement method. In fact, this curve is obtained from elastic-plastic analysis of circular tunnel, which is various depending on the type of rock around an excavation, mechanical, geometrical features of it. Tunnel geometry, in situ stress, support pressure, intact rock features and fractured rock mass features, are among the effective factors on the ground response curve. Elastic-plastic analysis of a circular opening subjected to hydrostatic far-field stress has been one of the most fundamental problems related behavior of tunnels. The results of such analysis can be shown in the ground response curve. In this curve, the ratio of radial convergence of tunnel to inner pressure of tunnel is presented by with distance from tunnel face scale. This analysis can be expressed in this way relation between the convergence of the tunnel wall and radius of plastic zone around the tunnel. In this paper is presented a relatively simple procedure for the ground response curve of the circular tunnels excavated in strain softening behaviors, compatible with a nonlinear Hook-Brown yield criterion. In order to construct true GRC, it is necessary to think about the selection of the behavior parameters of rock mass and its yield criterion and analyses different states. Material with elastic-plastic behavior according to behavior after fracture are divisible to three groups including perfect plastic, perfect brittle and strain-softening. Based on the reviewed the present studies, strain-softening model is closer to behavior reality of rock masses, but the convincing methods for recognition of rocks with strain-softening behavior, has not been presented up to now. The main reason of this deficiency is the complexity of analysis of rock mass with strain-softening behavior. Lack of closed form solution for determining the relation between convergence of tunnel and inner pressure, add sth. to this problem. Most researchers, for investigation of strain-softening behavior of materials, have considered the change of the strength parameters from peak to residual in the strain softening zone as a linear function. Therefore in this article, in order to more precisely investigate the strain softening behavior, these variations are nonlinearly modeled. Therefore, dilation and friction angle parameters and the constants of the yield criterion are variable from the peak to the residual. In order to show the applicability and accuracy of the proposed procedure and investigate the effect of it in plastic region, some illustrative examples are presented here. First, the effect of different definitions for the softening parameter η is discussed by means of elasto-plastic analysis of a circular tunnel using Park, 2007 data . Second, the effect of variation of critical softening parameters on the displacement of a circular tunnel is examined by the proposed method using Carranza-Torres, 2004 data. Then the effect of different definitions for strength parameters from peak to residual, in the softening zone is evaluated by constructing the ground response curves for Park, 2007 data.}, Keywords = {Ground response curve,Strain softening behavior,Hook-Brown yield criterion}, volume = {14}, Number = {4}, pages = {171-178}, publisher = {Tarbiat Modares University}, title_fa = {تحلیل الاستوپلاستیک تونل با در نظر گرفتن تغییر غیرخطی پارامترهای مقاومتی از پیک به ماندگار، در مرحله نرم کرنشی}, abstract_fa ={در این مقاله یک روش نسبتاً ساده برای منحنی پاسخ زمین در تونل¬های دایره¬ای حفاری شده در توده سنگهای با رفتار نرم کرنشی، با بکارگیری معیار خرابی غیرخطی هوک- براون ارائه شده است. اکثر محققین تغییر پارامترهای مقاومتی از پیک به ماندگار, در ناحیه نرم کرنشی را, به صورت یک تابع خطی درنظر گرفته¬اند. در