@article{ author = {Aghakouchak, Ali Akbar and Ahmadi, Mohammadhas}, title = {Development of design method for structures equipped with yielding metallic dampers based on performance objectives}, abstract ={One of the effective ways to mitigate earthquake damage in structures is passive control of structures. Yielding metallic dampers economic passive control devices. Not only yielding metallic dampers are easy to erect, but they can also be used as a passive control systems easily. In this paper, the aim is to develop a design procedure for steel structures equipped with a combination of yielding metallic dampers so that, dampers will experience specific nonlinear behavior when subjected to various seismic hazard levels. For this purpose, the first step is providing seismic hazard spectra with different return periods for the intended site of construction. In this research, this step has been taken by using the Tehran probabilistic analysis hazard project data and then plotting uniform hazard spectra with 75-year, 475-year, 975-year and 2475-year return periods. After determination of uniform hazard spectra with mentioned return periods, behaviors of structures equipped with yielding metallic dampers have been investigated in the form of one-storey one-span, one-storey two-span and multi storey multi span frames. Required equations for behavior of these structures under monotonic loading is developed. In the beginning of design process, the performance criteria for the structure and the damper is set and by using the derived equations, design of single degree of freedom frames based on performance criteria has been carried out. These single degree of freedom structures have different periods and strength reduction factors. After designing the single degree freedom structures, nonlinear static analysis results have been compared with result of nonlinear time history analysis. For this purpose, 7 earthquake records have been chosen and scaled based on Iranian code of practice for seismic resistant design of buildings and used for dynamic analysis. Results showed that all performance criteria of 75-year and 475-year hazard levels have been satisfied but for 975-year and 2475-year hazard levels, six cases have not satisfied the desired critera with 6 percent error. In order to verify the presented numerical analysis of multi degree of freedom structures, an experimental study has been chosen and the results of these two works have been compared. This verification showed that the presented analysis can model the structures and dampers with acceptable accuracy. Performance criteria of multi degree freedom structures have also been proposed. Three, 3-storey, 6-storey and 9-storey buildings equipped with dampers have been designed and based on proposed method and the desired performance of dampers have been achieved. Time history analysis have been carried out for each return period. For these analyises, 7 earthquake records were chosen and scaled based on Iranian code of practice for seismic resistant design of buildings. Comparison of performance point displacement levels and the displacements obtained from 28 nonlinear analyses, showed up to 13 percent error. Meanwhile, the displacement levels of each set of dampers for 75-year, 475-year, 975-year and 2475-year return periods, confirmed efficiency of proposed design method and all dampers met the mentioned performance criteria. The results also showed that when hazard level increased, the difference between the results of nonlinear time history analyses and static nanlinear analyses have also increased.}, Keywords = {Performance Based Design,Uniform Hazard Spectrum,Yielding Metallic Damper,Nonlinear Static Analysis,Nonlinear Time-history Analysis,}, volume = {18}, Number = {5}, pages = {1-17}, publisher = {Tarbiat Modares University}, title_fa = {توسعه روش طراحی برای سازه‌های مجهز به ترکیبی از میراگرهای فلزی جاری شونده بر اساس اهداف عملکردی}, abstract_fa ={هدف از این مقاله، توسعه‌ی روش طرّاحی در سازه‌های فولادی مجهّز به ترکیبی از میراگرهای فلزی جاری شونده است، به‌نحوی‌که بتوان میراگرها را چنان طرّاحی کرد که در سطوح مختلف خطر لرزه‌ای، میزان معیّنی از رفتار غیر ارتجاعی را تجربه کنند. برای این منظور در ابتدا، رفتار سازه‌های مجهّز به میراگرهای فلزی جاری شونده در قالب قاب های یک طبقه‌ی یک دهانه، یک طبقه‌ی دو دهانه و چندطبقه‌ی چنددهانه بررسی شده و روابط مربوط به جابجایی این سازه‌ها تحت بار جانبی یکنوا به دست می آید. سپس برای طرّاحی سازه های یک درجه آزادی معیارهای عملکردی پیشنهاد شده و طرّاحی سازه های یک درجه ی آزادی انجام می شود. سازه‌های یک درجه‌ی آزادی دارای دوره‌های تناوب گوناگون و ضرایب کاهش مقاومت مختلفی می‌باشند. پس از طرّاحی سازه‌های مذکور، جهت اطمینان از ارضای معیارهای عملکردی پیشنهادی، جواب‌های حاصل از تحلیل استاتیکی غیر خطّی با جواب‌های تحلیل تاریخچه‌ی زمانی مقایسه می شوند. در آخر، قاب های خمشی سه ساختمان نمونه‌ی 3، 6 و 9 طبقه مجهز به میراگر فلزی جاری شونده با توجّه به معیارهای پیشنهادی طرّاحی و با استفاده از نتایج تحلیل‌های تاریخچه‌ی زمانی کارآمد بودن روش پیشنهادی بررسی می شود. نتایج تحلیل های تاریخچه ی زمانی غیر خطّی نشان می دهد که روش طرّاحی پیشنهادی می تواند معیارهای مورد نظر برای عملکرد میراگرها را برای سازه های یک و چند درجه ی آزادی اقناع نماید.}, keywords_fa = {طرّاحی بر اساس عملکرد,طیف خطر یکنواخت,میراگر فلزی جاری شونده,تحلیل استاتیکی غیر خطّی,تحلیل دینامیکی غیر خطّی,}, url = {http://mcej.modares.ac.ir/article-16-13254-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-13254-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Bijari, Mehran and Younesi, Habibollah and bahramifar, nader}, title = {Mesoporous activated carbon production from lignocellulose waste for removing reactive dyes Blue 19 and Blue 21 from aqueous solution}, abstract ={Mesoporous activated carbon production from lignocellulose waste for removing reactive dyes Blue 19 and Blue 21 from aqueous solution Introduction. Reactive dyes have been increasing in textile industries for dyeing natural and synthetic fibers. Discharge of dye- bearing waste-water makes an adverse effect on aquatic environment because the dyes give water undesirable color. The major environmental and health problems associated with water pollution caused by the discharge of untreated textile effluent are due to disorders in the aquatic environment because of use of toxic chemicals. The aim of this study was to investigate the adsorption potential of as-produced activated carbon from grape wood residue (Vitis Vinifera) in order to remove Reactive Blue 19 (RB19) and Reactive Blue 21 (RB21) dyes from aqueous solution. Activated carbon is the most common adsorbent for the removal of many dyes.Activated carbons are made from various agricultural wastes by physical and chemical activation. The preparation of activated carbon from agricultural waste could increase economic return and also provides an excellent method for the solid waste disposal thereby reduce pollution. Method: The adsorbates in this study included three reactive dyes, Reactive Red 23 (RR23), Reactive Blue 19 and Reactive Blue 21. All dyes were commercial grade and employed without further purification. The activated carbon was synthesized from grape wood biomass by activation of phosphoric acid (H3PO4) with impragnation ratios of 1:1 1:2,1:3, 1:4. The FTIR, BET, and SEM techniques were used to characterize the as-prepared carbon materials. In addition, dye adsorption experiments were carried out, which measurements are taken for all of the samples under in the same condition, at pH of 2, adsorbent dose of 0.01 g/l, initial dye concentration of 250 mg/l, sworking volume of 100 ml, and contact time of 120 min. Results and discussion: The results showed that the carbon sample activated under imprenation ratio of 1:4 and temperature of 600oC, that obtained a special surface area of 1850 m2/g, and total pore volume of 2.40 cm3/g, and pore size distribution of mesoporous at 86%, had maximum adsorption capacity of 1932 and 908 mg/g for RB19 and RB21 dyes, respectively. The adsorption behaviors of three reactive dyes (Reactive Blue 19 23, Reactive Blue 21) onto this biomass activated carbon were investigated in batch systems. The experimental data were analysed by the Langmuir, Freundlich and Sips models of adsorption. Equilibrium data of dyse fitted well with the Sips model. The rates of adsorption were found to conform to the pseudo-second-order kinetics with good correlation. The equilibrium adsorption capacity of the Activated carbon was determined with the Langmuir equation found to be 1914 mg/g for Reactive Blue 19 and 1195 mg/g for Reactive Blue 21. Conclusion: This study showed that activated carbon produced from annual pruning vineyards waste has a high potential in the treatment of textile wastewater. Also results indicate that Activated carbon from grape wood could be employed as low-cost alternative to commercial activated carbon in wastewater treatment for the removal of acid dyes. Keywords: Activated carbon, lignocellulose waste, Grape wood, Blue 19, Blue 21}, Keywords = {Activated carbon,lignocellulose waste,Grape wood,Blue 19,Blue 21,}, volume = {18}, Number = {5}, pages = {18-30}, publisher = {Tarbiat Modares University}, title_fa = {تولید کربن فعال مزوحفره از پسماند لیگنوسلولزی برای حذف رنگ‌های راکتیو بلو 19 و بلو 21 از محلول آبی}, abstract_fa ={تخلیه پساب تصفیه نشده صنایع نساجی به دلیل استفاده از ترکیبات سمی در آن‌ها‌ باعث آلودگی در محیط‌های آبی و مشکلات بزرگ زیست‌ محیطی و بهداشتی می‌شود. هدف از این مطالعه بررسی پتانسیل جذب کربن فعال تولید شده از پسماند چوب انگور (Vitis Vinifera) به منظور حذف رنگ‌های راکتیو بلو 19 (RB19) و بلو 21 (RB21) از محلول آبی است. کربن فعال از چوب انگور و با استفاده از فعال‌ساز اسید فسفریک (H3PO4) با نسبت‌های اشباع 1:1، 1:2، 1:3 و 1:4 سنتز شد. آنالیزهای BET،FTIR و SEM برای تعیین مشخصات کربن فعال انجام شد. همچنین آزمایش جذب رنگ برای همه نمونه‌ها در شرایط یکسان: pH برابر 2، دوز جاذب g/l 01/0، غلظت اولیه رنگ mg/l 250، دما C° 20، حجم محلول ml100 و زمان تماس 120 دقیقه انجام شد. نتایج نشان داد نمونه کربن فعال‌سازی شده در نسبت اشباع 1:4 در دمای C° 600 با سطح ویژه g/2m 1850 و حجم کلی حفرات g/3 cm40/2 و توزیع حفرات 86 درصد در محدوده مزوحفره با mg/g 1932 برای رنگ بلو 19 و mg/g 908 برای رنگ بلو 21 دارای حداکثر مقدار ظرفیت جذب است. این مطالعه نشان داد کربن فعال تهیه‌شده از پسماند حاصل از هرس سالیانه سرشاخه‌های درختچه مو از پتانسیل بالایی در تصفیه پساب صنایع نساجی برخوردار است.}, keywords_fa = {کربن فعال,ساختار مزوحفره,چوب انگور,بلو 19,بلو 21,}, url = {http://mcej.modares.ac.ir/article-16-14929-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-14929-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {HasanpouriNotash, Navid and Dabiri, Rouzbeh}, title = {Effects of Geofoam Panels on Static Behavior of Gravity Retaining Wall}, abstract ={Studies have shown that compressible materials between a rigid retaining wall and backfill reduced static and dynamic forces on the wall. Nowadays, panels with low density are used. Expanded polystyrene, which is one of the geo-synthetic products known as geofoam, is a compressible material. Geofoam is one of the geo-synthetic materials that are made of foam. Geofoam is very practical in geotechnical engineering due to its low bulk weight versus soil bulk weight and high compressibility, rapid and simple implementation, thermal insulation, and resistance against water absorption. It can be used in retaining walls, road construction projects as light fillers, and to reduce stress due to vertical loads in the base and sub base layers. Geofoam is one of the geosynthetic product which is made of lightweight expanded polystyrene (EPS) or extruded polystyrene (XPS). EPS geofoam is a block or planar rigid cellular foamed polymeric material that can be used in geotechnical applications. Studies have been shown that geofoam placed directly against a rigid retaining wall can reduce static loads on the wall. This study employed a finite difference method program, FLAC (Itasca, 2007), with considering yielding and non-yielding states for retaining walls to evaluate the effectiveness of geofoam panels in improving the statically behavior of retaining walls. To determine the effects of geofoam in soil displacement and earth force acting on the rigid wall, parameters such as the height of retaining wall, density and thickness of geofoam, cross-sectional shape of geofoam panel behind the wall, and also using of two geofoam panels with four panel spacing (50, 100, 150, 200 cm) have been studied via static analysis. In this numerical study three gravity –type retaining walls at heights of 3, 6 and 9 meters and geofoam panels with densities of 15, 20 and 25 (kg/m3) at three relative thicknesses of t/H=0.05, 0.2 and 0.4, were modeled. According to the results using of EPS15 with density equal to 15(kg/m3) which has the lowest density among other geofoam panels has a significant role in reducing of lateral stresses. Although the performance of geofoam in non-yielding retaining walls is better than yielding retaining walls. The results of the present research are as follows: 1- According to results, increasing the geofoam thickness increases soil lateral displacement and reduces forces on gravity retaining walls. The same effect can be achieved by reduction of geofoam density with equal thickness. In other words, Forces on gravity retaining walls are reduced and soil lateral displacement is increased by a reduction of geofoam density with equal thickness. 