@article{ author = {emami, ebrahim and Kheiroddin, Ali and Sharbatdar, mohamm}, title = {Investigation of Steel Curb Effect on Nonlinear Behaviour of Reinforced Concrete Frames With Finite Element Method}, abstract ={It is required to rehabilitate the existing structures due to many reasons including the retrofitting of damaged structures under earthquakes or the need to strengthen or retrofit an undamaged structure designed based on old building codes. So, the rehabilitation and retrofit of structures against seismic loads is unavoidable. This paper presents the results of a nonlinear finite element analysis of an ordinary reinforced concrete frame and also strengthened frame by steel prop and curb under monotonic lateral load. The effect of steel prop on linear and nonlinear behavior of reinforced concrete frame and also increasing the rigidity, ultimate strength, rate of energy absorption and ductility parameter of frame are investigated. The experimental results of a one-bay and one-story reinforced concrete frame are considered and after calibrating the numerical results against it, the mentioned parameters have been investigated. Numerical results show that using steel curb and prop box in compression and tension state with 5,7.5,10 cm2 area in frame will considerably increase the rigidity, ultimate strength and decrease the ultimate displacement of frame. Furthermore, the yielding of steel prop as a preliminary defensive system against lateral loads will increase the energy absorption and ductility and also will decrease the stresses in panel zone.}, Keywords = {Rehabilitation,RC frame,Steel Curb,Prop Box,Finite Element}, volume = {14}, Number = {3}, pages = {1-15}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-11187-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11187-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Ouhadi, Vahi}, title = {Lead Retention of Carbonated Kaolinite in the Adsorption and Electrokinetics Processes}, abstract ={Electrokinetics is a common and practical method for contaminant removal from fine grain soils. In spite of several researches performed on the factors affecting the application of electrokinetics method for contaminant removal from soils, there are still extensive attentions of researches on the influence of soil components on the efficiency of this method upon contaminant removal. The main objective of this research is to investigate on the impact of carbonate elimination and contaminant concentration on the Pb removal from carbonated kaolinite in electrokinetics process. To achieve this objective a natural kaolinite sample which had 4% natural carbonate and a carbonate eliminated kaolinite were laboratory contaminated with 5 and 20 cmol/kg-soil of lead nitrate. After achieving equilibrium, the laboratory contaminated samples were dried in oven at 40 centigrade temperature for 96 hours. Then, 27% water was added to samples as initial water content. To achieve homogeneous distribution of water content, the sample was kept in a plastic bag for 24 hours. Then sample was passed through #10 sieve to have a more homogeneous sample. Finally, the soil sample was compacted in five layers at dry density of 1.7 g/cm3 in the electrokinetics cell. Then, the electrokinetics method was performed on these samples for contaminant removal. Electrokinetics experiments performed for a 240 hours period. After the end of experiment, the soil sample was taken from cell and sectioned in 5 slides. Each slice was analyzed for water content, soluble and adsorbed contaminant. In addition to electrokinetics experiment, buffering capacity test was performed by titration of soil sample with nitric acid. For this purpose, the diluted nitric acid in 1:10 soil:acid solution was added to sample. The soil solution sample kept on the shaker for 96 hours. After equilibrium the pH of soil solution was measured. This experiment was performed for different concentration of nitric acid. The final type of experiment include batch equilibrium experiment in which different concentrations of 5, 10, 20, and 30 cmol/kg-soil of lead nitrate was prepared. Then 20 milligram of each solution was added to 2 grams of kaolinite sample. After the shaking period and centrifuging the sample, the pore fluid was analyzed to measure the soluble and retained heavy metal. The results of experimental study indicate that the reduction of carbonate in carbonate rich kaolinite and an increase in contaminant concentration causes a reduction in soil buffering capacity. This means that as the concentration of carbonate in soil sample decreases, one faces with a reduction in contaminant retention capacity of soil. In addition, in such a case a reduction in pH happens which consequently enhances the contaminant removal from soil. Furthermore, carbonate elimination causes an increase in contribution of electro-osmosis on soil improvement which is followed by water content variation and consolidation of soil.}, Keywords = {Electro-Osmosis,Electrokinetics,kaolinite,Carbonate,Contaminant Removal}, volume = {14}, Number = {3}, pages = {17-30}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-6710-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6710-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {1, 1 and Farsijani, Ali}, title = {The effect of moisture content on the shear strength parameters of plastic fine soils}, abstract ={The effect of matric suction on shear strength of soil, because of its dominant role in geotechnical modelling, has received the attention of researchers in this filed. This research is focused in investigating the effect of matric suction on shear strength of a fine soil. The physical properties of the soil are determined. All samples are passed through No. 200 sieve. The soil is a high plasticity soil which is classified CH according to the unified classification system. The filter paper method is performed to extract the soil water characteristic curve. In addition to its simplicity, one of the major advantages