این مقاله به منظور بررسی دقیق¬تر رفتار نرم کرنشی، این تغییرات به صورت غیرخطی مدل می¬شوند. به این ترتیب پارامتر¬های اتساع، زاویه¬ی اصطکاک و ثابت¬های معیار خرابی از نقطه¬ی پیک به ماندگار ثابت نیستند. جهت بررسی دقت و کاربرد عملی روش پیشنهادی به مقایسه این روش با سایر روش¬های ساده سازی شده و دقیق از قبیل Park et al 2007 وet al 1983 Brown پرداخته شده است که نزدیکی بسیار زیاد نتایج حاصل از این روش, به نتایج روش Park حاکی از دقت بسیار زیاد روش تحلیلی پیشنهادی است. تأثیر مقدار پارامتر نرم¬کرنشی روی تغییر پارامترهای مقاومتی نیز با ترسیم منحنی پاسخ¬های مختلف بررسی شده است.}, keywords_fa = {منحنی پاسخ زمین,رفتار نرم کرنشی,معیار خرابی هوک- براون}, url = {http://mcej.modares.ac.ir/article-16-2030-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2030-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {manafi, ehs}, title = {Static analysis of urban single tunnels in alluvial using discrete element method (DEM)}, abstract ={Construction of urban tunnels (metro and transportation) is an integral part of the infrastructure of modern urban. Most of urban tunnels are located in alluvium. Major problem in construction of urban tunnels is settlement at the ground surface and its influence on buildings together the control of deformations around excavation area. Therefore, the accurate prediction of deformations is an important factor in tunnels projects. Because of the discontinuum nature of soils, its modeling using conventional FEM based on continuum mechanics is not completely real. Hence, in this research, considering alluvium as discrete particles, the effects of tunnel parameters such as diameter, depth and shape (construction method) on the ground deformations is examined using DEM (Discrete Element Method). For this concern, using software PFC2D based on DEM, the static analysis of circular tunnels is done. The results of DEM are compared with respect to the FEM, field data and analytical results. The comparison shows the results of DEM are more accurate than FEM especially in shallow depths and it can model the surcharge effect of tunnel smoothly.}, Keywords = {PFC2D,Tunnel,DEM,PFC2D,Static Analysis,Alluvial soil}, volume = {14}, Number = {4}, pages = {179-188}, publisher = {Tarbiat Modares University}, title_fa = {تحلیل استاتیکی تونل های منفرد شهری در آبرفت درشت دانه با استفاده از روش اجزاء مجزا}, abstract_fa ={ از نیازهای شهرنشینی مدرن امروزی ساخت تونل‌های شهری (مترو و راه) است. بسیاری از این سازه‌ها در محیط‌های آبرفتی و سست شهری قرار دارند. در ساخت تونل‌های شهری مهم‌ترین معضلی که با آن برخورد می شود نشست‌های به وجود آمده در سطح زمین و تأثیر آن بر سازه‌های سطحی است. علاوه بر این کنترل جابه‌جایی‌های اطراف ناحیه حفاری به منظور تأمین ایمنی سازه تونل از اهمیت زیادی برخوردار است. بنابراین تعیین دقیق جابه‌جایی‌های زمین هنگام ساخت تونل از ضروری‌ترین نیازهای پروژه است. با توجه به اینکه خاک، یک محیط ناپیوسته متشکل از ذرات با اندازه‌های مختلف است، پس در این پژوهش سعی شده است تا با استفاده از روش اجزاء مجزا که خاک را به صورت ذرات مجزا در نظر می‌گیرد، آثار پارامترهای هندسی مختلف تونل از قبیل قطر و عمق بر جابه‌جایی‌های زمین بررسی شود. بنابراین تحلیل دوبعدی استاتیکی تونل با فرض کرنش صفحه‌ای و با استفاده از نرم افزارPFC2D  که بر پایه روش اجزاء مجزا است، انجام شده، که نتایج به دست آمده با نتایج حاصل از نرم افزار PLAXIS2D که بر اساس روش اجزاء محدود است و همچنین داده‌های صحرایی و حل تحلیلی مقایسه شده است. نتایج بیانگر دقت بیشتر روش اجزاء مجزا نسبت به روش اجزاء محدود به خصوص در اعماق سطحی و همچنین مدل سازی بهتر تغییرات سربار است.}, keywords_fa = {تونل,روش اجزاء مجزا,تحلیل استاتیکی,آبرفت درشت دانه}, url = {http://mcej.modares.ac.ir/article-16-6426-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6426-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} }