2- Using two geofoam panels with distance of 50 cm, unlike 3-meter high wall, is proper in the 6 and 9 meters yielding retaining walls. 3- Trapezoidal geofoam increases soil lateral displacement and reduces forces on retaining walls compared to a rectangular geofoam panel with the same cross-sectional area. 4- Effect of geofoam on the reduction of forces on non-yielding gravity retaining walls is more than that on yielding walls. 5- According to results, stiffness of geofoam panel (K=E/t) has significant role in reducing of lateral forces acting on retaining walls. In this study, it was observed that K≤5 MN/m3 provide the most effective range for the design of these system to reduce static forces acting on yielding retaining walls.}, Keywords = {Geofoam,Gravity retaining wall,Yielding and non-yielding wall,Numerical modeling,FLAC Software.,}, volume = {18}, Number = {5}, pages = {31-44}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی اثر ژئوفوم در رفتار استاتیکی دیوارهای حائل وزنی}, abstract_fa ={در تحقیق عددی حاضر با استفاده از نرم‌افزار تفاضل محدود FLAC در حالت تحلیل دوبعدی، به بررسی میزان تاثیر ژئوفوم در بهبود رفتار دیوارهای حائل وزنی در شرایط استاتیکی پرداخته شده‌است. از این‌رو به منظور تعیین میزان کارایی ژئوفوم در جابه‌جایی‌ها و همچنین نیروهای وارد بر دیوارهای حائل، پارامترهایی از قبیل ارتفاع دیوارهای حائل وزنی، چگالی و ضخامت ژئوفوم، تاثیر شکل قرارگیری ژئوفوم در پشت دیوار حائل، تاثیر استفاده از سیستم دو پانل ژئوفوم در این عملکرد مورد بررسی قرار گرفته‌است. دیوارهای حائل در ارتفاع‌های 3، 6 و 9 متری و ژئوفوم‌ها در چگالی‌های 15، 20 و 25 کیلوگرم بر متر مکعب که به ترتیب مربوط به EPS15، EPS20 و EPS25 می‌باشند، در ضخامت‌های نسبی 05/0 ، 2/0 و 4/0 مورد بررسی قرار گرفته‌اند. مطابق با نتایج، استفاده از EPS15، که دارای کمترین چگالی نسبت به بقیه ژئوفوم‌ها می‌باشد، نقش قابل توجهی در کاهش نیروها خواهد داشت. بنابراین در این تحقیق در بررسی اثر دو پانل ژئوفوم‌، از EPS15 در چهار فاصله قرارگیری 50 ، 100، 150 و 200 سانتی‌متری استفاده شده‌است. بررسی‌ها نشان داده‌اند، عملکرد ژئوفوم در دیوارهای حائل تسلیم‌پذیر متفاوت با دیوارهای حائل تسلیم‌ناپذیر می‌باشد. مطالعه‌های انجام گرفته توسط پژوهشگران نشان داده‌اند، میزان تاثیر ژئوفوم در کاهش نیروهای وارد بر دیوارهای حائل تسلیم‌پذیر کمتر از دیوارهای حائل تسلیم‌ناپذیر می‌باشد. در این تحقیق اثر استفاده از ژئوفوم در هر دو نوع دیوار حائل تسلیم‌پذیر و تسلیم‌ناپذیر مورد بررسی قرار گرفته‌است.}, keywords_fa = {ژئوفوم,دیوار حائل وزنی,دیوار حائل تسلیم‌پذیر و تسلیم‌ناپذیر,مدل‌سازی عددی,نرم افزار FLAC,}, url = {http://mcej.modares.ac.ir/article-16-13928-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-13928-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Heidary, Ramin and Ataei, Sh. and Ferestade, I.}, title = {Suggestion of fracture toughness for controlling the ballast materials quality.}, abstract ={Suggestion of fracture toughness for controlling the ballast materials quality. Abstract . . . . . . . . Among the existing transportation systems, rail transport systems have special privileges including high capacity, safety, economy and etc. Structure of railways is composed of two main sections of substructure and Superstructure. Ballast is a layer between sleeper and sub-ballast that is composed of broken stones. These stones have uniform gradation. Since ballast bears heavy loads, its high quality is important. If the ballast is gradually crushed and fines are generated, stone permeability and drainage property will be damaged and finally, instability will be resulted. If the above problems occur at ballast, its substitution is necessary that has high costs. Ballast layer quality depends on materials and their density. Ballast must be resistant against applied load. For Ballast quality control several tests has been suggested in 301 railway magazine that after the test on Ballast, the results are compared with allowable values and Ballast quality was controlled. Ballast grains subjected to train loads, contain numerous cracks. From the fracture mechanic point of view, when stress intensity factor at the crack tip reaches the mixed-mode fracture toughness, crack growth begins and Ballast grains crush. Ballast crushing and abrasion are the main reasons for ballast contamination which is the main source of various defects, particularly geometric defects in the railway. Since disc-type specimens are among favorite test samples for determining mode I and mixed mode fracture toughness in brittle materials like rocks, Therefore it is suggested to add the determination of the mixed-mode fracture toughness I and II with the semi-circular bend specimens subjected to three-point-bend loading to the ballast quality control in 301 railway magazine. In this research, discussed the importance of fracture toughness in extraction, crushing and operation of Ballast, then the finite element method and experimental is used to analyze a semi- circular disc specimens under bending load and the fracture toughness of two Ballast mine, Anjilavand and Gaduk was determined. Anjilavand and Gaduk mine is two Ballast mines in Iran that using them for Ballast layers in railway substructure. The crack parameters KI, KII and T are calculated for different mixed-mode from pure mode I to pure mode II. YI, YII, and T* are the non-dimensional forms of KI, KII, and T, respectively. These parameters are functions of the crack length ratio, the crack angle and also the location of loading supports in the semi-circular bend specimen. The curves of YI, YII, and T* extracted for various combinations of modes I and II. Since the results for mixed mode fracture resistance of brittle materials are usually presented in a normalized form as KII/KIc versus KI/KIc, where KIc is a material constant called the pure mode I fracture toughness, using the mixed-mode fracture criteria, capped failure modes I and II for both ballast rocks were extracted and compared. Fracture toughness of Anjilacvand specimen is greater than Gaduk specimen that shows the Anjiavand Ballast for operation in railway is better than Gaduk Ballast.}, Keywords = {Fracture toughness,Ballast,Semi-circular bend specimen,}, volume = {18}, Number = {5}, pages = {47-58}, publisher = {Tarbiat Modares University}, title_fa = {پیشنهاد چقرمگی شکست مود ترکیبی سنگ بالاست جهت کنترل کیفیت مصالح بالاستی}, abstract_fa ={دانه های بالاست دارای ترک های متعددی می باشند که تحت بار ناوگان عبوری قرار دارند و از دیدگاه مکانیک شکست وقتی ضریب شدت تنش در نوک ترک به مقدار چقرمگی شکست مود ترکیبی برسد رشد ترک آغاز می گردد که باعث خرد شدن دانه های بالاست می شود. خرد شدن و سایش دانه های بالاست عمده ترین دلیل ایجاد آلودگی در بالاست است که مهمترین منشا ایجاد عیوب مختلف بویژه عیوب هندسی در خط ریلی می باشد. بنابراین پیشنهاد می شود که تعیین چقرمگی شکست مود ترکیبی I و II با نمونه نیم دیسک تحت خمش سه نقطه ای به مجموعه آزمایشات کنترل کیفیت بالاست در نشریه 301 راه آهن اضافه شود. در نهایت چقرمگی شکست دو نمونه سنگ بالاست معدن گدوک و انجیلاوند به کمک آزمایشگاهی و عددی محاسبه شده و با استفاده از معیارهای شکست مود ترکیبی، پوش گسیختگی مود I وII دو نمونه سنگ بالاست مقایسه شده است.}, keywords_fa = {چقرمگی شکست سنگ,بالاست,نمونه نیم دایره تحت بار خمشی,}, url = {http://mcej.modares.ac.ir/article-16-15848-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15848-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {khedrimirghaed, pooria and varshosaz, ami}, title = {Effect of Suspended Anchored Spherical Energy Dissipator Blocks on Hydraulic Jump Characteristics}, abstract ={In an open channel, A hydraulic jump is the rapid varied flow which results water surface level increment and energy suppression. In most cases, by this phenomenon energy dissipation process is accomplished in downstream of hydraulic structures such as weirs, sluice gates and so on. The hydraulic jump is controlled by utilizing a structure called stilling basin. Building such structure can be very costly. Several approaches, such as bed roughness, chute blocks, baffle blocks and end sill, have been proposed to reduce the construction cost. For the first time, it is recommended to use the suspended anchored spherical energy dissipator blocks. From a practical point of view, this structure is very similar to baffle blocks but due to having less drag coefficient compared to the baffle blocks, they will suffer less force. Therefore, the slab thickness of basin decreases to a certain extent. Furthermore, due to fluctuations, using such dissipators leads to an increase in energy dissipation. These blocks have a relative density lower than water and are anchored by a thin resistant plastic to the floor of stilling basin. To the best of our knowledge, there are no studies on using these structures in the basin and analysis of their influences on the hydraulic jump characteristics. There are several interesting questions about the effect of such structures on the conjugate depth, jump length, and optimization of the design of the stilling basin as well. The main goal of our study is to answer these queries. In this work, 30 experiments were conducted in the range of froud numbers of 5-8 and in the form of four types of arrangement. It should be noted that, five experiments are concerned with testing the designed bed without any blocks. The Experiments were carried out in a flume with glass walls, 8 m length, 35 cm width and 40 cm heights. In order to form the hydraulic jump, the height of the walls were extended up to 80 cm in the beginning part of the flume and a chute with 30 degree angle and the height of 40 cm was set up. Next, in order to modeling such structures the obstacles diameter was set to 4 cm i.e. 1.2 times more than highest initial depth in classical hydraulic jump of present study. The size of the anchor length was chosen in such a way that the blocks do not enter into the roller environment and remain in front of impinging jet stream into the stilling basin, since no energy dissipation will occur if they enter into the roller ambient. The results showed that the arrangements decrease the jump length and conjugate depth respectively, in average to 31% and 21%. Additionally, the energy dissipation using the suspended blocks in average is around 68% that is approximately 11% greater than smooth bed. In all arrangements for experiments, conjugate depth reduction and energy dissipation increment is not impressive compared to each other, but even so the most and lowest effective arrangement respectively, was type 4 and type 3.}, Keywords = {Suspended Spherical Blocks,Energy Dissipation,Hydraulic Jump Length,Conjugate Depth,}, volume = {18}, Number = {5}, pages = {61-70}, publisher = {Tarbiat Modares University}, title_fa = {بررسی اثر بلوک‌های معلق کروی مهاری نوع جدید بر خصوصیات پرش هیدرولیکی}, abstract_fa ={زمانی که آب از روی سرریز یا مجراهای تحتانی مانند دریچه عبور می‌کند، جریان آن فوق بحرانی بوده و انرژی جنبشی زیاد و مخربی دارد. معمولا در این حالت برای اینکه انرژی جنبشی مخرب از آب گرفته شود، از پدیده‌ی پرش هیدرولیکی در سازه‌ای بنام حوضچه آرامش استفاده می‌شود. ابعاد حوضچه تابعی از مشخصات پرش می باشد. به منظور بهینه‌سازی این حوضچه‌ها اقداماتی از جمله قراردادن موانع در برابر جت جریان ورودی و یا ایجاد زبری در کف جهت افزایش تلاطم و استهلاک انرژی صورت گرفته است. بر اساس مطالعات صورت گرفته، برای اولین در تحقیق حاظر استفاده از بلوک‌های معلق کروی مهار شده به کف حوضچه آرامش پیشنهاد می‌شود. این نوع بلوک‌ها دارای چگالی نسبی کمتر از آب و بوسیله‌ی مهاری از جنس پلاستیک مقاوم به کف حوضچه متصل شده‌اند. ویژگی اصلی این موانع بر خلاف بلوک‌های صلب معمول، داشتن تحرک و نوسان متناسب با جریان عبوری از آن‌ها می‌باشد. به منظور بررسی اثر موانع آزمایشات در فلوم 35 سانتی‌متری آزمایشگاه مدل فیزیکی دانشگاه شهید چمران اهواز صورت گرفت. در پژوهش حاضر، چهار نوع آرایش به منظور مطالعه اثر آرایش این موانع در محدوده اعداد فرود 1/5-3/8 در نظر گرفته شد. نتایج نشان داد که عمق ثانویه، طول پرش هیدرولیکی و استهلاک انرژی در حضور این نوع بلوک‌ها نسبت به بستر صاف به ترتیب و بطور میانگین 21، 31 درصد کاهش و 11 درصد افزایش داشته است. همچنین مشخص شد که تغییر آرایش موانع تغییر چندانی در میزان استهلاک انرژی ایجاد نمی‌کند.