of this method is the vast range of suctions can be measured by it. Specimens were compacted at identical void ratio with different water contents. Suctions are inferred from empirical relations that relate the suction to the measured moisture content of filter paper which has been in contact with soil sample. Air entry suction is determined 140 kPa from SWCC curve. In order to examine moisture content effects on shear strength parameters (cohesion and friction angle) of the clay, soil samples are prepared with different moisture content and consequently different matric suctions with respect to soil water characteristic curve. The specimens with different initial moisture contents are statically compacted at dry density of 1.3 gr/cm3into direct shear test mould. The moisture contents of samples are in the range of 10 to 28 precent. Hence, according to soil water characteristic curve the initial matric suctions are between 42 to 25238 kPa. Direct shear tests are conducted in unsaturated state. After applying vertical stress the samples are left at least for 48 hours to allow the equalization of internal stresses. Based on experimental data the shear stress is plotted against horizontal displacement in different vertical stresses and moisture contents and the results and analysed and discussed. The effective stress equation proposed by Bishop (1959) is used to interpret the results. The effective stress parameter χ in each moisture content is calculated bythe equation suggested by Khalili & Khabbaz (1998) using the air entry suction extracted from SWCC curve. The results reveal that strength parameters do not substantially change at different moisture contents. The negligible changes in strength parameters may be attributed to slight changes in pore water pressure during shearing experiment. Such changes in pore pressure during shearing would be eliminated in constant suction consolidated drained experiments. The results of this paper support the validity of effective stress concept in unsaturated soils. In other words, with a proper estimate of effective stress, the saturated parameters are valid in unsaturated state and it is not necessary to measure strength parameters in unsaturated state. The unsaturated geotechnical experiments are time consuming and expensive and need special equipment and skills. The method proposed in this paper has a good degree of accuracy. Therefore it can decrease the costs of geotechnical investigation projects in arid lands.}, Keywords = {Initial water content,Cohesion,internal friction angle,plastic soil,filter paper method}, volume = {14}, Number = {3}, pages = {31-41}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-3446-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-3446-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Paseh, Hamidreza and Yazdani, Mahmood and Sharifzadeh, Mostaf}, title = {Evaluation and Improvement of Contact Detection Algorithms for Using in DEM in Rock Mechanics}, abstract ={Discrete Element Method (DEM) is a numerical method for computing the motion and effect of a large number of small particles. It is a very common method to solve rock mechanics problems, since it can solve problems containing particles in contact with complicated geometries efficiently. Contact detection is the most time consuming (so the most significant) part of DEM-based problem solving methods. In this article, authors, with the goal of implementing a numerical hydro-mechanical software to analyze and solve DEM rock mechanics problems (DA2), studied and investigated algorithms able to solve contact detection problem. The most algorithms designed to find contacts (contact detection algorithms), lie in two classes: 1) algorithms based on bounding boxes, and 2) algorithms based on hashing. The bounding box idea helps to simplify the contact detection problem and to prevent dealing with particle shapes by enveloping the whole particle in a shape (generally a rectangle or an ellipse) which is easy to check for finding overlaps. Since overlaps of bounding boxes may not directly result in contacts between particles, further checks are needed. In the former class, there are two well-known published algorithms, both based on sorting bounding boxes’ extents, able to find contacts between generally shaped particles in a fast and efficient way: incremental sorting and updating (ISU) algorithm, and double-ended spatial sorting (DESS) algorithm. Hashing algorithms are generally appropriate for particles with uniform sizes. Since rock mechanics problems mostly contain models constituted of blocks with non-uniform sizes, hashing algorithms are not utilized for solving them. In this article, ISU and DESS algorithms along with direct checking (DC) method are compared for their running time results to find the most appropriate (i.e. the fastest) algorithm to find contacts between rock blocks. For this purpose, algorithms were implemented by DA2 software, then, ran in the same environment and for same commonplace geomechanical problems with varying model parameters, like number of blocks, block size variation, angle of discontinuities and friction angle, and compared for their running time results. Results shows that ISU algorithm compared to DESS algorithm gives better/lower running time (ISU is at least twice as fast as DESS), i.e. more performance, and shows less sensitivity to model parameters. Also, ISU algorithm consumes less memory and it is simpler to implement. In the end, for further improvement of performance of ISU algorithm, delayed updating and parallelization solutions are offered. Delayed updating is a common way to optimize algorithms containing two phases of processing and updating. In order to apply delayed updating and parallelization to ISU algorithm, a solution is presented to separate sorting and updating phases of the algorithm. Then, parallelization is applied. Results show that using these techniques, can increase the performance of ISU algorithm by 20%.