@article{ author = {Attarzadeh, A. and Zarrati, A.R. and Shanehsazzadeh, A.}, title = {Flow Condition at Sudden Slope Change of Chutes}, abstract ={One of the important parts of many large dams is flood release chute spillway. Aerators are installed on chute spillways to prevent cavitation phenomenon under very high speed water flow. An aerator consists of a ramp providing a sudden slope change that separates water from the bed and permits air to mix with water. For the study of flow condition in aeration zone and for having an insight knowledge about the aeration, the study of flow condition on the ramp is a prerequisite. The change in the slope of the bed is common in spillways due to the change in the topographical slope and at the connection of the spillway and the stilling basin. In the present study, the flow condition at the place of sudden slope change was numerically simulated by FLUENT software. FLUENT is powerful software in simulation of water flow, in which the effects of turbulent are well considered. In this software, the Navier-Stokes equations are numerically solved. Volume of fluid method is applied to simulate the free surface water accurately. The results of the model in terms of pressure distribution at bed, pressure distribution in depth, velocity profile and water surface profile were compared with the results of an analytical model of streamline method as well as with the available experimental data. The analytical model is a streamline method based on conformal mapping with the basic assumption of ideal flow. The results of the model were compared in various slopes and water velocities. The study showed that numerical model can predict water surface profile and dynamic pressure properly and the results of numerical model are more accurate as compared to analytical model for the two important parameters of pressure distribution at the bed and the velocity profile. The pressure distribution was reasonably predicted by the numerical model at the bed of channel before the ramp for all the studied degrees and at the bed on the ramp for smaller degrees. The maximum error was nearly 5-10 percent. The velocity profile calculated by the numerical model was very close to the experimental data and the maximum error was nearly 5 percent. The analytical method was found quite capable in prediction of dynamic pressure and water surface profile, and less accurate in predicting the velocity profile. The study also showed that before and after the slope change, the influence length, where the dynamic pressures are significant, is dependent on the degree of sudden slope change and also on the amount of normal depth. Furthermore, the water surface profiles calculated by the numerical model and the analytical model were quite coincident, showing that the effects of gravity, viscosity and turbulence parameters on the water surface profile are insignificant.}, Keywords = {hydrodynamic pressure,Fluent,Fluent,Aeration ramp,chute,Sudden slope change,Numerical solution,Streamline method,Aerator}, volume = {12}, Number = {1}, pages = {0-0}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-930-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-930-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Omidbeigi, M. A. and Ayyoubzadeh, S. A. and SafarzadehGendeshmin, A.}, title = {Experimental and Numerical Study of Three Dimensional Flow Structure at Lateral Intake}, abstract ={The flow at a channel bifurcation is turbulent, highly three-dimensional (3D) and has many complex features. There is transverse motion accompanying the main flow and an extensive separation zone that develops in the branch channel. There are two complex flow regions along the intake channel: one is the separation zone and the other is the region in which helical motion of water particles forms. This separation occurs because the flow entering the branch channel has considerable momentum in the direction of the main channel flow. This zone causes hydraulic and sedimentation problems that must be known before designing the system. This necessitates a deeper insight into the flow patterns and shear stress distributions near the solid boundaries. In this research, 3D flow patterns at lateral diversion were investigated experimentally and numerically. The experimental investigation was carried out at a T-junction, formed by two channels with rectangular cross-sections. The width of lateral intake to the main channel was 0.4. 3D velocity measurements were obtained using Acoustic Doppler Velocimeter at junction region for 11%, 16% and 21% discharge ratios. Fluent mathematical model was then used to investigate the dividing open-channel flow characteristics. Turbulence was modeled by Two Equation (k-ε, k-ω) and Reynolds Stress (RSM) turbulence models. The predicted flow characteristics were validated using experimental data and the proper model was selected for hydrodynamic and parametric studies. Within the main channel, good agreement was obtained between all models prediction and the experimental measurements, but within the lateral channel, the RSM predictions were in better agreement with the measured data, and k-ω predictions was better than those of k-ε. The comparison of experimental and numerical streamlines at different elevations showed that the selected model is capable to simulate the most important features of flow at diversions. The study of the velocity contours at different elevations showed that the velocity magnitude decreases at main channel, just downstream corner of lateral intake at the near bed levels and this causes the sedimentation in movable beds. The results showed that the width of separation zone at lateral intake will decrease and the distance of dividing stream surface from left bank of the main channel will increase by increasing of the discharge ratio. Investigation of the flow pattern at the entrance of the lateral intake showed that the secondary flow will form at this section. The dimension of the secondary flow at near bed elevation will increase by increasing of the discharge ratio and this causes entering of more bed load into the lateral channel.}, Keywords = {secondary flow,Lateral intake,Experimental investigation,Fluent CFD model,Turbulence model}, volume = {12}, Number = {1}, pages = {0-0}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-9907-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9907-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Mohebbi, M. and Shakeri, K. and Majzoub, H.}, title = {Genetic Algorithm Based Approach for Optimal Design of Multiple Tuned Mass Dampers (MTMDs) under Earthquake Excitation}, abstract ={To improve the behavior of building structures subjected to lateral loads, such as wind and earthquake excitations, tuned mass damper (TMD) has been used extensively theoretically and experimentally in previous researches. To increase the effectiveness of TMD mechanism, different methods have been proposed to determine the optimal values of TMD parameters including its mass, stiffness and damping. In using single TMD on the structures subjected to external vibrations, the mistuning of TMD, variation of TMD damping and changes in structural dynamic characteristics cause significant reduction in the effectiveness of TMD. Multiple tuned mass dampers (MTMDs) have been proposed to overcome the shortcomings of single TMD where each TMD has different dynamic characteristics. Based on the results of different researches, it has been concluded that the performance of MTMDs is less sensitive to uncertainty of structural dynamic parameters than that of a single TMD. In the previous researches, for designing MTMDs on the linear structures subjected to various external excitations, several methods have been proposed based on different kinds of design criteria. In most of the proposed methods, to simplify the design procedure of MTMDs, some limitations such as identical masses and damping ratios for TMDs or uniform distribution for the frequency or damping of TMDs have been considered. Also these methods require extensive numerical analysis. To generalize the design problem of MTMDs, in this paper, an effective method has been proposed for optimal design of MTMDs on the multi-degree-offreedom linear structures subjected to any desired excitation. In this method, an optimization problem is defined for designing the optimal MTMDs. The minimization of the maximum displacement of structure is considered as objective function and the parameters of TMDs are considered as variables. Since the design problem includes a large number of variables, hence, in this paper, it has been decided to use Genetic Algorithm (GA) for solving the optimization problem. To illustrate the procedure of the proposed method and also to assess the effectiveness of MTMDs in improving the seismic behavior of structures, a ten–storey linear shear building frame was subjected to white noise excitation and for different values of TMDs mass ratio and TMDs number, optimal MTMDs were designed for minimizing the maximum displacement of structure. To focus on the main objective of this paper and avoid the complexity of the problem, TMDs were located on the top floor in parallel configuration. The results of numerical simulations showed the capability of GA in solving complex MTMDsdesign problem with a large number of variables as well as the simplicity of the method under any desired external excitation. Also it was concluded that increasing of the mass ratio of TMDs could improve the effectiveness of MTMDs. To assess the performance of optimal MTMDs under other earthquakes, which are different in characteristics with design record, optimal structure-MTMDs was tested under near-fault and far-fault earthquakes and the results have been reported.