}, keywords_fa = {بلوک‌های معلق کروی,استهلاک انرژی,طول پرش هیدرولیکی,عمق ثانویه,}, url = {http://mcej.modares.ac.ir/article-16-12907-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-12907-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {RezaeiFarei, Amirhas}, title = {Assessment of Optimized Face Pressure of Mechanized Tunneling in Granular Soils by Numerical Modelling}, abstract ={Estimating the pressure required to maintain the tunnel face is one of the most important factors regarding safe and optimal excavation using mechanized tunnel boring machines in urban areas. Applying a pressure more or less than the balance to the face would cause collapse and blow out in the tunnel face respectively. This pressure depends on several factors such as soil type and its engineering specifications, underground water conditions, excavation method, amount of surcharge and tunnel section area. In this paper, the influence of soil elasticity modulus, friction angle and underground water condition on the optimum amount of face pressure in granular soils were studied. For this purpose, a 3D finite element model was used employing the ABAQUS software (Ver. 6.14). The model takes into account relevant components of the construction process as separate components in the model (including: soil and ground water, tunnel lining and tail void grouting). Twenty-four steps have been performed according to the real construction sequences to achieve realistic model’s results. As regards, there are too many parameters involved in mechanized excavation, the geometry of tunnel, lining segments, injection grout and the surrounding soil properties are adapted from the under construction of Tabriz urban railway line 2 project. The tunnel surrounding soil above the ground water level were discretized by 8-node first order fully integrated continuum elements (C3D8). The tunnel lining and TBM shield were simulated by S8 shell elements. The soil under the ground water level and the grout material were modelled as saturated porous media using pore pressure elements (C3D8P). The soil behaviour was assumed to be governed by an elastic perfectly-plastic constitutive relation based on the Mohr–Coulomb criterion with a non-associative flow rule. Tunnel lining and TBM shield were simulated as an elastic behaviour. The ingress of ground water into the tunnel was not considered in this study. The paper gives a detailed description of the model components and the stepwise procedure to simulate the construction process. More than 70 3D models were analyzed and optimum pressure in the tunnel face was determined through measuring the amount of induced average displacement in the tunnel face. For various elasticity modulus, internal friction angle and underground water conditions different values of face pressure were applied in tunnel face and corresponding average tunnel face displacement were measured for each state. Results show that elasticity modulus of soil has a remarkable effect on the amount of the optimized face pressure and for minimize the tunnel face displacement, elasticity modulus should be considered in calculation of the applied face pressure. As the soil elasticity modulus increase the value of optimum face pressure decreases. Also the face pressure was calculated using analytical and experimental methods and the results were compared with the obtained optimum pressure. The results are in good agreement with those obtained from the COB method. In the cases with low elasticity modulus (less than 20 MPa in this study) the COB method obtained face pressures are less than optimal pressure resulted in this study. This difference increase with lowering of ground water level.}, Keywords = {Face Pressure,Mechanized Tunneling,Elasticity Modulus,Granular Soils,Abaqus.,}, volume = {18}, Number = {5}, pages = {71-78}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی فشار مناسب جبهه کار تونلهای مکانیزه حفاری شده در خاک های دانه‌ای با استفاده از مدلسازی عددی}, abstract_fa ={برآورد فشار لازم برای نگهداری جبهه کار تونل، یکی از مهمترین عوامل حفاری ایمن و مناسب با استفاده از ماشین‌های حفار مکانیزه در نواحی شهری است. در مقاله حاضر، با استفاده از نرم افزار المان محدود ABAQUS به بررسی تأثیر پارامترهای مدول الاستیسیته، زاویه اصطکاک داخلی و شرایط آب زیرزمینی بر روی میزان مناسب فشار جبهه کار در خاک‌های دانه‌ای پرداخته شده است. پس از صحت سنجی با نتایج ابزار بندی پروژه خط 2 قطار شهری تبریز، بیش از 70 مدل سه بعدی تحلیل و با اندازه‌گیری مقادیر جابجایی‌های جبهه کار تونل به ازای مقادیر متفاوت فشار جبهه کار و پارامترهای مختلف مورد بررسی، مقدار مناسب فشار جبهه کار تعیین شده است. بر اساس نتایج حاصل مدول الاستیسیته خاک تأثیر قابل توجهی در مقدار فشار مناسب جبهه کار دارد. همچنین، مقدار فشار جبهه کار حاصل از روش‌های تحلیلی و تجربی با مقدار مناسب بدست آمده مورد مقایسه قرار گرفته است که نتایج حاصل دارای بیشترین تطابق با روش COB می‌باشد.}, keywords_fa = {فشار جبهه کار,تونلسازی مکانیزه,مدول الاستیسیته,خاکهای دانه‌ای,مدلسازی عددی,}, url = {http://mcej.modares.ac.ir/article-16-20264-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-20264-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Zamani, Aylin and Mousavi, Seyed Roohollah and BeheshtiNezhad, Hossei}, title = {Influence of stirrups spacing on the flexural strength of lap spliced beams in corrosion condition}, abstract ={The lap-splice length of reinforcing bars is one of the practical aspects of the bond between concrete and reinforcing bars. Providing the adequate bond between the reinforcing steel and concrete in splice length is essential in structural concrete design. The bond strength of spliced bars in concrete depends on several factors such as surface deformation of reinforcing bars, embedment length, concrete cover, bar diameter, confinement, concrete strength and environment conditions. One of the major degradation processes of bond strength in reinforced concrete is the corrosion of reinforcement. In addition, to reducing the bond strength, corrosion of reinforcement leads to reduced flexural capacity and serviceability of reinforced concrete structures and ultimately affecting the structural safety. There has been little discussion about the simultaneous effect of stirrup spacing and corrosion of reinforcements on bond strength and flexural strength of lap-spliced reinforced concrete beams. Therefore, in this research, the simultaneous effect of stirrups distance and corrosion level on the flexural strength and behavior of lap-spliced reinforced concrete beams with different stirrups spacing was experimentally investigated. A total of 12 reinforced concrete beams were constructed and tested. The test beams were 150 mm deep, 100 mm wide, and 1500 mm long. The beams were divided into three main groups according to the type of reinforcement corrosion, S: stirrup corrosion, T: tensile rebar corrosion, and W: stirrup and tensile rebar corrosion. Three different stirrup spacing (53mm, 80mm, and 160mm in splice length) were considered in each group. After constructing and curing the specimens for 28 days, we fully immersed them in ponds containing chloride sodium 5%, and accelerated corrosion procedure was simulated for them by applying an electrochemical method. The accelerated corrosion process was induced by impressing a constant direct current 150 µA/cm2, on average, on the tensile steel bars. The degree of corrosion in all of the beams was 10%. After the accelerated corrosion process was completed, the beams were subjected to four-point loading by a 100-ton universal testing machine with a speed of 2 mm/min. The results are discussed in terms of normalized bond strength and residual ultimate strength of corroded beams with different stirrups spacing in each group. The rust products of bar corrosion had greater volume than the steel which increases stress in the concrete and results in cracks in splice length in all beams. Due to these cracks, the bonding of bar and the concrete decreased. The use of stirrups with low spacing in splice length can increase the bond strength by controlling the crack widths and maintaining the bonding of concrete surrounding reinforcement. Of course it should be noted that in specimens in group S, the decrease of stirrup spacing led to decline the ultimate strength capacity. Corrosion cracks interaction was the cause of reducing the confinement of longitudinal reinforcements in Group S. At the same degree of corrosion, the average reduction of flexural strength in Groups S, T and W were 15.3%, 7.5% and 14.3%, respectively. The experimental results obtained in this study are close to the results of Esfahani and Orangan equations, and the amount of existing error can be corrected using the correction factor.}, Keywords = {Corrosion,Lap spliced,Bond strength,Stirrup,}, volume = {18}, Number = {5}, pages = {79-90}, publisher = {Tarbiat Modares University}, title_fa = {تاثیر فواصل خاموت بر مقاومت خمشی تیرهای وصله‌دار تحت شرایط خوردگی}, abstract_fa ={تأمین پیوستگی کافی بین بتن و میلگرد در طول وصله یک نیاز ضروری برای طراحی سازه‏های بتن مسلح بشمار می‏آید. یکی از عوامل کاهش مقاومت پیوستگی، خوردگی میلگردهای فولادی سازه‌های بتن مسلح است. در این تحقیق به منظور بررسی تاثیر همزمان فاصله خاموت و خوردگی بر مقاومت پیوستگی میلگرد و بتن در تیرهای بتن مسلح با میلگردهای وصله شده تعداد 12 عدد تیر به ابعاد 1500×150×100 میلی‌متر در سه گروه، S: خوردگی خاموت، T: خوردگی میلگرد کششی، W: خوردگی توأم خاموت و میلگردکششی ساخته و تحت آزمایش قرار گرفتند. فواصل خاموت در ناحیه وصله 160، 80 و 53 میلیمتر و درجه خوردگی در کلیه تیرها 10% بود. پس از اتمام زمان خوردگی و رسیدن به درجه خوردگی هدف، کلیه تیرها تحت آزمایش خمش چهار نقطه‏ای شکسته شدند. نتایج نشان داد بطور میانگین کاهش مقاومت تیرهای S، T و W پس از خوردگی به ترتیب 3/15، 5/7 و 3/14 درصد می‏باشد. افزایش تعداد خاموت در ناحیه وصله سبب افزایش مقاومت در تیرهای گروه T و W می‌باشد که این روند در تیرهای گروه S به‌صورت معکوس است.}, keywords_fa = {خوردگی,وصله,مقاومت پیوستگی,خاموت,}, url = {http://mcej.modares.ac.ir/article-16-12797-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-12797-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {}, title = {}, abstract ={}, Keywords = {}, volume = {18}, Number = {5}, pages = {91-103}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی میزان انحراف رفتار راننده پیرو نسبت به راننده ایده‌آل در آشفتگی جریان ترافیک با استفاده از تحلیل پوششی داده‌ها}, abstract_fa ={ترافیک حرکت–توقف در آزادراه‌ها، منجر به آشفتگی جریان ترافیک و افزایش تأخیر می‌شود. وسایل نقلیه پیرو در زنجیره داده‌های عبوری در زمان ورود و خروج از آشفتگی به سبب ذات غیرقابل‌پیش‌بینی رفتار رانندگی، الگوهای رفتاری متفاوتی نسبت به اثر موج حرکت–توقف نشان می‌دهند. الگوهای رفتاری راننده پیرو در زنجیره وسایل نقلیه با استفاده از تئوری نامتقارن رفتاری در فاز کاهش شتاب به دو الگوی رفتاری زیرواکنشی‌ روواکنشی منتهی می‌شود. راننده پیرو بر اساس الگوهای رفتاری در فاز کاهش شتاب، پاسخ‌های متفاوتی نسبت به موج کاهش شتاب دریافتی نشان می‌دهد که منجر به افت سرعت کم‌تر یا بیشتری نسبت به راننده ایده‌آل، و تأخیر بیشتر یا کم‌تر در زنجیره حرکت وسایل نقلیه می‌شود. در این مقاله، دو پارامتر انحراف رفتار و زمان تغییر رفتار راننده پیرو نسبت به راننده ایده‌آل، بر اساس مدل تعقیب خودرو نیویل، در فاز کاهش شتاب نسبت به موج کاهش شتاب انتشاریافته در زنجیره وسایل نقلیه شناسایی می‌شود. به منظور شناسایی کم‌ترین زمان تأخیر در زنجیره وسایل نقلیه در فاز کاهش شتاب، روش تحلیل پوششی داده‌ها به کار گرفته شد تا کارا‌ترین میزان انحراف رفتار و زمان تغییر رفتار راننده پیرو متناسب‌ ‌با ‌موج کاهش شتاب دریافتی و سر‌‌فا‌‌‌‌صله مکانی پیرو در زمان دریافت موج تعیین شود. نتایج نشان دادند که بر اساس الگوی رفتاری زیرواکنشی در سرعت‌ها و سرفاصله‌های مکانی مختلف، راننده پیرو به رانندگی با الگوی رفتاری خود تمایل دارد، درحالی‌که مقدار موج انتشاریافته از وسیله پیشرو تأثیری بر خروجی‌ها ندارد. نتایج ذکرشده منجر به تأخیر کم‌تر در زنجیره وسایل نقلیه می‌شود.