}, Keywords = {Rock Mechanics,Numerical analysis,Distinct Element Method,DA2 Software,Contact Detection Algorithm}, volume = {14}, Number = {3}, pages = {43-60}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-10641-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-10641-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Bavali, Moslem}, title = {Optimal Location of pile in Stabilization of Earth Slope}, abstract ={Stability analysis of earth slopes is among the major issues raised in geotechnical engineering which has involved so many researchers in different parts of the world. When stability of an earth slope is suspected, it is necessary to take preventive measures before instability happens. The first step to maintain the stability of an earth slope is performing excavation in the slope crest or/and filling in the slope toe. This is the cheapest way (model) for stabilization of earth slopes. If the model cannot provide the required factor of safety, it is necessary to use other stabilization methods. Numerical and laboratory methods are useful for modeling earth slopes stabilization. Modeling the stability of earth slopes using numerical methods is a common practice in geotechnical engineering. Moreover, stabilization of earth slopes using piles has been practiced by many researchers by using numerical and analytical methods. Although numerical and analytical methods have special capabilities, laboratory modeling is more reliable. Hence, it is discussed in this article. Stabilization of earth slopes with reinforced concrete piles is one of the important concerns of geotechnical engineering. Application of numerical and analytical methods to stabilization of earth slopes using piles is an issue commonly discussed by various researchers. Optimal location of concrete pile for stabilization of earth slope by means of numerical and analytical methods, has been practiced by various researchers. Their efforts have led to various results raising the question of what the optimal place for installation of a pile is. It seems that no experimental studies are conducted in this regard, which is discussed in this article. Experimental studies conducted in this article have the potential to solve the problem caused by varying and sometimes contradictory results of numerical analyses performed to find the optimal pile location. In this article, an experimental analysis of a homogeneous sand earth slope is conducted. The slope is saturated through precipitation and failure after loading by installing the reinforced concrete pile in different locations. All of the experimental tests were modeled and compared using the limit equilibrium (LE) and finite element (FE) methods, which are compliant with each other. The results obtained by experimental tests show the optimal location for installing reinforced concrete pile in a homogeneous sand slope for achieving the highest factor of safety and reduce costs of stabilization. In the present article, the optimal pile location for slope stabilization is determined by conducting laboratory studies of a layer sand slope saturated through precipitation. The resultant failure mechanism leads to acceptable results that help choose the optimal location for pile installation. The slope is stabilized by repeating the test and installing the pile in the optimal location, which is the best place to install the pile. The FE method (Plaxis software) and LE method were used to confirm the laboratory tests as well.}, Keywords = {Earth Slope,Concrete Pile,Optimal location,Stabilization}, volume = {14}, Number = {3}, pages = {61-69}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-6796-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6796-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {hoseinzadetabrizi, hamed and vaghefi, moham}, title = {Effect of Froude Number on flow pattern and scour around T-shaped spur dikes under submerged and unsubmerged condition}, abstract ={In this research parameters influencing flow pattern and scour around submerged and nonsubmerged series of spur dikes in straight channel were investigated. Scour pattern was investigated for three angles of dikes construction, and three submergence ratio.The result showed that with increasing Froude number and decreaseing submergence ratio, scour decreases. Also because of first spur dike effect on main flow, maximum scour depth in second and third spur dike is less than first one. The location of scour and ridge height change with Froude number, submergence ratio and angle.The three dimention velocity around spur dike were analyzed Then we used flow pattern to forecast scour pattern. In this research parameters influencing flow pattern and scour around submerged and nonsubmerged series of spur dikes in straight channel were investigated. Scour pattern was investigated for three angles of dikes construction, and three submergence ratio.The result showed that with increasing Froude number and decreaseing submergence ratio, scour decreases. Also because of first spur dike effect on main flow, maximum scour depth in second and third spur dike is less than first one. The location of scour and ridge height change with Froude number, submergence ratio and angle.The three dimention velocity around spur dike were analyzed Then we used flow pattern to forecast scour pattern. In this research parameters influencing flow pattern and scour around submerged and nonsubmerged series of spur dikes in straight channel were investigated. Scour pattern was investigated for three angles of dikes construction, and three submergence ratio.The result showed that with increasing Froude number and decreaseing submergence ratio, scour decreases. Also because of first spur dike effect on main flow, maximum scour depth in second and third spur dike is less than first one. The location of scour and ridge height change with Froude number, submergence ratio and angle.The three dimention velocity around spur dike were analyzed Then we used flow pattern to forecast scour pattern. In this research