}, Keywords = {optimization,passive control,Tuned Mass Damper (TMD),Multiple Tuned Mass Damper (MTMD)}, volume = {12}, Number = {1}, pages = {0-0}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-1633-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1633-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Ghasemzadeh, H and AkbariJalalabad, E.}, title = {Computing the Compressive Strength of Cement Composite Reinforced with Carbon Nanotube Assuming Isotropic Behavior for CNT}, abstract ={For extraordinary properties of carbon nanotube (CNT), a lot of research has been done about its application to reinforce different materials such as electronic and building materials, and good effects of CNT have been observed. Experimental approach for determining the properties of composites containing fibers, especially carbon nanotubes, needs using of complex experimental methods and expensive laboratorial equipments. Theoretical approach can lower the cost of predicting properties of these composites. So, in this paper, an analytical relation is presented by continuum mechanics method to predict the compressive strength of cement composite reinforced with carbon nanotube. For simplicity of computations, carbon nanotubes were assumed to be isotropicand firstly oriented unidirectionally and uniformly in the cement composite. Representative Elementary Volume(REV), as anindicatorelement of this nanocompositeis, was chosen and analyzed by continuum mechanics method. A fiber embedded in a cylinder of cement with certain radius is named REV. The strains under loads were calculated and the stresses were obtained by Hook’s law. Then, for prediction failure of composite, von Mises’ yield criterion was applied and by that, the compressive strength of cement composite reinforced with unidirectionally oriented carbon nanotubes was obtained. For real cases, the results of this analysis should be generalized to cement composites reinforced with random orientation of nanotubes, since there is no control on the distribution of fibers in the laboratory and they are oriented randomly in composites, although researchers are studying on production of CNT/cement composites with arbitrary orientation of fibers.To apply the random orientation effect, Cox’s method was used. For this purpose, the fibers' distribution function f ( ) was assumed and it was observed that the random orientation of fibers reduces the effect of fiber reinforcing with respect to unidirectional orientation. Therefore, an orientation factor  1 was used considering random orientation in comparison with unidirectional orientation. As a suggestion, this factor can be experimentally obtained too. Experimental method was used to determine the orientation factor of fibers incomposites and good results were obtained. Then the presented analytical relationship was compared with experimental data. Matches and differences between the analytical method and the experimental data were studied and the suggestions were presented to lower the differences between the analytical and experimental methods. The effect of some parameters such as compressive strength of cement and the amount of carbon nanotubes added on the compressive strength of CNT/cement composite were obtained too. Accordingly that an ideal nanocomposite with regard to economical considerations can be obtained.}, Keywords = {Cement nanocomposite,Carbon nanotube (CNT),compressive strength,Representative Elementary Volume (REV),Isotropic behavior}, volume = {12}, Number = {1}, pages = {0-0}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-11008-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11008-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Azarhoosh, Z. and GhodratiAmiri, G. R. and Razeghi, H.R.}, title = {Response of Soil-Structure Systems Subjected to Forward Rupture Directivity Pulses}, abstract ={The combined effects of two major contributing factors, i.e. inertial soil-structure interaction (SSI) and near-fault ground motions, on structural responses were studied. Considering nearfault characteristics, soil-structure systems are subjected to both actual near-fault ground motion records and their dominant kinematic characteristics, i.e. forward rupture-directivity pulses, coherently travelling waves seen as a large amplitude and short duration pulse-type motion at the beginning of each fault-normal component of the record. As a result of the suitability of forward rupture-directivity pulses for quantifying the salient response features of structures, a mathematical model, proposed by Makris, was used to represent the forward rupture-directivity pulse-type motions. Using a comprehensive parametric study, the structure, a bilinear single degree of freedom (SDOF) system, the soil beneath the structure and a homogeneous elastic half-space were combined based on a discrete model to constitute the overall soil-structure model. The results have been presented in the form of elastic strength demand graphs for a wide range of non-dimensional key parameters, which describe the SSI effects. Both the soil-structure systems and the corresponding fixed-base structures were considered and compared. Using numerical time-stepping analyses, it was found that the response of soil-structure systems subjected to actual near-fault records is similar to those subjected to forward rupture-directivity pulses. Consequently, the forward rupture-directivity pulses can be used to predict the salient response features of soil-structure systems in seismically active regions. They can also be a realistic representation of near-fault ground motions for predicting the response of long-period structures. It was further observed that quite interestingly, the response of soil-structure systems subjected to actual near-fault records, has two maximum regions. However, it was recognized that further study would be required to clarify these regions. The results also indicated that considering SSI is critical for a variety of structures. Accordingly, underestimated near-fault responses could be obtained when the SSI effects are ignored.}, Keywords = {Soil-Structure Interaction,Near-Fault ground motions,Forward rupturedirectivity pulses,Elastic Response of Structures}, volume = {12}, Number = {1}, pages = {0-0}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-8964-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-8964-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Khatami, S.M. and Kheyroddin, A.}, title = {Investigation of Element Size Effect on the Nonlinear Behavior of Flanged Shear Walls}, abstract ={Completion and development of reliable analytical models using finite element method could help investigation and prediction of the actual structure response results. Analysis of each model in finite element software needs meshing, in which computer results are dependent specifically to geometry and dimensions of the elements, called "mesh dependence". Finding a strategy for independency of the results to meshing is tangible. For the mentioned purpose and also to investigate the role of finite elements meshing in flanged shear walls, finite element software was used. Different meshings of shear walls (tested by Vecchio and Palermo) were analyzed and studied. The results of analyses with different meshs showed different ultimate strengthes and lateral displacementes. Different shapes of mesh create various results, which are indicated in the finite element model. By increasing of the size of mesh, the final force was increased and the lateral displacement was decreased, which presents a rigid model. On the other hand, by decreasing of the dimension of mesh, a stiff model was seen. So, it is a need to create well proses to analyze and evaluate the flanged section of shear walls with finite element model. Getting suitable accuracy of finite element model, the mentioned concrete shear wall (vecchio and Palermo) was modeled by ANSYS. 