}, keywords_fa = {ترافیک حرکت – توقف, انحراف رفتار, الگوهای رفتاری, تحلیل پوششی داده‌ها}, url = {http://mcej.modares.ac.ir/article-16-30222-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-30222-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {sahraeimoghadam, amirhosein and Omidinasab, Fereydoon and dalvand, ahm}, title = {Impact resistance of multi-layer slabs made with (HPSCC) reinforced by fiber under the projectile impact at high speed}, abstract ={In this study, the impact strength multi-layer slabs reinforced by steel and nylon fibers, as well as the combination of these two fibers under the influence high velocity projectile, was investigated. To achieve this goal, 30 slabs one layer and three layers with dimensions 40 *40 * 7.5 cm were reinforced by 1% of the fiber, 30 slabs made 10 different models , each with 3 models Sample was made. A non-fiber model, as a control sample, and other slabs all have a constant volume 1 percent fiber, the difference being in the type and composition the fibers in different layers the slabs. The slabs were made with Kalashnikov , PK Kalashnikov and Dragunov guns at a distance 50 meters tested. In the test the projectile's encounter, three parameters penetration depth, area the damaged front and rear area and the volume damaged area in the samples were calculated and compared. Based on the results obtained, steel fibers can increase the resistance concrete slabs against the impact the projectile and reduce the surface area and volume the damaged area and significantly reduce the penetration depth. Steel fibers at best reduced the penetration depth 64 % in the kalashinkov gun and reduced the area and volume the damaged area in the dragunov weapon by 88 % and 98 % respectively. Also, steel fibers can prevent crack expansion by increasing the bond strength, provided that the fibers the nylon have a much lower impact than steel fibers. the nylon fiber could reduce the penetration depth and demolition area the sample in kalashnikov weapon by 37 % and 59 %, respectively, and reduce the volume damaged area in the dragunov weapon by 84 %, respectively. In addition, in this research, 12 samples cubic pressure were placed on the side 10 cm, 12 cylindrical tensile samples 10 × 20 cm and 12 small flexion beams with dimensions 32 *8 *6 cm and tested. It was observed that steel and nylon fibers cannot have a significant effect on the compressive strength, As a result the addition one percent the steel fiber, nylon and a combination these, this increase is 7.7, 2.6 and 6.4 % , which can be neglected. but steel fibers can significantly increase the tensile and flexural strength the concrete. addition one percent the steel fiber could create a 2.5 – fold increase in tensile strengths and increase the resistance 2 - fold in bending specimens. This is the nylon fibers do not have a significant impact on the tensile and flexural strength. Adding one percent the nylon fibers in the tensile and flexural samples could increase the resistance these specimens by 16 % and 24 % respectively. It was observed in the bending test of beams that steel and nylon fibers can be bent by bending in the cracks to increase the shape the weld so that the change in the maximum area the beam with the addition one percent steel fiber from about 4 mm in the control sample increase to about 25 mm.}, Keywords = {impact resistance,multilayer slabs,steel fibers,nylon fibers,projectile impact,}, volume = {18}, Number = {5}, pages = {105-118}, publisher = {Tarbiat Modares University}, title_fa = {مقاومت ضربه ای دال های چند لایه ساخته شده با بتن توانمند خودمتراکم الیافی تحت اثر برخورد پرتابه با سرعت زیاد}, abstract_fa ={در این پژوهش مقاومت ضربه‌ای دال های چندلایه مسلح شده به الیاف فولادی، پلاستیکی و ترکیبی از این دو الیاف تحت اثر برخورد پرتابه با سرعت زیاد بررسی شد. برای تحقق این هدف، تعداد 30 عدد دال یک‌ لایه و سه لایه با ابعاد 7/5*40*40 سانتی‌متر مسلح شده به 1 درصد الیاف ساخته شد،30 عدد دال ساخته شده از 10 مدل متفاوت می‌باشند، از هرمدل، 3 نمونه ساخته شد. 1 مدل بدون الیاف بعنوان نمونه شاهد و دیگر دال‌ها دارای حجم ثابت 1 درصد الیاف می‌باشند که تفاوت آن‌ها در نوع و نحوه ترکیب الیاف ها در لایه‌های مختلف می‌باشد. دال‌های ساخته شده با سه اسلحه متفاوت در فاصله 50 متر آزمایش شدند. بر اساس نتایج،الیاف فولادی می‌تواند مقاومت دال‌های بتنی را در مقابل ضربه پرتابه افزایش و سطح و حجم ناحیه تخریب شده و عمق نفوذ را به میزان چشم‌گیری کاهش دهد. الیاف فولادی می‌تواند با افزایش انسجام دال از گسترش ترک‌ها جلوگیری نماید، در صورتی که الیاف‌های پلاستیکی تاثیر به مراتب کمتری نسبت به الیاف‌های فولادی دارند. در این تحقیق تعداد 12 عدد نمونه فشاری مکعبی، 12 عدد نمونه کششی استوانه‌ای و 12 عدد تیر خمشی کوچک نیز ساخته و آزمایش شد. و مشاهده شد که الیاف فولادی و پلاستیکی نمی‌توانند تاثیر محسوسی بر روی مقاومت فشاری داشته باشند، اما الیاف فولادی می‌تواند مقاومت کششی و خمشی بتن را بصورت قابل توجهی افزایش دهد. این در صورتی است که الیاف پلاستیکی تاثیر قابل توجهی بر روی مقاومت کششی و خمشی نخواهد داشت.}, keywords_fa = {مقاومت ضربه‌ای,دال‌های چند‌لایه,الیاف فولادی,الیاف پلاستیکی,ضربه پرتابه,}, url = {http://mcej.modares.ac.ir/article-16-16786-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-16786-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Eyvazi, Behzad and Jamshidi-Zanjani, Ahmad and khodadadi, Ahm}, title = {Removal of chromium (VI) by adsorption on Manganese ferrite Nanoparticles: kinetic and thermodynamic study}, abstract ={The present study aimed to remove hexavalent chromium from aqueous solution by manganese ferrite nanoparticle. In this study, MnFe2O4 was prepared based on co-precipitation method. The adsorbent properties were determined using scanning electron microscopy (SEM), X-ray diffraction (XRD). In this research, the effects of pH (2, 5, 7, 9 and 11), contact time of 2 to 360 minutes and concentrations of 1 to 200 mg/l and temperature (283 to 328 K) for the removal of hexavalent chromium were investigated. The agitation parameter was kept constant for all experiments at 170 rpm. The results of nanoparticle synthesis showed that the nanoscale dimensions were less than 200 nm, and the shape of the spherical particles followed the cubic spinel structure. Moreover, the pH of zero point of the nanoparticle was 6.8. Kinetic studies showed that the removal of chromium followed the second-order kinetic model. Intrinsic particle diffusion model showed that single-particle intrusiveness was not present and absorption consists of two steps: first, pushing the absorbent layer onto the adsorbent surface and then penetrating the molecule inside the pores. It was found that the removal of chromium is followed the Langmuir model, and the maximum absorption capacity of the hexavallent-chrome is 34.84 mg/g. The resulting value of n=2.92 (Freundlich isotherm) indicates the chemical absorption of chromium on the adsorbent of hexavalent chromium. The highest adsorption rate occurred at 328 ° K. The amount of ΔG was negative and ΔH reacted positively. This is because that chromium-reacted manganese ferrite is chemically thermostable and spontaneous.  }, Keywords = {Chromium, Nano-Manganese ferrite, Kinetics, Thermodynamics, Isotherm}, volume = {18}, Number = {5}, pages = {119-132}, publisher = {Tarbiat Modares University}, title_fa = {حذف یون کروم شش ظرفیتی با جذب بر روی نانو ذرات فریت منگنز: مطالعه سینتیک و ترمودینامیک}, abstract_fa ={نانو ذرات فریت منگنز MnFe2O4 جاذب مؤثری برای حذف مواد آلی و غیر آلی است. در این مطالعه MnFe2O4 با استفاده از روش همرسوبی تهیه شد. ویژگی­های جاذب تهیه­شده با استفاده از XRD و SEM تعیین شد. جاذب تهیه‌شده برای حذف کروم شش ظرفیتی از محلول آبی مورد سنجش قرار گرفت. نتایج حذف کروم از محلول آبی نشان داد که کروم شش ظرفیتی در pH معادل 2 به‌طور مؤثرتری حذف شده است. مطالعات سینتیکی نشان داد که حذف کروم از مدل سینتیکی مرتبه دوم تبعیت می­کند. مدل نفوذ درون ذره­ای نشان داد که نفوذ درون ذره‌ای تک مرحله‌ای نبوده است. مشاهدات ایزوترم نیز بیان­گر آن بود که حذف کروم شش ظرفیتی با مدل لانگمویر مطابقت دارد و ماکزیمم گنجایش جذب کروم شش ظرفیتی 84/34 میلی­گرم بر گرم است. اثر دما در حذف کروم نشان داد که مقدار G∆ واکنش منفی و مقدار H∆ واکنش مثبت است. از این رو واکنش کروم شش ظرفیتی با فریت منگنز به‌صورت شیمیایی گرماگیر و خودبه‌خودی است. نتایج بیان‌گر این موضوع است که نانو ذرات فریت منگنز به‌عنوان جاذب مؤثری برای حذف منابع آب آلوده شده به کروم شش ظرفیتی می‌تواند مورد استفاده قرار گیرد.  }, keywords_fa = {کروم شش ظرفیتی, نانو ذرات فریت منگنز, سینتیک, ترمودینامیک, ایزوترم}, url = {http://mcej.modares.ac.ir/article-16-18996-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-18996-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {fallahi, moein and Rajabi, Ahmad and Yaghobi, Behrooz}, title = {Prediction the Scour Depth At Downstream of Bucket Spillway Using the Extreme Learning Machine and K-Fold Cross Validation}, abstract ={The ogee spillways are constructed to regulate the flow in reservoir of dams. When the excess waters overflow the ogee spillway, the velocity at toe of spillway is pretty high and the flow has a huge amount of energy. The bucket spillway is used in order to reduce the amount of such energy. Next, the trajectory flow combines with air and the flow loses its energy significantly. If the materials at downstream of spillway are erodible, the probability of the scour exist; as a result, the stability of spillway endangers. Therefore, the prediction of scour hole depth in this area is quite significant. In this study, the depth of scour at downstream of the bucket spillway simulated using the Extreme Learning Machine (ELM) model. One of the most popular methods based on the artificial intelligence is the feed-forward neural network (FFNN). The training speed of this algorithm is very low. It's due to the use of the gradient based algorithms such as the back propagation (BP) which has low speed and the adjustment of the parameters related to the network is iterative. The extreme learning machine (ELM) is a Single Layer Feed-Forward Neural Network (SLFFNN) which selects the number of nodes randomly and determines the output weights analytically. This algorithm is much faster than conventional neural networks and has a good generalization performance. The use of this method has had a good performance in different fields and its comparison with FFNN-BP has showed that this method in addition to reduce high computational costs has a higher accuracy. In current study, to evaluate the performance of ELM models, the Monte Carlo simulation (MCs) is applied. Monte Carlo simulation is a broad class of computational algorithms that rely on repeated random sampling to obtain numerical results. Their essential idea is using randomness to solve problems that might be deterministic in principle. They are often used in physical and mathematical problems and are most useful when it is difficult or impossible to use other approaches. Monte Carlo simulation is mainly used in different problems such as optimization and numerical integration from a probability distribution. Also in this study, the k-fold Cross Validation (k-fold) is used for evaluating the models ability. In k-fold cross validation method, the original sample is randomly partitioned into k equal sized subsamples. In the k subsamples, a single subsample is retained as the validation data for testing the specific model, and the remaining k-1 subsamples are used as training data. The cross-validation process is then repeated k times (the folds), with each of the k subsamples used exactly once as the validation data. The k results from the folds can then be averaged to produce a single estimation. The advantage of this method over repeated random sub-sampling is that all observations are used for both training and validation, and each observation is used for validation exactly once. The k value was considered 5 in this study. In this study, to validate the results of numerical models, the Azmathullah et al. (2005) experimental measurements were used. They measured the scour depth at the downstream of bucket spillway. Next, the effective parameters on scour depth were identified and six ELM models defined. In other words, one model simulated the scour depth with combination of five input parameters including the discharge dimensionless parameter, the ratio of the total head to the tailwater depth(H/dw), the ratio of the bucket radius to the tailwater depth(R/dw), the ratio of the mean sediment size to the tailwater depth(d50/dw) and lip angle of bucket, and five models predicted the output variable using four input parameters. In addition, the sensitivity analysis was carried out in order to identify the effective factor. This sensitivity analysis showed that the discharge dimensionless parameter was the most effective factor. Also, the superior model was introduced by analyzing the results of all models. This model had reasonable accuracy and was the function of all input parameters. For example, the determination coefficient and scatter index were obtained 0.993 and 0.071, respectively. Also, The RMSE and MAPE for this model were obtained 0.240 and 8.891, respectively. Additionally, the maximum, minimum and average discrepancy ratios for the superior model were respectively calculated 1.567, 0.360 and 0.991.