parameters influencing flow pattern and scour around submerged and nonsubmerged series of spur dikes in straight channel were investigated. Scour pattern was investigated for three angles of dikes construction, and three submergence ratio.The result showed that with increasing Froude number and decreaseing submergence ratio, scour decreases. Also because of first spur dike effect on main flow, maximum scour depth in second and third spur dike is less than first one. The location of scour and ridge height change with Froude number, submergence ratio and angle.The three dimention velocity around spur dike were analyzed Then we used flow pattern to forecast scour pattern. In this research parameters influencing flow pattern and scour around submerged and nonsubmerged series of spur dikes in straight channel were investigated. Scour pattern was investigated for three angles of dikes construction, and three submergence ratio.The result showed that with increasing Froude}, Keywords = {spur,T shape spur dikes,Froude number,submergence ratio,Flow pattern}, volume = {14}, Number = {3}, pages = {71-82}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-10811-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-10811-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {SadatLavasaniBozorg, Seyed Mohammad Ali and Ziari, Hasan and Divandari, Hasan and Izadi, Amir}, title = {In situ evaluation of modern methods for pavement layers density determination}, abstract ={Density is the best criterion in pavements quality control. Determination of asphalt mixture density while compaction and after that is an important issue from two aspects of compaction level measurement and the time of compaction process termination. The most common and accurate method of in situ density determination is core making. Common procedure is to use a core gear and performing density test on cores in laboratory. Being expensive, time consuming and unrepeatable test, besides causing pavement deterioration are disadvantages of core making. Time consuming causes layer weakness doesn’t discover soon enough to do some modifications on that. Nondestructive density tests became very popular in recent years. These tests don’t cause any deterioration on pavement surface and are more reach than core making and repeatable since are NDT which are divided to nuclear and non nuclear NDT tests. PQI 301 electromagnetic and Troxler (HS-5001EZ) nuclear devices field evaluation were done in this research. After statistical analysis it was resulted that PQI is convenience for asphalt layers and nuclear is convenience for granular layers.}, Keywords = {Density determination,Core making,Nuclear and Non Nuclear NDT methods}, volume = {14}, Number = {3}, pages = {83-92}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-7632-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7632-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {SoltaniMohammadi, Masoud and sepasi, mo}, title = {Modeling and Studying the Seismic Performance of Adjacent Reinforced Concrete Frames with Applying the Effect of Pounding}, abstract ={It is well known that the interaction between adjacent buildings with limited separation distance or in the other ‎words earthquake-induced structural pounding has considerable effect on seismic performance of buildings. Earthquake induced vibrations may cause impact between two adjacent buildings with inadequate separation distance. Pounding hazard is considerable particularly in populated residential regions because of the limited separation distance due to limitation of lands. This ‎phenomenon may result in substantial damage or even contributes to total structural collapse of structures. Major seismic events during the past decade such as those that have occurred in Northridge, Imperial Valley (May 18,1940), California (1994), Kobe, Japan (1995), Turkey (1999), Taiwan (1999) and Bhuj, Central Western India (2001) have continued to demonstrate the destructive power of earthquakes, with destruction of engineered buildings, bridges, industrial and port facilities as well as giving rise to great economic losses. Among the possible structural damages, seismic induced pounding has been commonly observed in several earthquakes. As the cost of land in cities increases, the need to build multistory buildings in close proximity to each other also increases. Sometimes, construction materials, other objects and any projections from a building may also decrease the spacing provided between the buildings. This leads to the problem of pounding of these closely placed buildings when responding to earthquake ground motion. The main purpose of this paper is the modeling of adjacent structures in order to study the effects of pounding. Among the existing models, nonlinear visco-elastic model has been selected for numerical simulation of pounding. To study the effect of pounding on seismic performance of reinforced concrete structures, two RC frames with 4 and 6 stories are selected and their seismic performance under pounding effects are numerically studied. The effect of storey and total height of structures, size of separation distance and mass of buildings in series on the impact has been investigated in adjacent RC frames. The selected frames have been designed according to direct displacement based design method in order to investigate the effect of impact on ductility demand and obtain a desired maximum induced displacement at a considered hazard level. Then by putting the structural models with different dynamic characteristics close together, the effect of altitude, size of gap, and story height on performance of two adjacent structures has been studied. The nonlinear time history analysis and incremental dynamic analysis (IDA) has been done to predict the seismic collapse capacity of systems. The results of analysis show that the effect of pounding severely depends on the phase difference of vibrations of adjacent structures. The phase difference itself, depends on mass, stiffness and seismic capacity of adjacent systems and the value of imposed plastic deformation as well. The effect of pounding in structural systems with the same height with little difference in initial periods is negligible, whereas the local effect of pounding especially in the case of floor to column impact is considerable.