3D SOLID65 element was employed for modeling of shear wall structures. This element is capable of cracking in tension and crushing in compression. In concrete applications, for instance, the solid capability of the element may be used to model the concrete while the rebar capability is available for modeling of reinforcement behavior. After calibration, optimum forms and dimensions are recommended. As an illustration, an idea was presented, by which flanged shear wall could be analyzed more carefully in ultimate strength and ductility. This analysis showed that the results of squared mesh are closer to the fact. For example, this type of meshing 6% error in ultimate strength and ductility in accordance to lab Specimen, presented the closer responses. Furthermore, investigation on the optimum size of the mesh showed that if the mesh has the same size of the thickness of the connecting element (Shear Wall Web), the results will have very high accuracy. For instance, squared meshes with same dimension of meshes equal to web thickness, rather than those with half dimension of that led to 1% of lateral resistance, which is closer to experimental test. It is possible that web thickness is 150 mm, thereby, we can use mesh sizes of 150mm, 75mm or 50mm. However, in order to obtain ultimate loads accurately, the mesh size of 150mm seems reasonable. Square meshes have four degrees of freedom. If the size of square is chosen to be the same as the web thickness, nodal forces induced in the web would be proportionate. For thischallenge, a flanged section reinforced concrete shear wall tested was selected to confirm the web thickness square theory. This shear wall was modeled by finite element program. The results of analysis showed accuracy in the investigated theory. In this study, the web thikness square theory has indicated 8% error in ultimate strength.}, Keywords = {Finite Element,Flanged shear wall,Element Size,Web Thickness Square,Mesh dependency}, volume = {12}, Number = {1}, pages = {0-0}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-2676-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2676-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Nasiri, A. and Mokhtarani, N. and Ganjidoust, H.}, title = {Post Treatment of Composting Leachate by Means of Ozonation and Granular Activated Carbon (GAC) Adsorption}, abstract ={There are different methods for treatment of composting leachate. Parameters dictating which method to be chosen include quantity and quality of the leachate, required amount of treatment and economical issues. Integration of ozonation and GAC adsorption into a single process is one of the attractive methods for post treatment of wastewater. Therefore, post treatment of composting leachate by means of ozonation and granular activated carbon (GAC) adsorption was considered as the main objective of this study. This study was conducted in laboratory scale and in batch mode. The set-up of batch system consisted of a Plexiglas column with 20 mm inner diameter and 800 mm height. The tall height of the column provides the required contact time between ozone and pollutants. Ozone was supplied to the column through a diffuser sited at its bottom. The outlet gas of the reactor may contain some residual ozone and can cause air pollution. Therefore, it is dangerous for the people working nearby the reactor. Thus, the ozone in the gas phase leaving the column was removed by KI solution. All experiments were conducted at room temperature (24 ±2°C). The leachate used in this study was obtained from the effluent of the Leachate Treatment Plant of Rasht Composting Facility (Guilan, Iran). All the chemicals employed for analysis were analytical grade and obtained from the reliable companies. In order to conduct the experiments, after complete determination of the specifications of GAC as an adsorbent, different dosages of GAC were added to 800 mL of leachate with the given initial concentration and pH in the column. The pH value of the solution was adjusted by Sulfuric Acid or Sodium Hydroxide as needed. Then the ozone gas was introduced into the column and the samples were taken in different intervals of time. After that required parameters of the samples were measured. Ozone generator (ARDA-COG 5S) with 5 gr/hr nominal capacity was used to produce ozone gas from pure and dry oxygen. Before starting each step of the experiment, the ozone generator was calibrated for ozone concentration. Pressure and flow rate of ozone gas produced was equal to 2 bara and 1 liter per minute, respectively. The results showed that integrated treatment of the leachate with ozonation and activated carbon adsorption, namely catalytic ozonation, was more effective than each process solely. In this study, COD removal rate of 44% in adsorption process, 57% in ozonation process and 80% in integrated process was achieved after 60 minutes. According to the results, in the integrated process, addition of the adsorbent (as long as it floats in the leachate) has positiveeffect on the removal of organic load. The pH value is another important parameter that affects the removal rate in the integrated process. It was found that removal of organic load is more evident at basic condition than at acidic condition. In this study, the maximum COD removal was achieved in the pH values between 8 and 9. Furthermore, in this process, ozonation along with adsorption process resulted in reactivation of activated carbon and avoided frequent GAC regeneration. After 5 times of the reuse of virgin GAC through a consecutive experiment, only 7% loss in COD removal was observed in the integrated process, while it reached to 95% for single adsorption process at the same condition. This can be explained either by the predominance of catalytic reactions rather than adsorptionoxidation reaction in the process or to the in situ regeneration of GAC.}, Keywords = {leachate,Ozonation,Granular activated carbon,Adsorption,compost}, volume = {12}, Number = {1}, pages = {0-0}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-2317-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2317-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Jalali, A.R. and Yasrebinia, Y.}, title = {Investigation of Steel Welded Moment Connections Performance under Column Collapse}, abstract ={Progressive collapse of buildings has raised questions on adequacy of the existing regulations to prevent local and, in turn, global collapses. The present study mostly focuses on the performance of welded moment connections against progressive collapse. The performance of moment connections suggested in the FEMA 350, which are proper for seismic forces, Welded Flange Plate (WFP), Reduced Beam Seaction (RBS), Welded Unreinforced Flange- Welded Web (WUF-W) and Free Flange (FF), has been studied. The models used include non-linear behavior of materials and geometrical nonlinear behavior. The behavior of steel materials used in the structure is the true behavior of steel was stress-strain, which has been considered in the model completely. The nonlinear stress-strain behavior of steel selected for modeling the real behavior of beam and column members in the structure. The material properties of all steel components were modeled using elastic-plastic material model from ABAQUS. For connection region porous material plasticity was used. The diagram of vertical force against vertical displacement for each connection was drawn, and the state of each connection failure was investigated. Making the large scale experimental models to study the progressive collapse of structures seems too difficult. Using finite element models to study the behavior of structures are relatively appropriate option with regard to time and cost. In all of the numerical models, shell (S4) element has been used to simulate the beams, columns and connections. This is a four-node element, which contains four integration points on the element. During the calculations, full integration method with more precision was used. For