}, Keywords = {Scour depth,Bucket spillway,Modeling,Extreme Learning Machine,k-fold Cross Validation,}, volume = {18}, Number = {5}, pages = {133-142}, publisher = {Tarbiat Modares University}, title_fa = {پیش‌بینی عمق آبشستگی در پائین‌دست سرریز جامی شکل توسط مدل ماشین آموزش نیرومند و روش اعتبار سنجی چند لایه}, abstract_fa ={در این مطالعه، عمق آبشستگی در پائین‌دست سرریزهای جامی با استفاده از مدل ماشین آموزش نیرومند شبیه‌سازی گردید. ماشین آموزش نیرومند یک نوع شبکه عصبی تک لایه پیش‌خور است که گره‌های محاسباتی را به‌صورت تصافی انتخاب کرده و وزن‌های خروجی را نیز به‌شکل تحلیل تعیین می‌نماید. علاوه براین برای سنجش توانایی مدل‌های ماشین آموزش نیرومند از شبیه‌سازی‌های مونت کارلو استفاده می‌شود. شبیه‌سازی مونت کارلو یک طبقه‌بندی گسترده از الگوریتم‌های محاسباتی است که از نمونه‌گیری تصادفی برای محاسبه نتایج عددی استفاده می‌کند. همچنین از روش اعتبار سنجی چند لایه برای بررسی توانایی مدل‌های عددی بهره گرفته می‌شود. در روش اعتبار‌سنجی چند لایه ای، نمونه اصلی است به طور تصادفی به k نمونه های فرعی به اندازه مساوی تقسیم شود. مزیت این روش، تکرار تصادفی نمونه های فرعی در روند آزمون و آموزش برای کلیه مشاهدات است و هر مشاهده دقیقا یک‌بار برای اعتبار‌سنجی مورد استفاده قرار می‌گیرد. در این مطالعه مقدار k مساوی با 5 در نظر گرفته شد. سپس پارامترهای تاثیر گذار بر روی عمق آبشستگی شناسایی شد و شش مدل ماشین آموزش نیرومند تعریف گردید. با انجام آنالیز حساسیت موثرترین پارامتر که شامل پارامتر بدون بعد دبی معرفی شد. همچنین با تجزیه و تحلیل نتایج مدل‌های مختلف، مدل برتر معرفی گردید. این مدل مقادیر آبشستگی را با دقت قابل قبولی پیش‌بینی کرد و تابعی از کلیه پارامترهای ورودی بود. به‌عنوان مثال مقادیر ضریب تببین و شاخص پراکندگی به ترتیب مساوی 993/0 و 071/0 بدست آمد.}, keywords_fa = {عمق آبشستگی,سرریز جامی شکل,مدل‌سازی,ماشین آموزش نیرومند,اعتبار سنجی چند لایه,}, url = {http://mcej.modares.ac.ir/article-16-13346-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-13346-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Ghaseminejad, Vali and rowshanzamir, mohamm}, title = {Effect of aspect ratio on behavior of bucket foundations under combined loading in sand}, abstract ={Suction caissons have been extensively used in oil and gas industry. Recently bucket foundations are considered an innovative foundation solution to offshore wind turbines. Skirted foundations are increasingly used in the design of offshore wind turbine structures and facilities to withstand combined vertical, horizontal and moment loading conditions. In this study, three-dimensional finite element models of bucket foundations in medium dense sand were analyzed under combined loading. Numerical models were validated by comparing the results of finite element analysis. Sensitivity analyses were performed at different length-to-diameter aspect ratios under combined load with different load eccentricities. The responses of combined load, from pure horizontal load to overturning moments with varying tower heights, to pure moments were compared. Results showed how combined bearing capacity of foundations would depend on aspect ratio and loading conditions. Ultimate limit states were represented as normalized capacities, and the expressions were derived from the results of analysis. Offshore applications of shallow foundations are not limited to the oil and gas industry. In fact, they are recently being used as a new solution to wind turbines. Offshore wind turbines are relatively sensitive to deformations, particularly tilting. In order to withstand against tilting due to wind and wave loads and large lateral and overturning forces, the foundations of offshore wind turbines are setup with peripheral steel skirts which transmit the seabed, trapping a soil plug. Foundations of offshore structures require carrying a very small vertical load, but large horizontal loads and overturning moments. Suction buckets are circular shallow foundations with large diameter, closed at top and open at bottom. Bucket foundations penetrate into the seabed by its self-weight to provide a seal between the skirt tip and the soil and then penetrate by applying an under-pressure inside the skirt compartment until full contact with the soil is obtained. The bearing capacity of the bucket foundations under combined loads increases due to embedment by comparison with a surface foundation (L/D = 0). The bearing capacity behavior of the bucket foundations can be expressed through failure envelopes that expand with increasing aspect ratio. In the literature, it is not clearly and quantitatively clarified how the bearing capacity depends on bucket embedment length but can be stated with increasing aspect ratio, failure mechanisms are forced deeper within the soil mass. In November 2002 the first Suction bucket foundation for using of the wind energy converter was installed at the large scale test facility in Frederikshavn. The project was at the time being the largest wind turbine in Denmark. Its total height of turbine was equal 125 m with a bucket diameter of 12 m and skirt length of 6 m (i.e. L/D =0.5) In this report, the effect of aspect ratio on combined bearing capacity of bucket foundations installed in saturated medium dense sand was evaluated. Load-deformation behavior of suction buckets under loads was investigated and compared. The analysis was carried out by loading bucket foundations with a load that allowed the bucket to move freely. When considering the design of the foundations of offshore wind turbines, it is important to understand their elastoplastic deformation behavior as well as ultimate capacities.}, Keywords = {Bucket foundation,aspect ratio,finite element analysis,bearing capacity,medium dense sand,}, volume = {18}, Number = {5}, pages = {143-153}, publisher = {Tarbiat Modares University}, title_fa = {تأثیر نسبت گیرداری بر روی رفتار فونداسیونهای باکتی تحت بارگذاری ترکیبی در ماسه}, abstract_fa ={صندوقه های مکشی به نحو گسترده ای در صنعت نفت و گاز استفاده می شدند. اخیراً فونداسیونهای باکتی به عنوان راه حل فونداسیون نوآورانه برای توربینهای بادی فراساحلی مدنظر قرار گرفته است. فونداسیونهای دامنه‌دار به نحو فزاینده-ای در طراحی سازه‌ها و تجهیزات توربین بادی فراساحلی برای تحمل شرایط بارگذاری ترکیبی قائم، افقی و لنگر استفاده می‌شود. در این پژوهش، الگوهای المان محدود سه بعدی فونداسیونهای باکتی در ماسه نیمه متراکم تحت بارگذاری ترکیبی تحلیل شده است. الگوهای عددی با مقایسه نتایج تحلیلهای المان محدود اعتبارسنجی شدند. تحلیلهای حساسیت در نسبتهای گیرداری ارتفاع به قطر باکت مختلف تحت بار ترکیبی با خروج از مرکزیتهای بار مختلف انجام گردید. پاسخهای بار ترکیبی از بار افقی خالص، لنگرهای واژگونی حاصل از ارتفاعهای برج گوناگون تا لنگر خالص مقایسه شد. نتایج تحلیل، چگونگی ارتباط و وابستگی ظرفیت باربری ترکیبی فونداسیونها را به نسبت گیرداری و شرایط بارگذاری بیان می‌دارد. حالتهای حدی نهایی به صورت ظرفیتهای نرمالیزه شده نشان داده شدند و روابطی از نتایج تحلیل ارائه گردید.}, keywords_fa = {فونداسیون باکتی,بارگذاری ترکیبی,تحلیل اجزای محدود,ظرفیت باربری,ماسه نیمه متراکم,}, url = {http://mcej.modares.ac.ir/article-16-14618-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-14618-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Ghoddousi, Parviz and Salehi, Amir Masou}, title = {Study of self-consolidating concrete robustness containing limestone powder based on rheological parameters}, abstract ={One of the major obstacles to development of self-consolidating concrete (SCC) on the industrial scale and various applications is the high sensitivity or very low robustness of this concrete to conventional concrete. From this, in the present study, a total of eight SCC mixes have been produced and their rehology parameters were tested. A control mix (C) was the initial target and, seven series of mixes were developed with variations of each of the principal properties (i.e. filling and passing ability and segregation resistance) or using of AEA and VMA admixture.In order to evaluate the robustness of each mixture, in addition to the mixture with amount of water content, four mixtures were made that the water content of each mix was changed ±3% and ±6% relative to the base water content and then the rheological properties of each mixture were determined. The rheology parameters (yield stress, plastic viscosity) values were determined by a coaxial rhometer. This automated rheometer is a rate-controlled rheometer that was employed to carry out rheological measurements 10 minutes after the initial contact between water and cement. It consists of a four-bladed vane that is immersed into the concrete and rotated at various speeds while the torque acting on the vane is measured. the objective of using rheology measurements is to provide scientific parameters that are capable of describing multiple aspects of workability. This fact are true especially for self consolidating concrete that has several properties in fresh state. So, it is required to perform several tests to evaluation of these properties that in addition to increase the quality control time, it also raises the costs and reduces the accuracy. Therefore, it seems logical to determine rheological parameters that are an accurate test with high sensitivity Instead of measuring multiple properties of fresh state through different workability tests for achieving to a proper robustness index for SCC. Therefore a good approximation of the fundamental rheological quantities for cement based material can be obtained in terms of yield stress (τ0) and plastic viscosity (μ). In this study a rheograph is defined as a graph that X axis is yield stress (τ0) and Y axis is plastic viscosity (μ). This graph that to that has been named “rheograph” is a convenient and essential tool to compare different concrete batches and examine the behavior relative to changed constituents, quantities of constituents, and/or relative to different times from water addition (and so forth). Thus rheograph is a systematical way to reveal the effects of slight decrease and increase in mixing water. The results of the study show that a slight increase in the amount of water increase the yeild stress of SCC, but decreasing water content in some concrete increase and in some concrete reduce the yeild stress. In contrast, in plastic viscosity of SCC, a slight decrease in the amount of water content increases the viscosity and a slight increase in the amount of water reduces the plastic viscosity of SCC. An appropriate index for estimating the robustness of SCC is the area enclosed between the rheological properties of concrete in changing the water content by ± 3% or ± 6%. According to this index, the addition of air entraining admixture to SCC improves robustness and reduces the amount of paste volume resulting in a severe reduction of robustness.}, Keywords = {Robustness of Self Consolidating Concrete,Slinght Change in Water Content,Rheology Properties,Rheograph,}, volume = {18}, Number = {5}, pages = {155-163}, publisher = {Tarbiat Modares University}, title_fa = {بررسی ابقاپذیری بتن های خودتراکم حاوی پودر سنگ آهک بر اساس پارامترهای رئولوژی}, abstract_fa ={یکی از موانع مهم توسعه بتن خودتراکم در مقیاس صنعتی و کاربردهای گوناگون، حساسیت بسیار زیاد یا ابقاپذیری بسیار کم این بتن در مقایسه با بتن معمولی می باشد. از این روی در تحقیق حاضر ابتدا 7 طرح مخلوط بر اساس یک طرح پایه با تغییر در نسبت های ترکیب و نیز افزودن افزودنی ها، تنظیم گردیده و مورد آزمایش هدفمند قرار گرفته اند. بدین ترتیب که هر کدام از 8 طرح مخلوط، در مقدار آب دقیق و نیز تغییر یافته به میزان 3±% و 6±% ساخته شده و سپس خواص رئولوژی هر مخلوط تعیین می گردد. نتایج این تحقیق نشان می دهد که یک شاخص مناسب برای بررسی ابقاپذیری بتن های خودتراکم، مساحت محصور بین خواص رئولوژی بتن ها در تغییر مقدار آب به میزان 3±% یا 6±% می باشد. بر اساس این شاخص، افزودن هوازا به بتن خودتراکم باعث بهبود ابقاپذیری و کاهش حجم خمیر باعث کاهش شدید ابقاپذیری می گردد.