}, Keywords = {structural pounding,reinforced concrete frames,Seismic Performance,direct displacement-based design}, volume = {14}, Number = {3}, pages = {93-106}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-6201-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6201-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Ghoddousi, Parviz}, title = {Evaluation of yield stress and plastic viscosity of self-consolidating concrete mixtures containing stone powder using new concrete rheometer made for the first time in Iran}, abstract ={Self-consolidating concrete(SCC) application is using in the construction projects more and more because of its advantages include high quality and flow under its own weight without any vibration. The rheological properties of SCC are very important that it has a significant effect on mechanical properties and durability. In this study, using a special concrete rheometer that has made for the first time in Iran, rheological parameters of SCC are determined. For performance evaluation and calibration of device, standard oil with determined viscosity by factory is used. Plastic viscosity value obtained by rheometer was equal 2.208 Pa.S and the oil viscosity provided by the factory was 2.219. Therefore results show that Rheometer performance is according with design plan and rheological parameters can be determined well by this device. Also some experimental SCC mixture contains two kinds of powder as filler is made. The calculated values of plastic viscosity and yield stress of these mixtures show that SCC containing limestone powder to 200 kg/m3 indicating the best performance and with increasing the amount of filler to 300 kg/m3 cause to increase yield stress. Self-consolidating concrete(SCC) application is using in the construction projects more and more because of its advantages include high quality and flow under its own weight without any vibration. The rheological properties of SCC are very important that it has a significant effect on mechanical properties and durability. In this study, using a special concrete rheometer that has made for the first time in Iran, rheological parameters of SCC are determined. For performance evaluation and calibration of device, standard oil with determined viscosity by factory is used. Plastic viscosity value obtained by rheometer was equal 2.208 Pa.S and the oil viscosity provided by the factory was 2.219. Therefore results show that Rheometer performance is according with design plan and rheological parameters can be determined well by this device. Also some experimental SCC mixture contains two kinds of powder as filler is made. The calculated values of plastic viscosity and yield stress of these mixtures show that SCC containing limestone powder to 200 kg/m3 indicating the best performance and with increasing the amount of filler to 300 kg/m3 cause to increase yield stress. Self-consolidating concrete(SCC) application is using in the construction projects more and more because of its advantages include high quality and flow under its own weight without any vibration. The rheological properties of SCC are very important that it has a significant effect on mechanical properties and durability. In this study, using a special concrete rheometer that has made for the first time in Iran, rheological parameters of SCC are determined. For performance evaluation and calibration of device, standard oil with determined viscosity by factory is used. Plastic viscosity value obtained by rheometer was equal 2.208 Pa.S and the oil viscosity provided by the factory was 2.219}, Keywords = {Concrete rheometer,Yield stress,Plastic viscosity,Self-consolidating concrete,Bingham model}, volume = {14}, Number = {3}, pages = {107-115}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-1205-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1205-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Alaedini, Shohreh and KABIR, MOHAMMADZAMAN and Hejabi, Hadi}, title = {Performance of fiber reinforced polymers (FRPs) retrofitting used in RC frames}, abstract ={In the recent years, attempts have been made to prove effectiveness of FRPs in retrofitting/repairing of the reinforced concrete (RC) components. The use of fiber-reinforced polymers (FRP) to create composite concrete structures has increased in recent years. However, the seismic performance of RC structures retrofitted using FRP composites is yet to be scrutinized in terms of improving strength, ductility. This is of high importance if the retrofitted structures are to withstand higher seismic ground motions. The purpose of this study was to investigate the seismic performance of RC joint in frame structures under cyclic lateral loading. Analytical calculations using a finite element method (FEM) are presented for the strength, crack pattern; behavior of frames strengthened with layers of FRP and an experimental study of firth and third author of this paper is carried out to verify the mechanical properties of the proposed. The specimens were tested in a 3D test frame in structure laboratory of civil and environmental engineering department in AmirKabir University of Technology. Analytical models were investigated in LS-DYNA environment. Three test specimens were constructed and tested under cyclic lateral loading. Three-dimensional nonlinear finite element models for the RC frames were developed and simulated with the LS-DYNA finite element analysis (FEA) software. Three 1/3 scaled one-bay and one-storey. Frame designed was carried out based on ACI318 code. These specimens were typical as-built frames abstracted from the existing middle-rise residential buildings in Iran. Two specimens were reinforced by CFRP at