analysis of the models, dynamic explicit method was used. This method is suitable to analyze the models with more members having nonlinear characteristics of materials and large deformations. In this method, the central difference integrating is used to solve the dynamic equations. In every time step, this method performs simpler than other methods in solving dynamic equations since there is no need to inverse stiffness matrix in any time stage. The used numerical method has compared using the laboratorial results, which have tested in 2010 by NIST. The analytical results showed a good agreement with laboratory models. The results of numerical analyses illustrated that RBS connection has less strength in comparison with other connections and this connection reaches maximum vertical displacement with less force. Performance of FF and WUF-W connections is similar to each other. These connections more resistant in comparison with RBS. WFP connection is more resistant as compared with the WUF-W, FF and RBS connections against the failure of the column. Failure load in WFPconnection is twice of other connection, and according to the analytical results, this connection is suitable for HLOP structures. In all connections, rotation capacity corresponding to collapse prevention against column removal scenario is about twice of the accepted criteria that FEMA 350 has suggested for seismic loads.}, Keywords = {Moment frame,Explicit Dynamic Analysis,Ductile fracture,large deformation,Material Nonlinearity}, volume = {12}, Number = {1}, pages = {0-0}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-1961-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1961-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Garivani, S. and Aghakouchek, A. A. and SoltaniMohammadi, M.}, title = {Effects of Masonry Infills on Seismic Behavior of Steel Frames with Khoreeni Connections and Their Elements}, abstract ={Steel frames with Khorjeeni connections have been widely used in the traditional construction of buildings in Iran during the past decades. In the traditional form of Khorjeeni connections, double section beams are not cut at the intersection with columns, rather they are connected to the column by means of two angles places over the top and bottom of the beam flanges. This type of connection offers advantages for frames, wich carry gravity loads, but it has deficiencies when the frames are subjected to lateral loads. Like other structural frames, there are masonry infills in many frames with Khorjeeni connections. The behavior of composite frames subject to lateral loads differs from that of bare steel frames. In this paper, positive and negative effects of masonry infills were studied on the behavior of steel frames with Khorjeeni connections. Finite element method was used to carry out nonlinear static analysis of subassemblages of this type of frames. Initially, the results of some experiments were utilized to verify the details of the model. Then numerical models of toe span or four span frames with different configuration of bracings and masonry infills were studied. The results showed that infill frames increase the stiffness and strength of frames in the absence of bracing considerably. Even when bracings are present, the increase in stiffness and strength is significant. Simplified compressive strut models proposed in recent guidelines for seismic rehabilitation of existing buildings are also utilized to analyze the models. The results show agreement with the results of more sophisticated FE models. The masonry infills, however, have some negative effects on the behavior of Khorjeeni frames. Parts of the column in the vicinity of connections are prone to plastic damage, particularly when the infills are relatively strong. The Khorjeeni connections are subjected to vertical forces and tortional moments. Due to limited vertical strength of these connections, top stories of this type of frames may suffer when compressive action of strut is mobilized for other bays. This action introduces additional moments, which may damage the connections. Therefore, considering of these negative effects of infills is very important when seismic behavior of the existing frames is assessed, because these effects limit the interstorey drift ratios.}, Keywords = {Masonry infill,Khourjeeni connection,Stiffness and ultimate strength of composite frames}, volume = {12}, Number = {1}, pages = {0-0}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-1632-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1632-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Sabbagh-Yazdi, S.R. and Rezaei-Manizani, H.}, title = {Using Depth Average Flow Solver of NASIR Finite Volume Software for Modeling Air Entrainment from Water Surface in Chute Flow}, abstract ={In this paper, the results of water flow modeling and computation of air distribution in chute spillways are described. The depth average flow solver of NASIR finite volume software was utilized for modeling of water flow in chute spillways. In this module, the shallow water equations modified for steep slopes are solved using cell-centre and cell-vertex schemes of finite volume method that suits unstructured triangular meshes. Using the computed velocity components and flow depth at each nodal point, the air entertainment parameters (air inception point, mean air concentration and vertical distribution of air concentration) are calculated by utilizing some empirical relations. The empirical relations for the air concentration were adopted by the pervious researchers using the measurements on large scale flow in chute spillways. In the present work, three modeling strategies were performed: 1) Solution of flow field and then calculation of air concentration parameter (as a post-processing operation after convergence of the water flow solution), 2) Coupled solution of the flow equations and air concentration relations considering the flow bulking and reduction of global friction parameters due to air entrainment and 3) Adding the air entrainment on density variation effects to the coupled solution of the flow equations and air concentration relations considering the flow bulking and reduction of global friction parameters due to air entrainment. In order to assess the quality of the results of the three modeling strategies, the readily available flow velocity and air concentration measurements on AVIMORE chute spillway were used for comparison considering the best experimental relations for simulating the entrainment of air into the flow on chute spillways. In order to provide better understanding of the velocity and air concentration, the vertical distribution profiles of these parameters were plotted from the multi-layer treatments of depth averaged computed results. Comparison of the computed velocity fields and air concentrations with the reported field measurements at the stations 503 and 505 of AVIEMORE chute spillway presents promising agreements. However, the accuracy of the 2nd and 3rd modeling strategies (in which the coupled solutions of water flow equations and air concentration relations are considered and the effect of air content on the reduction of global friction of the water flow is taken into consideration) was much better than that of the 1st modeling strategy (in which the air concentration relations are considered as post processing on water flow equation solution for depth and velocity fields). Furthermore, no significant differences were observed between the results of the 2nd and 3rd modeling strategies. Hence, it can be concluded that the effect of air concentration on density variation of the supercritical water flow does not play an important role on the results of the coupled solutions of water flow equations and air concentration relations.