}, keywords_fa = {ابقاپذیری بتن خودتراکم,تغییر جزئی مقدار آب,خواص رئولوژی,رئوگراف,}, url = {http://mcej.modares.ac.ir/article-16-20256-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-20256-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Ghorbani, Ali and Salimzadehshooiili, Maysam}, title = {Stabilization of sandy soil using cement and RHA reinforced by Polypropylene fiber}, abstract ={Nowadays, cement is broadly applied to stabilize the soil to improve the mechanical and engineering properties of different soils and to control their deformations and swelling behavior. Nevertheless, due to the high expenses, civil engineers have always been trying to find an economic pozzolanic alternative for cement. In this regard, lots of construction materials such as fly ash, lime, blast furnace ash, pond ash, rice husk ash, etc are added to differentsoil materials to find an optimum replacement for the cement. Among the mentioned materials, rice husk ash (RHA), which is widely available in Guilan, Iran, is an environmentally dangerous material (if dumped in the nature). Hence, application of this material will be both economically and environmentally useful. Also, due to its high applicability, it can be easily applied in civil constructions. Hence, application of RHA in civil/construction projects will be considerably useful. On the other hand, different fibers (e.g. plastic, polyester, polypropylene, etc) are used for engineering purposes to both control the process of crack initiation and increase the material mechanical properties. the length of applied fibers, also, their percentage is two famous controlling parameters of applying fibers in soil stabilization programs. In this paper, a new soil stabilization method is introduced to stabilize Anzali sand using the combination of cement and RHA. Also, the possibility of cement replacement with RHA is investigated. Polypropylene fibers in 0.2 and 0.4 percentages are also added to the samples to control the growth of tensile cracks and to evaluate their effect on the compressive strength of stabilized samples. Hence, cement in 3, 5, 7.5, 10 percentages, also, RHA in 3, 5, 7.5, 10, 12 and 15 percentages are added to the sand samples to increase their compressive strength. Samples are cured for 28 days and unconfined compressive strength tests are conducted on the stabilized and reinforced samples. Based on the test results, compressive strength of all the samples were increase as cement and RHA percentages were increased. Also, RHA is introduced as a capable replacement additive for the cement. In order to make a generalization and provide a relationship for practitioners to use the results of the present study, different techniques can be adopted. Among them, artificial intelligence techniques are most in demanding ones. Neural networks, gen programming languages, genetic algorithms and evolutionary approaches can be applied to provide such relationships. In this paper, evolutionary approaches are considered and using evolutionary polynomial regression technique, simple predictive equation for forecasting UCS is proposed. In this regard, based on the results of conducted un-confined compressive strength tests, Evolutionary Polynomial Regression (EPR) technique is applied and a high accuracy predictive relationship for forecasting UCS of cement-RHA stabilized and polypropylene reinforced sand is presented (coefficient of determination of 94.4%). In addition, sensitivity analysis based on Cosine Amplitude Method (CAM) is carried out to investigate the most and the least effective materials on the compressive strength of samples. CAM analysis showed that although cement and RHA have meaningful effect on the determination of UCS, polypropylene percentage is the most sensitive additive controlling the variation of UCS.}, Keywords = {Sand,Rice husk ash,Polypropylene fiber,Uni-axial compressive strength,Evolutionary polynomial regression,}, volume = {18}, Number = {5}, pages = {165-176}, publisher = {Tarbiat Modares University}, title_fa = {تثبیت خاک ماسه ای با استفاده از سیمان و خاکستر پوسته برنج و مسلح شده توسط الیاف پلی پروپیلن}, abstract_fa ={در این مقاله روشی جدید جهت تثبیت ماسه انزلی با استفاده از خاکستر پوسته برنج و سیمان ارائه و امکان جایگزینی سیمان با خاکستر پوسته برنج بررسی شده است. در این راستا، سیمان و خاکستر پوسته برنج به ترتیب با درصدهای 3، 5، 7.5 و 10 (سیمان) و همچنین 3، 5، 7.5، 10، 12 و 15 (خاکستر پوسته برنج) به ماسه افزوده شده و تست های مقاومت فشاری تک محوری بر روی نمونه ها انجام شده است. همچنین با افزودن الیاف پلی پرولین با درصدهای مختلف 0,2% و 0,4%، اثر الیاف بر مقاومت فشاری تک محوری نمونه های تثبیتی بررسی شده است. بر اساس نتایج بدست آمده، سیمان و خاکستر پوسته برنج مقاومت فشاری نمونه ها را افزایش داده و جایگزینی نیمی از سیمان توسط خاکستر پوسته برنج ، سبب افزایش مقاومت فشاری می شود. با استفاده از رگرسیون چند متغیره تکامل یافته، رابطه ای با دقت بالا برای پیش بینی مقاومت فشاری ماسه تثبیتی با سیمان-خاکستر پوسته برنج و مسلح شده با الیاف پلی پروپیلن ارائه شده است.}, keywords_fa = {ماسه,خاکستر پوسته برنج,الیاف پلی پروپیلن,مقاومت فشاری تک محوری,رگرسیون چند متغیره تکاملی,}, url = {http://mcej.modares.ac.ir/article-16-15763-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15763-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Keramati, Mahdieh and Ayati, Bit}, title = {Petroleum wastewater treatment and optimization of effective parameters using electrocoagulation process}, abstract ={Petroleum is the major source of energy and the activities related to the petroleum industry leading to high volumes of wastewater and emissions different pollutants to water systems. According to studies, world oil demand will increase to about 107 million barrels a day over the next two decades, and about 32 percent of global energy will be provided from Petroleum by 2030. Thus wastewater resulting from oil and refinery industry is increasingly rising and discharges into the environment, which is a serious threat to the world's water resources. A large amount of water is used to extract and to refine the petroleum in oil refineries, thus produce the large amounts of wastewater. The wastewaters containing various kinds of pollutants with different concentrations are of environmental problems due to high organic load and hard-biodegradable compounds. With the increasing drinking water standards and environmental stricter regulations relation to discharge of sewage, electrochemical technologies have gained their importance all over the world during the last two decades and now electrochemical processes such as recovery of metals, electrocoagulation, electro-flotation and electro-oxidation can be effective technologies in the field of different wastewater treatment. In the electrocoagulation process by applying an electric current to the cathode and anode electrodes in a conductive solution by dissolving anode, coagulants produced in situ and cause the flocs is that they are floating with bubbles of hydrogen gas generated at the cathode. The metal ion generation takes place at the anode, while hydrogen gas is produced at the cathode. The metal ions form flocculates which trap contaminants while the hydrogen gas floats these particles. In this study, the electrocoagulation process was carried out with the use of a cathode and an anode made of stainless steel to reduce pollution from synthesis wastewater. For this purpose, the various parameters are optimized separately in this system by one factorial method, and then use experiment design methods. The effects of five parameters including the electrode surface, initial COD concentration, current density, pH and NaCl concentration were evaluated in the range of 23.36 to 78.36 cm2, 100 to 2500 mg/L, 2 to 30 mA/cm2, 3 to 11 and 0.3 to 2 g/L, respectively, in the case of electrocoagulation process. The optimum conditions of electrode surface, initial COD concentration, current density, pH and NaCl concentration were achieved 23.36 cm2, 900 mg/L, 20 mA/cm2, 8.5 and 0.5 g/L, respectively, for this process with energy consumption of 7.3 kWh/kg CODRem and electrode consumption of 0.4 Kg Fe/Kg CODRem during 60 minutes. The results of the experimental design of response surface methodology were confirmed the results of OFAT method with acceptable obtained error for the electrocoagulation processes. Based on results from experimental design of response surface methodology in this process, current density, time, pH and concentration of sodium chloride, respectively, were the most influential parameters. Electro-coagulation process seems to be an economic and environmental friendly process to remove the pollutants from wastewater. It has been demonstrated that electrocoagulation process with the use of stainless steel anode and cathode is a very effective and operative method to degrade Petroleum pollution and reduce COD.}, Keywords = {pH,COD,electrochemical,electrode surface,current intensity,COD.,}, volume = {18}, Number = {5}, pages = {177-187}, publisher = {Tarbiat Modares University}, title_fa = {تصفیه فاضلاب نفتی و بهینه سازی پارامترهای موثر با استفاده از فرایند الکتروکواگولاسیون}, abstract_fa ={با افزایش استانداردهای آب آشامیدنی و مقررات سخت‌گیرانه زیست‌محیطی در رابطه با تخلیه فاضلاب، تکنولوژی‌های الکتروشیمیایی در طول دو دهه گذشته اهمیت خود را در سراسر جهان به دست آورده‌اند و امروزه فرایندهای الکتروشیمیایی همچون بازیابی فلزات، انعقاد الکتریکی، شناورسازی الکتریکی و اکسیداسیون الکتریکی را می‌توان جزو فناوری‌های مؤثر در زمینه تصفیه فاضلاب‌های مختلف محسوب نمود. در روش الکتروکواگولاسیون با اعمال جریان الکتریکی به الکترودهای کاتد و آند در یک محلول رسانا با حل شدن آند، مواد منعقدکننده در محل تولید شده و موجب ایجاد لخته‌هایی می‌گردد که همراه با حباب‌های گاز هیدروژن تولیدی در کاتد شناور می‌شوند. در این پژوهش فرایند الکتروکواگولاسیون با استفاده از کاتدی و آندی از جنس فولاد زنگ نزن برای کاهش بار آلودگی از فاضلاب سنتزی انجام شد. در شرایط بهینه فرایند انعقاد الکتریکی با سطح الکترود cm2 36/23، غلظت ورودی mg/L900، دانسیته جریان الکتریکی mA/cm220، pHبرابر با 5/8 و غلظت سدیم کلرید g/L 5/0، 94 درصد حذف COD در مدت زمان 60 دقیقه با میزان مصرف انرژی مخصوص برابر باkWh/kg CODRem 3/7 و میزان انحلال آند فولادی kg Fe/kg CODRem 4/0 به دست آمد. براساس نتایج حاصل از طراحی آزمایش به روش سطح پاسخ در این فرایند دانسیته جریان الکتریکی، زمان، pH و غلظت کلرید سدیم به ترتیب تاثیرگذارترین پارامترها بودند.}, keywords_fa = {الکتروشیمی,سطح الکترود,شدت جریان,}, url = {http://mcej.modares.ac.ir/article-16-15530-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15530-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Pourzeynali, Saeid and Mobinipour, Seyed Ahm}, title = {Assessment of the probability of sidesway collapse of tall steel building with special moment resisting frame}, abstract ={In order to determine and predict the possible damage imposed on the structures, performance-based standards have presented certain levels and limits. The current study aimed to make a probabilistic evaluation of the process of the special steel moment frames exceeding these levels through comparing the demand measure (DM) and the intensity measure (IM). It further tried to examine the performance of the sixth and tenth issues of the national regulations and standard 2800 in confining the damage imposed on this type of structure. The results of DM probabilities analysis based on IM parameter could be expressed in two ways: 1) the fragility curve of the probability exceeding the limit states, and 2) assessment of the probability of the mean annual exceeding the limit states. Among numerous types of limit states, the global collapse of the structure is of utmost significance. The present study utilized both forms of this analysis. In the first phase of the research, cumulative distribution function curves (CDF) were used to assess the performance of the structures subjected to the records of various risk levels according to FEMA-350 guideline. To this end, a ten-story and a twenty-story special steel moment frame were modeled in OpenSees software. Then, fragility curves of frames collapse were drawn at three performance levels of immediate occupancy (IO), collapse prevention (CP), and global instability (GI) through using the incremental dynamic analysis (IDA) by means of the records introduced in The Next Generation Attenuation (NGA) for near and far fault records. Then, in the second phase of the study, the collapse probability of the structures under the study was estimated for Tehran city, which is located at a high seismicity zone. It is worth noting that these structures were designed and loaded according to the existing guidelines and were considered at the risk level 2 (risk level 2 according to the FEMA 356 and 360 guidelines) under the influence of the earthquake, Moreover, the median collapse capacity intensity (S ̂_CT) was calculated indicating the acceleration in which the structure collapse probability equals to 50%. Finally, the aforementioned curves were used and the probability values corresponding to the exceeding occurrence of the frames under the study were obtained from three risk levels with the return periods of 75, 475 and 2475 years old and the damage imposed on these frames were assessed and compared. The findings indicated that the special moment frames influenced by the far and near faults records were safe at the performance levels of IO, CP, and GI and hence, the purpose of the seismic designing and loading guidelines was fulfilled. The highest certainty coefficient belonged to the ten-story frame under the influence of far fault records and the lowest certainty coefficient belonged to the twenty-story structure under the influence of near fault records. This clearly demonstrated the influence of increasing the structure height on the collapse probability of the structures and the impact of near fault records. avbsbsb nncj nzzka naakk anaak kxlcl llajsj lsppddi aappais ppwwieu pkakanlssppd plssldj. opqpqqnznz llkksnx xm..nxmla l;aa;a ncmckc.