the ends of beams, columns and at the joints; one specimen the other specimen was not reinforced and was used for comparison. The retrofitted specimens were built with different ways of wrapping FRP sheets at the frame’s joints and both ends of beams and columns. The wraps were provided to prevent the peeling of the laminates this was aimed to investigate the effective ways of strengthening and repairing of the frame by applying different directions of CFRP and GFRP fibers. The analytical models are used to assess the efficiency of the FRP composites rehabilitation by comparison between intact and retrofitted specimens. Specimens were reinforced by FRP at the ends of beams, columns and at the joints; one specimen was not reinforced and was used for comparison. Also, the effect of laminate architecture, arrangement and type of material was considered. For achieving this purpose eleven models were analyzed in finite element model. The Finite element analysis results indicated that the choice of the Fiber composite materials, the laminate and wraps arrangement and thickness affected the enhancement of the structural joint performance significantly. The results provide an important insight of the role of FRP sheets in improving the earthquake resistance of frame buildings. . Keywords: reinforced concrete; frame; FRP retrofit; Analytical; cyclic loading.}, Keywords = {FRP,. Keywords: reinforced concrete,Frame,FRP retrofit,analytical,Cyclic loading}, volume = {14}, Number = {3}, pages = {117-127}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-6535-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6535-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Kouchakzadeh, Mohammad and nasiri, FARZIN}, title = {Evaluation of the efficiency of using surface water simulation results to improve the accuracy of groundwater simulation in Silakhor shallow aquifer located in Lorestan province (Iran)}, abstract ={This paper evaluates the efficiency of using surface water simulation results to improve the accuracy of groundwater simulation due to improving the accuracy of its input boundary conditions. The three most important data sets of boundary conditions in groundwater flow simulation are groundwater recharge, evapotranspiration rates and their regional distributions that little information is usually available about them. Moreover, the incorrect definition of these values can lead to uncertain groundwater modeling that is not applicable for groundwater resources management. In the most of previous studies done in Iran, percentage of the average regional precipitation and the local pan evaporation data (available from local weather stations) are used as the regional groundwater recharge and evapotranspiration rates, respectively but they have high uncertainty in their quantities and spatial distributions. In this research in order to solve this problem, the values of groundwater recharge and evapotranspiration rates and their regional distributions, obtained from SWAT modeling results, were used as the related input boundary conditions data in groundwater flow simulation using MODFLOW model. SWAT model is a comprehensive watershed model that calculates these values in each Hydrologic Response Unit (HRU). The study aquifer in this research was Silakhor shallow aquifer with the area of 590 km2 located in Lorestan province of Iran. The annual water table depth in different locations of this aquifer had been reported from 0.75 to 40 meter. Using this approach for improving boundary conditions in groundwater simulation and its evaluation was carried out for first time in Iran. The SWAT model was run for a period of 7 years from 2002 to 2008. After calibration and verification of the model using hydrodynamic data of Silakhor and Tire-Doroud gauging stations, the values of groundwater recharge and evapotranspiration rates in each HRU were extracted. The MODFLOW model was run for the period of 9 months of 2009 using these simulated boundary conditions and the other required information. For comparison of the calculated values with the observed values of water table depths in the 20 piezometers for the period of 9 months of 2009, the Root Mean Square Error (RMSE) and Mean Absolute Errors (MAE) were obtained 1m and less than 1m, respectively. In continuous of this research, the values of 5, 10 and 15 percent of regional average precipitation and the evaporation data in Silakhor pan evaporation gauging station were used as usual boundary condition for groundwater simulation using the MODFLOW model. For comparison of the simulated values of water tables depths obtained from this usual approach with the observed ones, the both of RMSE and MAE values were calculated more than 1 meter. Therefore this research showed that using integrated SWAT-MODFLOW models was more applicable in the groundwater simulation in the study aquifer.}, Keywords = {SWAT model,MODFLOW model,Boundary condition,Silakhor plain aquifer}, volume = {14}, Number = {3}, pages = {129-138}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-865-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-865-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Massumi, Ali}, title = {Redundancy in RC Moment Resisting Frames II: Evaluating the Effects of Redundancy on Seismic Behavior}, abstract ={Structural redundancy is a non-independent concept in structural engineering and has inherent dependence on structural parameters such as overstrength and ductility, so that both of overstrength and ductility capacities should change corresponding to any variation in structural redundancy. Nevertheless, most of researchers notified that taking any increase in structural redundancy should be a desirable property to deal with more effectively against earthquake loading. Furthermore, this issue can reduce structural sensitivity to abnormal loads. In this research to clarify the pure role of redundancy in earthquake resistant design and to distinguish the role of redundancy from total overstrength capacity, a