}, Keywords = {Modeling chute spillway flow,Vertical distribution of air entrainment from water surface,SWE for steep slope}, volume = {12}, Number = {1}, pages = {0-0}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-163-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-163-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Garivani, Sadegh and Aghakouchek, Ali and SoltaniMohammadi, Masou}, title = {Effects of strengthening the masonry infills by reinforced shotcrete on seismic behavior of steel frames with Khoureeni connections and their elements}, abstract ={A large number of buildings in Iran are constructed with masonry infills for functional and architectural reasons. Often, engineers do not consider masonry infill walls in the design process because the final distribution of these elements may be unknown to them, or because masonry walls are regarded as non-structural elements. However, infill walls tend to interact with the frame when the structure is subjected to lateral loads. Masonry infills contribute to the stiffness of the infilled frame under the action of lateral load. This leads to structural response deviating from what is expected in the design. The effects of the infills on the seismic behavior of buildings may be positive or negative, depending on a large number of parameters. Steel frames with Khorjeeni connections have been widely used in the traditional construction of buildings in Iran during the past decades. In the traditional form of Khorjeeni connections, double section beams are not cut at the intersection with columns, rather they are connected to the column by means of two angles places over the top and bottom of the beam flanges. This type of connection offers advantages for frames, wich carry gravity loads, but it has deficiencies when the frames are subjected to lateral loads. Like other structural frames, there are masonry infills in many frames with Khorjeeni connections. The behavior of composite frames subject to lateral loads differs from that of bare steel frames. In this paper, positive and negative effects of masonry infills were studied on the behavior of steel frames with Khorjeeni connections. Finite element method was used to carry out nonlinear static analysis of subassemblages of this type of frames. Initially, the results of some experiments were utilized to verify the details of the model. Then numerical models of toe span or four span frames with different configuration of bracings and masonry infills were studied. The results showed that infill frames increase the stiffness and strength of frames in the absence of bracing considerably. Even when bracings are present, the increase in stiffness and strength is significant. Simplified compressive strut models proposed in recent guidelines for seismic rehabilitation of existing buildings are also utilized to analyze the models. The results show agreement with the results of more sophisticated FE models. The masonry infills, however, have some negative effects on the behavior of Khorjeeni frames. Parts of the column in the vicinity of connections are prone to plastic damage, particularly when the infills are relatively strong. The Khorjeeni connections are subjected to vertical forces and tortional moments. Due to limited vertical strength of these connections, top stories of this type of frames may suffer when compressive action of strut is mobilized for other bays. This action introduces additional moments, which may damage the connections. Therefore, considering of these negative effects of infills is very important when seismic behavior of the existing frames is assessed, because these effects limit the interstorey drift ratios.}, Keywords = {Khourjini connection,Masonary infill,Reinforced shotcrete,Stiffness and ultimate strength of infilled frame}, volume = {12}, Number = {1}, pages = {1-10}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-10517-en.html}, eprint = {}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Ouhadi1, V.R. and Omidi2, A. H. and Goodarzi, A.R}, title = {Application of EDTA for Remediation of Pb Contaminated Bentonite by the Use of Soil Washing Method}, abstract ={The remediation of heavy metal contaminated soils is one of the known challenges of researches in many industrial countries. The use of EDTA (Na2EDTA.2H2O) is one of the common soil-washing methods. In spite of several research conducted on this subject, the optimization of the use of EDTA for heavy metal removal from contaminated soils, specifically soils with relatively high surface area, are not well addressed in the literature.  The main objective of this research is to evaluate the optimization of the use of EDTA in remediation of Pb-contaminated bentonite. To achieve the above mentioned objective, bentonite samples were laboratory contaminated with different concentrations of lead nitrate. Lead nitrate at concentrations of 0.001, 0.005, 0.01, 0.5 and 0.7 mol/l (1, 5, 10, 50 and 70 cmol/kg-soil) was used to laboratory contaminate bentonite. After drying the contaminated samples, they were exposed to different concentrations of EDTA. EDTA at concentrations of 0.001, 0.005, 0.01, 0.05, and 0.1 mol/l (1, 5, 10, 50, and 100 cmol/kg-soil) was used in 1:10 soil:electrolyte ratio in accordance to EPA. For sample preparation, 20 ml of EDTA at the required concentration was added to 2 grams of a dried contaminated bentonite. Samples were shaken for 2 hours on a horizontal shaker. Then, they were kept for 96 hours to reach equilibrium. In these 96 hours of equilibrium, soil samples in centrifuge tubes were shaken 2 hours in each 24 hours. Finally, samples were centrifuged with 4000 rpm to separate the solid and electrolyte. Then, the efficiency of Pb removal from samples was measured by analyzing the electrolyte. It should be emphasized that to prevent precipitation of lead ions in electrolyte, nitric acid was added to electrolyte to keep the pH less than 2. The achieved results show that the quantity of removed Pb ions by the application of EDTA is relatively equal to the concentration of applied EDTA. In other words, as the 1 , the quantity of lead removal by EDTA is equal to EDTA concentration. This quantity of lead removal is neither a function of lead concentration nor to the number of soil washing by EDTA. In addition, since the quantity of removed Pb is only a function of EDTA/Pb ratio, therefore such a removal is not dependent to the pH variations caused by different concentrations of Pb or EDTA. This approves that the high buffering capacity of bentonite in comparison to other variables of environment has the minimum impact on the interaction process of EDTA and heavy metal contaminated bentonite.}, Keywords = {EDTA,EDTA,Bentonite,Pb,Soil remediation}, volume = {12}, Number = {2}, pages = {1-9}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-4083-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-4083-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Khaji, Naser and Arab, Mohammad Hossei}, title = {Seismic analysis of baffled liquid storage tanks using boundary element method}, abstract ={Nowadays, fluid storage tanks are as important as fluids in urban life. The dynamic behavior of this important structure is different from common structures. Baffles as a passive control device can reduce the effects of sloshing which reduces the structural response to seismic excitation. In this study, the effect of baffles on seismic response of cylindrical vertical liquid storage tanks is investigated. The considered baffle is an annular plate with constant level from the base and constant inner diameter fixed on wall of the tank. Considering Laplace equation as the governing equation of fluid domain, and using boundary element method, a rigid tank is analyzed in the frequency and time domains. Afterwards, the baffle effects on natural frequency (in the frequency domain), and on base shear and overturning moment (in the time domain) due to El Centro and Erzincan earthquakes are investigated. Based on the results of mentioned analyses, it is observed that when the baffle is installed, the natural frequency of liquid domain reduces. Moreover, by installing the baffle, the base shear slightly increases whereas overturning moment remarkably reduces.}, Keywords = {liquid storage tank,annular baffle,Boundary element method,sloshing,seismic analysis}, volume = {12}, Number = {2}, pages = {11-22}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-4987-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-4987-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {GhazanfariHashemi, S. Ghazanfari Hashemi1 and Etemad-Shahidi, A.