}, Keywords = {Intensity Measure,Demand Measure,Earthquake hazard levels,Performance levels,Median collapse capacity intensity,}, volume = {18}, Number = {5}, pages = {189-202}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی احتمالاتی ظرفیت فروریزش جانبی ساختمان‌های بلند فولادی با قاب خمشی ویژه}, abstract_fa ={به‌منظور تعیین و پیش‌بینی میزان خسارت وارد برسازه‌ها استانداردهای مبتنی بر عملکرد، سطوح و حدود مشخصی را ارائه نموده‌اند. هدف از تحقیق حاضر ارزیابی این سطوح، با استفاده از مقایسه‌ی شاخص‌های تقاضای لرزه‌ای (DM) و شاخص شدت (IM)، و همچنین بررسی نحوه‌ی عملکرد مباحث ششم و دهم از مقررات ملی و استاندارد 2800 در محدود نمودن خسارت وارد برسازه‌ها است. بدین منظور با طراحی دو قاب خمشی فولادی ویژه ده و بیست طبقه و مدل‌سازی آن‌ها در نرم‌افزار OpenSees و انجام تحلیل دینامیکی افزایشی IDA با استفاده از رکوردهای معرفی‌شده توسط NGA برای حوزه‌های دور و نزدیک، منحنی‌های شکنندگی فروریزش قاب‌ها در سه سطح عملکردی IO،CP و GI رسم شده است. در ادامه با استفاده از منحنی‌های مزبور مقادیر احتمال متناظر با وقوع فرا گذشت قاب‌های موردمطالعه از 3 سطح خطر با دوره‌های بازگشت 75، 475 و 2475 ساله به‌دست‌آمده و به ارزیابی و مقایسه‌ی خسارت وارد بر این قاب‌ها پرداخته‌شده است. نتایج این تحقیق نشان می‌دهد به‌طورکلی قاب‌های خمشی ویژه موردمطالعه تحت اثر رکوردهای حوزه دور و نزدیک در سطوح عملکردی IO، CP و GI، ایمن بوده و بنابراین هدف آیین‌نامه‌های بارگذاری و طراحی لرزه‌ای تأمین‌شده است و بیشترین ضریب اطمینان را قاب ده طبقه و تحت اثر رکوردهای حوزه دور و کمترین ضریب اطمینان را سازه بیست طبقه و تحت اثر رکوردهای حوزه نزدیک دارد که این موضوع، علاوه بر ارائه تأثیر افزایش ارتفاع سازه بر احتمال فروریزش سازه‌ها، به‌وضوح اثر رکوردهای حوزه نزدیک را نیز نشان می‌دهد.}, keywords_fa = {شاخص شدت,شاخص تقاضا,سطوح خطر زلزله,سطوح عملکرد,مقدار میانه ظرفیت فروریزش,}, url = {http://mcej.modares.ac.ir/article-16-13549-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-13549-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {}, title = {}, abstract ={}, Keywords = {}, volume = {18}, Number = {5}, pages = {203-215}, publisher = {Tarbiat Modares University}, title_fa = {مطالعه آزمایشگاهی پدیده انتقال رسوب و مکانیسم ورود رسوبات به آبگیر در قوس 180 درجه با استفاده از روش تزریق رسوب روی بستر صلب}, abstract_fa ={در مقاله حاضر با استفاده از تزریق رسوب روی بستر صلب، به بررسی نحوه شکل‌گیری توپوگرافی بستر و مکانیسم ورود رسوبات به آبگیر در یک کانال قوسی U شکل پرداخته شد. بدین منظور یک دستگاه تزریق رسوب با نرخ یکنواخت و قابل تنظیم، طراحی و ساخته شد. بر اساس توصیه های محققین قبلی، آبگیر جانبی در موقعیت 115 درجه از این قوس و با زاویه انحراف 45 درجه نسبت به جریان نصب گردید. دستگاه تزریق رسوب در بالادست قوس مستقر گردید و نرخ رسوب تزریق شده برابر با ظرفیت انتقال رسوب جریان در مسیر مستقیم بالادست قوس در نظر گرفته شد تا هیچگونه رسوبگذاری در بالادست قوس انجام نشود. جهت تحلیل نتایج، میدان جریان حول آبگیر جانبی در قوس با استفاده از سرعت سنج سه بعدی ADV در حالت بستر صلب برداشت شد.  در این تحقیق اثر عدد فرود و دبی آبگیری بر پدیده انتقال رسوب در قوس و مکانیسم ورود رسوبات به آبگیر بررسی گردید. نتایج نشان داد به ازای اعداد فرود و دبی های آبگیری مختلف همواره پس از زمان تعادل یک پشته رسوبی در جداره داخلی نیمه اول قوس و یک پشته رسوبی دیگر در جداره داخلی نیمه دوم قوس و پایین دست آبگیر بوجود می آید اما با کاهش عدد فرود توسعه عرضی فرم های بستر بیشتر شده و ابعاد آنها نیز افزایش می یابد.}, keywords_fa = {انتقال رسوب, قوس 180 درجه, آبگیر جانبی, تزریق رسوب}, url = {http://mcej.modares.ac.ir/article-16-30223-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-30223-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Mehdipour, Vahid and Memarianfard, Mahs}, title = {Temporal Prediction of Tropospheric Ozone Considering Photochemical Precursors and Meteorological Parameters}, abstract ={Air pollution as a silent murderer of metropolitan areas demanded huge amounts of attractions. During the past few decades, after London 1954 black days, the world encountered a novel problem which was made by anthropologic actions. Scientific researches for scrutinizing the air pollution and its effects on humankind and the environment, started and improved after chronic influences of contaminations which in this era prognostication of pollutants and finding the relationships between parameters out, seems to be undeniable. Ozone as a tropospheric gas, has severe impacts on the all creatures while the human beings are more delicate in conjunction with this gas where it can destroy ability lungs and cause asthma and other pulmonary diseases. In the present article, the two most prevailing approaches for prediction, applied to the forecast tropospheric ozone value considering eight other photochemical precursors and meteorological parameters. Sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO) and particulate matters (PM2.5, PM10) as photochemical precursors, and also humidity, air temperature and wind speed as meteorological parameters, after data preparation, used for ground level ozone prognostication in Tehran, Iran, with a condensed population where suffers from severe air contaminations and high rate of daily death, related to the air pollution. Used data series, have been collected from 22 regions of the cited city during 2 years (2014 and 2015). Two evaluation criteria, root mean square error (RMSE) and correlation coefficient (R), selected for comparison of applications. Support vector machine (SVM) and artificial neural networks (ANN) as capable soft computing approaches which have been used in numerous areas of science, opted in this research. Support vector machine with classification of other eight parameters and by 286 vectors as a classifier and 97 border vectors, sorted the 70 percent of data sets as training and the residual amount of parameters used as testing data sets. Radial basis function (RBF) selected as Kernel function. Artificial neural network works as like as human brains and neurons between layers transfer datasets and process them during the run time, where in the recent paper the layer number of the created network is one for hidden layer and one for the output layer and 10 neurons have been selected for hidden layer and one for the output layer. Network type of this system is feed-forward with back propagation and TRAINLM used as training function and LEARNGDM used for adaption learning function. Both approaches depicted reliable and acceptable results, where RMSE and R values for support vector machine, respectively 0.0774 and 0.8456, also artificial neural network resulted 0.0914 for RMSE and 0.8396 for R, which are reasonable outcomes. As the outcomes for training datasets were better than the results for testing datasets, both approaches showed acceptable performances because of over-training controlling, which is a serious and prevalent difficulty of soft computers. Support vector machine, with lower root mean square error and higher correlation coefficient selected as better application for ground level ozone prediction. These series of studies are supportive for calibration of measuring systems and due to their expensiveness, soft computing is the most reliable and affordable substitute for the past machines. Also the analysis of tolerances among the parameters illustrated that CO, Temperature and NO2 are the most effective where, PM2.5 had the least amount impact on O3 forecasting process.}, Keywords = {Air pollution,Tropospheric ozone,soft computing,prediction,Tehran,}, volume = {18}, Number = {5}, pages = {217-226}, publisher = {Tarbiat Modares University}, title_fa = {پیشبینی سری زمانی مقدار ازن تروپوسفری با سازندهای فتوشیمیایی و عوامل هواشناسی}, abstract_fa ={روش‌های متداول اندازه گیری آلاینده‌های هوای دارای خطا، نیازمند فضای نسبتا بزرگ و صرف هزینه‌های بسیار کلان است، در حالی‌که می‌توان با استفاده از روش‌های جدیدی که توانایی یادگیری دارند از این معایب روش‌های معمول کاست. این روش‌ها که پایه ریاضی دارند و با استفاده از برنامه نویسی بنیان شده‌اند، هنوز به آن مرحله نرسیده‌اند که بتوان با اطمینان کامل جایگزین اندازه‌گیری‌های ماشینی شوند. در این مقاله از روش‌های شبکه عصبی مصنوعی و ماشین بردار پشتیبان که در تحقیقات گذشته نتایج قابل قبولی را برای موضوعات دیگر ارائه داده‌اند، استفاده شده است تا مقدار اوزن موجود در هوای سطح شهر تهران را با توجه به هشت پارامتر دیگر هواشناسی و آلاینده‌های معیار هوا، پیشبینی کند. در آخر با مقایسه عملکرد این دو روش با استفاده از دو معیار ارزیابی نتایج، نشان داده می‌شود که مقادیر R و RMSE برای ماشین بردار پشتیبان برابر است با 0.8456 و 0.0774 و برای شبکه عصبی مصنوعی 0.8396=R و 0.0914=RMSE ، که این نتایج حاکی از برتری روش ماشین بردار پشتیبان نسبت به شبکه عصبی است. البته هر دو روش برای این پیشبینی نتایج کاملاً مطلوب و رضایت بخشی ارائه داده‌اند. همچنین میزان تاثیرگذاری پارامترها بر روی ازن تحلیل شد که کربن منوکسید، دمای هوا و نیتروژن دی اکسید بیشترین تاثیر را بر روی تغییرات ازن داشتند درحالی‌که ذرات معلق هوا و بخصوص ذرات معلق با اندازه کمتر از 2.5 میکرومتر کمترین تاثیر را پیشبینی ازن داشتند..}, keywords_fa = {آلودگی هوا,ازن تروپوسفری,محاسبات نرم,پیشبینی آلاینده,}, url = {http://mcej.modares.ac.ir/article-16-13120-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-13120-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Nematzadeh, Mahdi and Poorhosein, Rez}, title = {Evaluation of compressive stress-strain behavior of RPC reinforced with steel and PVA fibers}, abstract ={Reactive powder concrete (RPC) represents a new generation of cement-based materials composed of cement, reactive ultrafine powders, siliceous fine aggregates, super plasticizers and fibers. Due to its microstructural properties, this concrete demonstrates specific properties including high compressive and flexural strength, superb durability. Since this is a novel type of concrete, a single design code containing multiple experimental results of high quality, together with reliable stress-strain models for the nonlinear analysis of the structural members made of this concrete type is lacking. Although some experimental equations to predict the strength of the RPC members can be found in the literature, note that there are shortcomings in the information provided specifically regarding the RPC containing synthetic and hybrid fibers. Hence, in this study, ten different mix designs of RPC, containing steel fibers at the volume fractions of 1, 2, and 3%, polyvinyl alcohol fibers at the volume fractions of 0.25, 0.5, and 0.75%, together with hybridizations of the two fiber types at the total fiber volume fraction of 1% were prepared, and then tested to obtain accurate and applicable equations as well as the compressive stress-strain curve with the purpose of estimating the mechanical properties and better predicting the behavior of this type of concrete. Then, the effect of the type and volume fraction of fibers, together with curing regime on the properties of RPC including the compressive strength, strain at peak stress, modulus of elasticity, and the shape of stress-strain curve was investigated. The obtained results indicate that as the volume fraction of steel and polyvinyl alcohol fibers increases, the compressive strength and strain at peak stress of the RPC specimens decreases; a trend which is also observed as the volume fraction of synthetic fibers in the concrete mix containing hybrid fibers increases.. The trend which is observed for the strain at peak stress in the RPC is very close to that for its compressive strength. The secant and tangential modulus of elasticity values of the RPC also demonstrate trends similar to each other, and the tangential modulus of elasticity in all the specimens has values higher than the corresponding secant modulus of elasticity. The RPC containing high volume fractions of steel fibers shows high modulus of elasticity values, due to the crimped shape of fibers as well as the strong cohesion they provide in the concrete. Heat treatment has a positive effect on the compressive strength and strain at peak stress of the RPC specimens, due to the acceleration of the hydration process of cementitious materials at high temperatures as well as the formation of a dense matrix. By using the nonlinear regression analysis of the data, experimental equations were developed for the parameters affecting the stress-strain curve of RPC. Finally, based on the experimental parameters obtained for all the RPC specimens, a model was proposed to predict the compressive stress-strain curve. By comparing the proposed model with the experimental results of the stress-strain curve of RPC, it can be said that the proposed model is capable of predicting the experimental results with a very good accuracy.