number of 3D reinforced concrete special moment resistant frames (RC-SMRF) with equal ultimate base shear coefficient were designed. The dynamic behavior parameters of the designed structures under natural strong ground motion were evaluated, especially with regards to configuration of nonlinear deformations. The analytical outputs obtained from analyzed structures are illustrated ensembles of maximum acceleration, maximum velocity and maximum drift of each story. Furthermore, adequacy and accuracy of response modification factor which should be assigned as general indicator of quality of total seismic behavior has been studied conceptually. The results of this research indicate that: (i) Assigning an increase in structural redundancy would not always lead to efficient improvement in structural seismic behavior. Furthermore, notification to process of increased redundancy should not be consider as a criterion for any basic improvement in structural performance. This issue means that it is better to consider the effects of redundancy on important seismic parameters such as both the structural member ductility and the overstrength capacity. (ii) The calculated response modification factors as mentioned in this research, can consider as an index of quality of structural dynamic performance which is corresponding to a certain level of redundancy. Accordingly, the above statement should be notified in general cases of those earthquake loadings which would cause a certain level of story drift. This certain level of story drift would denote the structural behavior typically follows the calculated response modification factor. Oppositely, if an earthquake loading causes more story drift from that assigned certain level, structural behavior typically does not follow the calculated response modification factor. (iii) The codified procedure of calculation of response modification factor which were discussed and assessed in this study, cannot be realized subjected to those input strong ground motions that able to display high amplitude and long period pulse or pulses in their velocity time history. It is important to know that strong near-fault ground motions often have an impulsive feature and impose large amounts of sudden intense kinematic energy which must be dissipated by structural system during a short period of time. This issue causes amplified deformation demands in structures which are associated with very few cycles of cumulative plastic deformations. Hence, the earthquake damages due to these seismic load cases are effectively related to maximum deformation as well as maximum ductility. Yet, structures cannot accomplish based on the calculated response modification factor in the mentioned cases.}, Keywords = {Redundancy,ductility,Seismic behavior,Nonlinear Incremental Dynamic Analysis}, volume = {14}, Number = {3}, pages = {139-152}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-11887-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11887-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {Hakimpour, Seyed Mehrab and Esmaeili, Mortez}, title = {Numerical Modeling effectiveness of Stone Column in Mitigation of Liquefaction During Earthquak}, abstract ={During recent earthquakes, it was observed that liquefaction can cause severe damages to several countries' infrastructures including the buildings, bridges, road and railways in the form of significant settlement and the relevant shear failures of subgrade soil. Amongst the various rehabilitation methods of the soils tending to be liquefied, utilization of the stone column have encountered with more attention because of its beneficial characteristics from both technical and economical points of view. One of the major issues in this matter is their efficiency in liquefaction mitigation in the single and group forms. For this purpose the current study has dedicated to numerical investigation of the problem of stone column efficiency in dissipating the excess pore water pressure during the earthquake excitation, and The reliability of the numerical modeling is verified via a centrifuge test results of VELACS project. a three dimensional analysis is carried out using FLAC3D. Also, effects of various parameters such as stone column diameter, stone columns distances on the liquefaction resistance of NEVADA sand soil are investigated.}, Keywords = {Liquefaction,Pore water pressure,Improvement,stone columns,Radial drainage}, volume = {14}, Number = {3}, pages = {153-204}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-11321-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11321-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {bahramiyarahmadi, mohamm}, title = {Bed topography variations in a 90° mild bend due to wedge-shaped spur dike}, abstract ={To control the outer bend of river from scour different structures such as spur dike, bendway weir and submerged vane can be used for modification of flow pattern. With interaction of these structures and water flow scour around structure occurs that is the main cause of their failures. It is assumed that the change of geometry and layout of structure can change bed topography for its stability and that is the purpose of the present study. Therefore, in this study a Triangle-shaped spur dike with different angles (23, 30, 40, 60 and 70 degrees) to the upstream direction under different hydraulic conditions (Froude numbers 0.194, 0.214, 0.233 and 0.253) was tested. For all experiments, single Triangle-shaped spur dike was installed outside bend of flume in 72° position which maximum scour depth is usually occurring. For all experiments, flow depth was kept constant equal to 13 cm. At the end of each experiment bed topography was measured and from that the scouring zone, maximum scour depth and distance of scour hole was computed. The results showed that the overall scour hole is created in toe of the spur dike that is expanded to the upstream and downstream structure. Triangle-shaped spur dike with 23 and 60 degree installation