}, title = {Prediction of Scour Depth Around Bridge Pier by Support Vector Machines}, abstract ={  Abstract:   Scouring is one of the main causes of failures of bridges and piles in rivers and marine environment. So the estimation of scour depth around bridge piers and piles is of great importance. On the other hand, since the scour depth properties should be considered in designs by the designers, the importance of acceptable accuracy to estimate the scour depth properties will be quite highlighted. Regarding the importance of scouring investigation, there are several empirical formulas that have been presented by researchers but acceptable results have not been provided yet. Considering the fact that the prediction of scour depth around a pile is complicated and is affected by sediment characteristics and sediment transport mechanism, current properties and pile geometries, new approaches other than empirical ones are being sought by researches. Recently alternative methods like data mining approaches have been widely applied to simulate complicated problems. Artificial Neural Networks (ANN) as a famous data mining approach has been successfully used to estimate the scour properties around a pile. However, performances of Support Vector Machines (SVM) as another type of data mining approach are not explored yet. SVM has been recently applied in fields of particle identification, face identification, text categorization and bioinformatics. In this study SVM is applied to estimate the scour depth around a pile and the results are compared with those of the ANN by MLP network with one hidden layer and back propagation training algorithm. Performances of all methods are tested by experimental data sets and the results are compared using statistical measures. Results of statistical measures of verification stage indicate that SVM provides a better estimation of scour depth than ANN and empirical formulae. They also indicate that data mining approaches provide better prediction than empirical approaches.}, Keywords = {ANN,Scour depth,Bridge pier,Pile,Data Mining}, volume = {12}, Number = {2}, pages = {23-36}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-5542-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-5542-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Gholampour, S. and Maalek, S.}, title = {An Experimental Study of the Influence of the Degree of Bolt Tightness on the Effective Length of Compression Members of Double Layer Space Structures Composed of Ball Joints}, abstract ={  Abstract:   A search of the published literature reveals that studies related to the effects of the degree of bolt tightness on the behavior of space structural joints and consequently on the member behavior and the overall response of space structures are rather limited. An experimental investigation of the effects of bolt tightness on the rigidity of double layer grids, carried out previously by the authors, had revealed the significance of the degree of bolt tightness on the overall rigidity of the tested structures. The present research is concerned with an investigation of the effects of the degree of bolt tightness on the end conditions and consequently on the effective lengths and the slenderness ratios of compression members of double layer space structures. An experimental program of work was conducted on more than 40 test specimens consisting of typical pyramidal modules of representative double layer grids to observe the influence of the degree of bolt tightness on the effective length and load carrying capacity of diagonal compression web members of such modules. Each module was fabricated by practically identical tubular members and the matching MERO type ball joints. However, different modular specimens were constructed using tubular members with different diameters and cross sectional properties. In each individual test specimen, it was attempted that the bolts connecting the members to the ball joints be tightened by the same applied torque to achieve an identical degree of tightness in all its joints. However, different values of applied torques were used to tighten different test specimens. Following the preparation of the test specimens tightened with different applied torques, a monotonically increasing concentrated load was applied at the upper node of each specimen. The tests were continued up to failure and in each test the displacement of the central top node just underneath the applied load was measured as the main component of the response of the test module. The observations indicate that the degree of bolt tightness has a significant influence on the effective lengths and consequently the load carrying capacity of compression members of such modules. However, over-tightening may cause failure of connection sleeves. Also, bolt pre-stressing shall not be made to a degree that causes brittle fracture of pre-stressed bolts or premature tearing of member to end cone welded connections under additional applied tension. On the basis of the observed behavior and supporting theoretical studies, the effects of the bolt tightness on the behavior of double layer space structures have been discussed in the context of design assisted by testing emphasized in Chapter 7 of the Iranian Code of Practice for Space Structures. With due consideration of different aspects of the influence of the degree of bolt tightness on the behavior of joints, members and modules, as well as the overall structural behavior, some practical recommendations have been presented to improve the reliability of structural performance through increasing rigidity and load carrying capacity of such double layer space grid structures, that can be achieved as a result of a proper choice of the bolt tightening procedure.}, Keywords = {}, volume = {12}, Number = {2}, pages = {37-50}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-2078-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2078-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {fathi, m. and daneshjoo, farhad and ghanbari, hamidrez}, title = {Seismic Behavior and Failure Mechanism of the Steel Moment Frames with Composite Beams}, abstract ={This paper examines the dynamic behavior of steel moment-resisting frames with steel-concrete composite beams with welded connections. One story-two bay frames with and without composite beams with rigid and simple connections were modeled with ABAQUS software and analyzed under earthquake accelerations. The distribution pattern of plastic hinges, rotation of plastic beam to column joints, plastic energy dissipation capacities of frame components and crack mechanism of slabs near the interior and exterior connections were studied. The results revealed that the frames with composite beams and welded rigid connections have the lowest values of period, plastic energy dissipation capacity, plastic rotation of joints and early frame mechanism. Failure mechanism in the exterior connection was in the form of concrete pre-tensioning from the starting at the corner of the column stretching in oblique around the edges of the slab. At the interior connections, it was in the form of concentrated compressive stress over the outer flange of the column. Strength and ductility of steel in tension and compression capacity of concrete in steel-concrete beams (composite beams) make this system suitable for long spans and considerable growth in recent years. In Euro Code 8 , rules are stated for mechanisms between concrete slab and steel column in bending and sagging moment modes. The mechanism in bending and sagging moment regions, where concrete slab has enclosed steel column, is shown in Figure 1. In the first mechanism, the compressive stress is applied directly onto the outer side flange of the column. Whereas in the second mechanism, the concrete slab exerts pressure through a 45 degree angle to the column web. The performance of the first mechanism leads to removal of contact friction between the concrete slab and the column. But the second mechanism leads to removal of contact element (Hard Contact) between the concrete slab and the inner core of the column web and flange. Therefore, activation of both mechanisms manifests a better performance of the system. Formation the plastic hinges in frames generally start at the column base, particularly at the middle column and then expand to other members, connections and the concrete slab. In this study, the use of composite beam, instead of steel beam, causes plastic hinges to form in the connections instead of beams. In composite frames with simple connections, due to stress concentration, the major plastic hinges are formed at the welded connections. In these frames, the first plastic hinge is formed earlier than others. But the failure capacity of these frames is higher than rigid ones. In rigid connections, the added rigidity due to enclosure by concrete slab causes initial stiffness for the frame and delays the formation of the first plastic hinge. However, it induces sudden stresses on the welds at the upper part of the beam. Thus will eventually lead to weld rupture and slab failure. This produces early failure in the frames.     