}, Keywords = {Reactive Powder Concrete,Stress-strain diagrams,Fibers,Heat Treatment,}, volume = {18}, Number = {5}, pages = {227-238}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی رفتار تنش-کرنش فشاری بتن پودری واکنشی تقویت شده با الیاف فولادی و پلی‌وینیل الکل}, abstract_fa ={بتن پودری واکنشی نسل جدید مصالح بر پایه سیمان می‏باشد که به دلیل خصوصیات ریز ساختار آن دارای مقاومت بالا می‏باشد. از آنجا که این بتن نوظهور می‏باشد آیین نامه طراحی واحدی که دارای نتایج تجربی با کیفیت بالا به همراه مدل‏های تنش-کرنش قابل اعتماد برای تحلیل غیر خطی سازه‏ها باشد وجود ندارد. اگرچه تعدادی معادلات تجربی برای پیش‏بینی مقاومت اعضای ساخته شده از طریق این نوع بتن در ادبیات فنی موجود می‏باشد، اما باید در نظر داشت که این اطلاعات به خصوص در زمینه بتن پودری واکنشی حاوی الیاف سنتتیک و نیز ترکیب الیاف ها دارای نقص می‏باشد. از این رو، در این مقاله 10 طرح اختلاط از مخلوط بتن پودری واکنشی حاوی الیاف‏های فولادی، پلی وینیل الکل و ترکیب آنها در درصدهای حجمی متفاوت و با فرآیندهای مختلف عمل آوری ساخته شد و خصوصیات مکانیکی شامل مقاومت فشاری، کرنش در تنش حداکثر، مدول الاستیسیته، چقرمگی و انرژی جذب شده نسبی و نیز شکل منحنی تنش-کرنش مورد بررسی قرار گرفت. علاوه بر این، با توجه به نتایج آزمایشگاهی، روابط تجربی برای تخمین پارامترهای موثر در منحنی تنش-کرنش بتن پودری واکنشی ارائه شد. در نهایت، مدلی به منظور پیش بینی دقیق رابطه تنش-کرنش فشاری بتن پودری واکنشی پیشنهاد شد. نتایج نشان می دهد که مدل ‌پیشنهادی با دقت بسیار خوبی می‏تواند نتایج آزمایشگاهی را پیش‏بینی کند.}, keywords_fa = {بتن پودری واکنشی,منحنی تنش – کرنش,الیاف‌ها,عمل‌آوری گرمایی,}, url = {http://mcej.modares.ac.ir/article-16-20268-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-20268-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {Khabiri, MohammadMehdi}, title = {The correlation between the structure-traffic index and pavement performance in the rural roads}, abstract ={Layer structure of rural roads under heavy traffic has essential importance because of simultaneous observing of economic and technical issues. In this study with investigating a case study of a rural road, different structure models of layers a road under traffic Agricultural trailers have been investigated. To identify different models of the road of structure-traffic index (STI) is used. At first, it is specified that 12 wheels trailers with tridem axle have more destructive effect on the pavement relation to 18 wheels trailers with tandem axle, by the modeling of finite element software ABAQUS; and the Scania G400 placed for the base calculation as a critical trailer. Then different road models is investigated separate for fatigue and rutting distress under crossing of critical trailer. The modeling critical trailer load on the different road models show that there is a Exponential relationship between STI index and fatigue and rutting distress with acceptable accuracy. This relationship is indirect for the fatigue distress with changes constant equal to 13.76. In contrast, this relationship is direct for the rutting distress with changes constant equal to 135.31 that show rutting has more influence of STI index changes relation to fatigue. Also in this study, it is tried to investigate different layer efficiency of pavement in reducing agents related with rutting and fatigue damage that the most important matter is remarkable effect cold asphalt on the rutting reducing so that even cold asphalt layer is more effective to reduce rutting distress parameter relation to sub base and base layers with together. Layer structure of rural roads under heavy traffic has essential importance because of simultaneous observing of economic and technical issues. In this study with investigating a case study of a rural road, different structure models of layers a road under traffic Agricultural trailers have been investigated. To identify different models of the road of structure-traffic index (STI) is used. At first, it is specified that 12 wheels trailers with tridem axle have more destructive effect on the pavement relation to 18 wheels trailers with tandem axle, by the modeling of finite element software ABAQUS; and the Scania G400 placed for the base calculation as a critical trailer. Then different road models is investigated separate for fatigue and rutting distress under crossing of critical trailer. The modeling critical trailer load on the different road models show that there is a Exponential relationship between STI index and fatigue and rutting distress with acceptable accuracy. This relationship is indirect for the fatigue distress with changes constant equal to 13.76. In contrast, this relationship is direct for the rutting distress with changes constant equal to 135.31 that show rutting has more influence of STI index changes relation to fatigue. Also in this study, it is tried to investigate different layer efficiency of pavement in reducing agents related with rutting and fatigue damage that the most important matter is remarkable effect cold asphalt on the rutting reducing so that even cold asphalt layer is more effective to reduce rutting distress parameter relation to sub base and base layers with together.}, Keywords = {Agricultural trailers,rural roads,STI index,pavement performance,numerical modeling.,}, volume = {18}, Number = {5}, pages = {239-249}, publisher = {Tarbiat Modares University}, title_fa = {ارتباط بین شاخص ساختار-ترافیک و عملکرد روسازی‌ جاده‌های روستایی}, abstract_fa ={ساختار لایه‌ای جاده‌های روستایی تحت ترافیک سنگین به دلیل رعایت همزمان مسائل اقتصادی و فنی دارای اهمیت خاصی است. در این تحقیق با بررسی مطالعه موردی یک جاده روستایی، مدل‌های مختلف لایه‌ای یک جاده تحت عبور ترافیک تریلرهای کشاورزی بررسی شده است. برای شناسایی کردن مدل-های مختلف جاده از شاخص ساختار-ترافیک (STI ) استفاده شده است. مدل‌های مختلف جاده برای خرابی خستگی و شیارشدگی به صورت جداگانه در اثر عبور تریلر بحرانی بررسی شده است. با مدلسازی بارگذاری تریلر‌ بحرانی بر مدل‌های مختلف جاده مشخص شد که با دقت قابل قبولی، رابطه بین شاخص STI و خرابی‌های خستگی و شیارشدگی یک رابطه نمایی است.در مقایل این رابطه برای خرابی شیارشدگی به صورت مستقیم با ثابت تغییرات 31/135 است که این موضوع نشان‌دهنده تاثیرپذیری بیشتر خرابی شیارشدگی نسبت به خرابی خستگی در برابر تغییرات شاخص STI است. همچنین در این تحقیق سعی شده است به کارایی لایه‌های مختلف روسازی در کاهش پارامترهای خرابی شیارشدگی و خستگی پرداخته شود که مهمترین آن، تاثیر قابل ملاحظه لایه آسفالت سرد در کاهش خرابی شیارشدگی است به طوری که حتی لایه آسفالت سرد از مجموع دو لایه اساس و زیراساس، در کاهش پارامتر خرابی شیارشدگی موثرتر است.}, keywords_fa = {تریلرهای کشاورزی,جاده‌ روستایی,شاخص STI,عملکرد روسازی,مدلسازی عددی,}, url = {http://mcej.modares.ac.ir/article-16-15543-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15543-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} } @article{ author = {}, title = {An Economic Reliability-Based Seismic Design of Structures}, abstract ={The seismic design of the structures is subjected to uncertainties originating from various sources. To ensure that a safe design is achieved, the uncertainties must be considered in the seismic design process. The reliability-based seismic design is the proper approach that directly takes into account the uncertainties. In this approach the performance objectives are reliability-based seismic criteria expressed either in terms of an annual probability of exceeding a given performance level or in terms of a probability of exceeding a given performance level conditioned on the seismic intensity corresponding to a specific hazard level. It is obvious that the ultimate aim of the reliability-based seismic design of a building is not only to satisfy the reliability-based seismic criteria, but also to minimize initial or life-cycle cost. The reliability-based seismic design optimization (RBDO) is the method that achieves the most economic design satisfying the reliability-based seismic criteria (probabilistic constraints). However, the RBDO is less preferred. This is because to ensure that reliability-based seismic criteria are achieved, the statistics parameters of the seismic demand and capacity must be determined through the results of the nonlinear dynamic analyses. On the other hand, the use of the nonlinear dynamic analyses in the RBDO method can lead to the increase of the computational cost so that the personal computers require several years to run it. In this study, a method to produce the reliability-based economic seismic design is proposed. Reliability-based seismic criteria are expressed in terms of a mean annual probability of exceeding a given performance level. The main goals are to ensure satisfying the reliability-based seismic criteria through the use of the results of the incremental dynamic analyses and to produce the economic seismic design within reasonable computing time. The proposed method achieves the two goals through determining the optimum design of the force-based design method that satisfies the reliability-based seismic criteria. The optimum design of the force-based design method depends on the value of the response modification factor. The value of the response modification factor of a building, which leads to satisfying the reliability-based seismic criteria, is in the range of one to a maximum value. From an economic point of view, the desirable value of the response modification factor is the maximum one, which results in a minimum design base shear and accordingly in an economic design. In order to respond to the two main goals, the method aims to determine the maximum value of the response modification factor of a building so that leads to satisfying the reliability-based seismic criteria. The proposed method is used to produce the seismic design of a 4-story building for two reliability-based seismic criteria. The steel special moment resisting frame is considered as the lateral load resisting system in the studied building. The results reveal that the proposed method can efficiently produce the economic seismic designs satisfying the reliability-based seismic criteria within reasonable computing time.While the designed frame by Zacharenaki et al using existing RBDO method can not satisfy specifications of reliability and this is shown the ability and efficiency of the proposed method.}, Keywords = {Reliability-Based Seismic Design Optimization,Incremental Dynamic Analysis,Force-Based Design,Response Modification Factor,}, volume = {18}, Number = {5}, pages = {252-260}, publisher = {Tarbiat Modares University}, title_fa = {روشی جهت طرح لرزه ای اقتصادی مبتنی بر قابلیت اطمینان سازه ها}, abstract_fa ={بهینه سازی طرح لرزه ای مبتنی بر قابلیت اطمینان (RBDO) روشی است که در حضور عدم قطعیت ها با ارضاء کردن قیود احتمالاتی می تواند اقتصادی ترین طرح لرزه ای برآورده کننده سطح معینی از ایمنی را ارائه کند. جهت اطمینان از برآورده شدن قیود احتمالاتی نیاز است که پاسخ های سازه با استفاده از تحلیل های دینامیکی غیرخطی حاصل گردند. از سویی دیگر استفاده از تحلیل های دینامیکی غیرخطی در روش RBDO منجر به افزایش هزینه محاسباتی سازه می شود. در این تحقیق روشی جهت طرح لرزه ای اقتصادی مبتنی بر قابلیت اطمینان ارائه می شود. هدف روش پیشنهادی آن است که ضمن اطمینان از برآورده شدن قیود احتمالاتی از طریق بکارگیری تحلیل دینامیکی غیرخطی فزاینده، طرح لرزه ای اقتصادی را با هزینه محاسباتی معقول ارائه نماید. روش پیشنهادی از طریق تعیین طرح بهینه روش طراحی مبتنی بر نیرو (FBD) که ضوابط مبتنی بر قابلیت اطمینان را نیز ارضاء کند، بدنبال برآورده کردن اهداف مذکور می باشد. در روش FBD، طرح بهینه تابعی از مقدار ضریب رفتار است. روش پیشنهادی با تعیین ماکزیمم ضریب رفتار برآورده کننده قیود احتمالاتی، طرح بهینه ای از روش FBD که منجر به برآورده شدن ضوایط مبتنی بر قابلیت اطمینان می شود را ارائه می کند. بمنظور ارزیابی توانایی روش پیشنهادی، طرح لرزه ای سازه چهار طبقه با سیستم قاب خمشی ویژه با استفاده از این روش انجام شد. نتایج نشان داد که روش در ارائه طرح لرزه ای اقتصادی برآورده کننده ضوابط مبتنی بر قابلیت اطمینان موفق بوده است.}, keywords_fa = {بهینه سازی طرح لرزه ای مبتنی بر قابلیت اطمینان,تحلیل دینامیکی غیرخطی فزاینده,روش طراحی مبتنی بر نیرو,ضریب رفتار,}, url = {http://mcej.modares.ac.ir/article-16-16368-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-16368-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2018} }