was found to create the minimum and maximum scour depth as well as its distance from the outer bank respectively. The maximum scour depth for spur dike with angles of 23 and 60° was measured to be 0.127 and 0.496 of the spur dike effective length respectively. In addition, the maximum scour depth distance of above mentioned angles from the outer bank was respectively, 0.743 and 1.6 the effective length of structure. Eroded sediments were deposited downstream the spur dike and point bars are developed. By increasing of spur dike angle, the point bars are formed away from the outer bank and extended in flume width. For spur dike angles of 23 and 70° the point bar distance from the outer bank was equal to 0.228 and 0.365 effective length of the structure respectively. To control the outer bend of river from scour different structures such as spur dike, bendway weir and submerged vane can be used for modification of flow pattern. With interaction of these structures and water flow scour around structure occurs that is the main cause of their failures. It is assumed that the change of geometry and layout of structure can change bed topography for its stability and that is the purpose of the present study. Therefore, in this study a Triangle-shaped spur dike with different angles (23, 30, 40, 60 and 70 degrees) to the upstream direction under different hydraulic conditions (Froude numbers 0.194, 0.214, 0.233 and 0.253) was tested. For all experiments, single Triangle-shaped spur dike was installed outside bend of flume in 72° position which maximum scour depth is usually occurring. For all experiments, flow depth was kept constant equal to 13 cm.}, Keywords = {Triangle-shaped spur dike,90° mild bend,scour and deposition}, volume = {14}, Number = {3}, pages = {165-175}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-11840-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11840-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {rezaiee-pajand, mohamm}, title = {shape optimization of concrete dams by three approximation methods}, abstract ={optimization of arch dams.}, Keywords = {arch dams,sequential quadratic programing,feasible direction,Sensitivity analysis}, volume = {14}, Number = {3}, pages = {177-188}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-9236-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9236-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} } @article{ author = {maadani, saeed and akbari, reaza and maalek, shahrokh}, title = {Comparison of the Vibrational Frequencies of RC Slab-on-Girder Bridge via Theoretical and Experimental methods}, abstract ={In this paper, the dynamic characteristics of two highway bridges have been extracted via performing several operational modal tests. The tests have been performed during the normal traffic passage and ambient condition. The first bridge studied here, the "Ziar-1" Bridge built in 2003s in the road between the cities of Isfahan and Ziar, is a two span reinforced concrete with cast in place slab-on-rectangular girder superstructure system with the total length of 33 m. The deck is simply supported over a wall type middle pier and two side abutments with closed type. The superstructure is supported by the piers and abutments through elastomeric bearings. The second bridge, the "Ziar-2" Bridge built in 2012s as the new line of that road, is a two span reinforced concrete with in-site slab-on-precast girder superstructure system with similar length of the first bridge. The deck of this bridge is continuous without middle or side expansion joints and is supported over a pier bent consisting of a bent cap and three circular columns. The bridges, which pass over the "Zayandeh-Rood" river, are structurally separate and a 50cm distance has been provided between them. Both the bridges have similar geometry but different boundary conditions. The results of the modal tests have been also compared with the results of supporting finite element models of the bridges and the effects of boundary conditions on the dynamic characteristics of the bridges have been investigated. At the time of the first phase experiments, the river was dry due to drought in recent years and the level of underground water was sufficiently deep. It is predicted that presence of water current around bridge piers, in which the superstructure have monolithic connection with piers and side abutments, may change the dynamic properties of superstructure. In order to investigate to what extent the presence of water current in the river may affect the dynamic characteristics of the bridges; additional modal test has been performed on the second bridge, in which its deck is continuously connected to the supporting elements. On the other hand, the seasonal effects of the water current in the river on the dynamic characteristics of one of the bridges, as representative of reinforced concrete slab-on-girder integral bridges, have been also studied. In order to realize to what extent the pier-superstructure connection in this bridge is monolithic, the actual displacement pattern of the measurement points on the superstructure at the pier location has been closely measured and compared with corresponding results of the finite element model of the bridge. The results show that, as far as the boundary conditions of the deck is concerned, it has significant effect on the dynamic behavior and corresponding natural frequencies of the superstructure, especially in the first bending and the first torsional modes. Also, it was found that the presence of water current around the piers of the bridge leads to slightly increase in the natural frequency and the associated damping values of the bridge.}, Keywords = {Dynamic characteristics,ambient vibration test,Boundary conditions,concrete bridges}, volume = {14}, Number = {3}, pages = {189-198}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-9942-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9942-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2014} }