On the basis of the observed behavior and supporting theoretical studies, the effects of the bolt tightness on the behavior of double layer space structures have been discussed in the context of design assisted by testing emphasized in Chapter 7 of the Iranian Code of Practice for Space Structures. With due consideration of different aspects of the influence of the degree of bolt tightness on the behavior of joints, members and modules, as well as the overall structural behavior, some practical recommendations have been presented to improve the reliability of structural performance through increasing rigidity and load carrying capacity of such double layer space grid structures, that can be achieved as a result of a proper choice of the bolt tightening procedure.}, Keywords = {Skeletal Space Structure,Double Layer Grid,MERO Type Jointing System,Degree of Bolt Tightness,Effective Length}, volume = {12}, Number = {2}, pages = {51-59}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-8506-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-8506-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Mamdoohi, Amir Reza and Mahpour, Alireza and Yousefikia, Mohamm}, title = {Minimum Spanning Tree concept development to the case of loaded networks and its application in transportation analysi}, abstract ={Minimum Spanning Tree (MST) is a mathematical programming problem that may be applied for analyzing transportation network structure and its performance, like its connectivity and link prioritization. Generally, the cost associated with each link is its Free Flow Travel Time (FFTT), however in this paper this concept is developed to the case of a loaded network with capacity constraints and its application to transportation network planning is examined for times of disaster, when the life of many people is involved. In this paper equilibrium travel time for a loaded network is proposed as the link cost and the problem is formulated and solved for Tehran province network. Results show that based on equilibrium travel times, the total cost of MST will have an 8 percent increase from 25973 to 28081 seconds and about 30 percent of the links in the new MST will change. It is also observed that if the MST based on FFTT is used for computing the total cost of the loaded network, the total cost will be 30232 seconds which demonstrates 17 percent increase in cost and 9 percent in error.}, Keywords = {network analyses,minimum spanning tree,Cost,travel time,Tehran city arterial road network}, volume = {12}, Number = {2}, pages = {61-69}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-10584-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-10584-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {sasani, moammad and Yazdani, Mahmou}, title = {Numerical simulation of frictional behavior of strike slip North Tabriz fault using finite element method}, abstract ={In this paper, the finite element code (ABAQUS) is used to present numerical modeling of strike-slip North Tabriz fault. To investigate the frictional behavior of fault the slip weakening law is assigned to the fault. This law is based on stick- slip instability mechanism. Fault modeling has been done in three-dimensional using ABAQUS software. The model involves a vertical strike-slip planar fault that resides in elastic crust. In this model only the upper solid part of With this analysis, verification of the constitutive relation of friction has been done. The second analysis crust is simulated and topography effects have been ignored. The fault is simulated as 2D vertical contact elements. The results have been verified with geological data such as rate of displacement on fault and verifications demonstrate satisfied convergence. For friction of fault, the results with two coefficient factors are compared with GPS data and coefficient factor of 0.1 showed better convergences.}, Keywords = {Finite Element,3d simulation of fault,stick-slip,North Tabriz fault}, volume = {12}, Number = {2}, pages = {71-83}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-2830-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2830-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Bakhtiyari, S. and KhaliliJahromi, K. and .M.Kari, B and Hedayati, M.J.}, title = {Research Note» Investigation on Physical, Mechanical and Reaction-to-Fire Properties of EPS Blocks in Block and Joist Floor System}, abstract ={One of the important applications of Expanded Polystyrene (EPS) in Iran is its use as infill block in Block and Joist Reinforced Concrete Floors. The properties and performance of EPS blocks in this floor system, including reaction-to-fire, mechanical properties, thermal resistance and acoustical performance of the system, was studied. Fire behavior of blocks was tested with ISO 5660 cone calorimeter test method. The fire properties of standard and flame retarded types of EPS were measured and discussed, including time to ignition, average and peak values of heat release rate and total heat release. The influence of type of EPS on its fire behavior was investigated. The results showed that the time-to-ignition and total heat release parameters can not be a characteristic value for distinction between standard and fire retarded types of EPS under cone calorimeter test condition. The reason is that both types are flammable and burn completely at fire temperatures. The peak value of heat release rate (PHRR) of EPS is the most important parameter that can be utilized for distinction of Standard and flame retarded types of EPS with cone calorimeter test method. PHRR values higher than 300 kW/m 2 were achieved for standard types, but the results for flame retarded ones were less than 250 (and mostly less than 200) kW/m     2 . The fire risks of specimens were also evaluated using Conecalc software and Richardson method. The results showed that even flame retarded   EPS needs to be protected with a thermal barrier in building applications. Moreover, it is required that the   protective barrier be mechanically fixed to the structural system, since EPS melts and recedes away heat,   once it is exposed to high temperatures. Hence, it is not able to keep barrier, say plaster, in its position.   The flexural strength of blocks under static and dynamic loads and its relation with density and   dimensions of blocks was evaluated. The results showed that minimum 12 and 14 (kg/m     3 ) density of foam is required respected for 25 and 20 cm of height of blocks with a width of 50 cm. An optimum 27      2 mm was obtained for the width of sitting section of blocks on joists. The influence of different properties and   geometry of EPS block (conductivity, width, height and existence of a thermal covering layer under joists)   on thermal resistance of floor system was also studied. The THERM software, Enery Efficiency and   Renewable Energy Program, was used for evaluation of thermal resistance of the floor. The increase of   height and width of blocks caused improvement in thermal resistance of the floor system, but the best result   was obtained when a thermal covering layer was considered under the joists. The acoustical results showed   that the replace of EPS blocks with hollow clay blocks does not influence importantly the impact sound   insulation of the floor system. Neither of them can fulfill the impact sound acoustical requirements and   need to be improved with an extra system, like a floating floor or an appropriate elastic floor covering for   this purpose.    }, Keywords = {Thermal insulation,Expanded polystyrene (EPS),Block and joist floor system,Fire safety,Impact sound}, volume = {12}, Number = {2}, pages = {85-95}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-8352-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-8352-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {davachi, amir mohamad and Zeynodini, mostaf}, title = {«Research Note» Seismic Response of a Multi-Span Pile and Deck Structure to Near and Far Field Horizontal Excitations}, abstract ={  Abstract:   During the past decades, there has been an ever increasing demand for construction of new wharves and port facilities in Iran. This is partly because of the recent rapid demographic, social and economic developments, increase in offshore oil and gas activities and also long coastlines available in the country. Wharves، Piers and jetties are lifeline structures, which provide a cost effective means for transporting large quantities of goods and raw materials into and out of a region. Harbor structures also play a central role in management of an abnormal condition such as an earthquake. For long structures such as wharves and jetties, transient ground deformations induced by seismic wave passage and effects from the spatial difference in ground motion become important. On the other hand, if a port facility is located close to the seismic source, it will become subject to the near field pulse type excitations. An analytical approach has been used to address the problem. Linear and non-linear response of simplified structural models to near-fault and far-fault strong ground motions is investigated. The model approximates a structure by an equivalent oscillator consisting of a rigid beam supported by several rigid mass-less columns. Bi-linear rotational springs connect the columns to the deck and the base of the structure. The system has been studied under two pulses type (fault-normal pulse and fault-parallel pulse) and 108 near field and far field earthquake excitations. In this study closed form solutions for the dynamic response of multi span pile and deck structures have been developed. Material non-linearity, large deformations and P   effects are taken into consideration. The central difference method is employed to solve the nonlinear equations of motion. The model is then used to analyse the structure under incident pulse type near-field excitations. Effects from strain-hardening, columns height, the seismic source distance, magnitude of the excitation, type of the excitation (pulse or random), have been investigated and compute the reduction factor and compare with the common design rules. In general it has been found that the classic design criteria for the strength reduction factors provide non-conservative results in a number of occasions.}, Keywords = {ductility,Strength reduction factor,Near Field Earthquake,Far Field Earthquake and Wharf}, volume = {12}, Number = {2}, pages = {101-111}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-7531-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7531-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {SivandiPour, Abbas}, title = {Determination of the natural frequency of the moment connections steel beams by artificial neural networks}, abstract ={Sensible vibration of steel beams in long spans is undesirable issue in the buildings. These beams may be vibrated during people passage, although the strength calculations of this beams to be performed, accurately and drift control index based on buildings codes to be considered. Iranian Steel Buildings Code has offered a formula for controlling of vibration of beams in building frames with pin connections in serviceability phase. However, this code has not presented criteria for beams include fixed connections. Since these beams have the considerable portion of building frames, their vibration control needs special attentions. The presented equations for determination of beams frequency are complicated and have been not used for control of buildings floor vibration. In this paper, the mentioned formula in forenamed codes has been discussed. The dynamic analysis, finite element method (FEM) and artificial neural networks (ANN) techniques have been adopted to constitute the frequency equations of the fix ends and cantilever steel beams. Comparison of resulted frequency from presented equations and ANN showed that the error is low. Furthermore, it is suggested that use proposed equations for determination of frequency of moment connection beams.}, Keywords = {Cantilever beam,Finite Elements,Artificial Neural Networks,Natural Frequency,fixed beam}, volume = {12}, Number = {2}, pages = {113-122}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-6609-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6609-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Khanzadi, m and Khazaeni, G. Khazaeni and Foshati, A.}, title = {Influence of High Initial Temperature Casting on Microstructure and Chloride Penetration in Concrete Containing Silica Fume}, abstract ={Abstract: The durability of concrete structures against corrosion due to high concentration of chloride ion is considered as a main concern in these kinds of structures in Persian Gulf area. However, increasing the initial temperature its effect on concrete microstructure can intensify this issue & severely increase the concrete corrosion rate. This article deals with the high initial temperature effect on chlorine ion penetration in concrete, particularly concretes consisted of silica fume. Evaluation of high initial temperature has been done by making samples in different temperature till initial setting & keeping in the same conditions in the environment temperature to simulate the environmental conditions of Persian Gulf. For this purpose, the changes of concrete micro structure due to initial temperature increase & its effect on concrete resistance properties against chloride ion penetration have been studied. In this paper, the influence of high initial temperature on chloride penetration and microstructure of concrete containing silica fume was investigated. Two different mixes at three different initial casting temperature (20-40°c) were studied: a control mix in which no cement replacement materials were added and a mix where cement was partially replaced 6% silica fume (by weight), at a constant water-to-binder ratio of 0.45 and a cement content of 400 kg/m3. High initial temperature casting was employed to simulate concrete temperature in Persian Gulf hot climate. The results show that chloride penetration at 40°c is directly related to increase in the porosity of the binder phase and the absorption of concrete. The Higher chloride penetration resistance was observed when cement is partially replaced with silica fume. From SEM result recognized silica fume particles make core sites to cement hydration, therefore make more consistency micro structure and decrease pore size distribution. It is concluded that increasing the initial temperature of the concrete in the time of casting & formation, leads to accelerating the hydration & therefore the heterogeneous distribution of products in the mixture. This phenomenon causes the bigger pores in the concrete structure by increasing the temperature and more space for chloride ion penetration. So, high casting and initial temperature leads to increasing chloride ion penetration & reduction of concrete resistance against corrosion. By adding silica fume to the mixture, size & the distribution of pores improve and the temperature increase effect on parameters of chloride penetration & corrosion decrease. Hence, the corrosion behavior (Chlorine ion penetration coefficient & electrical potential) of 40°c silica fume included specimen are improved than reference concrete.   Keywords: Initial Temperature, Corrosion, Chloride diffusion, Silica Fume}, Keywords = {corrosion,Chloride diffusion,Initial Temperature,Silica Fume}, volume = {12}, Number = {3}, pages = {1-10}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-6579-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6579-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Ayati, , B. and KhalilArya1, f and Ganjidoust, H}, title = {Comparison of Conventional and Packed-Cage RBC in Hydroquinone Removal}, abstract ={  Abstract: Hydroquinone is one of the most important phenolic compounds, which has a wide application in industries such as rubber, photo developing, cosmetic, and anti-oxidants. Because of its toxic effects, an efficient system should be provided for treating these kinds of wastewater. Therefore in this study, the performance of conventional and packed-cage RBC biological systems in treatment of wastewater containing hydroquinone, and parameters affecting the process were studied. In this study, the removal efficiency of hydroquinone was investigated in two different laboratory scale RBC systems. The first system was a two-stage RBC with rotating discs and the second one was a one-stage packed-cage RBC with bee-cell 2000 biofilm carriers. Each stage of the rotating discs RBC was consisted of 27 parallel plexiglas rotating disks with 15 cm in diameters. The packed-cage RBC had a net drum full of biofilm carriers with specific surface area about 650 m2/m3. Both systems had a total area of 2 m2 and were fed by a peristaltic pump. During the startup, the reactors with sludge seed, daily dosage of 200 mg/L COD as glucose and synthetic wastewater was fed to each reactor. After increasing biofilm mass, the acclimation was started with stepwise substitution of glucose with hydroquinone (CODhdroquinone/CODtotal was increased about 10% in each step). After acclimation stage, the amount of COD was being increased stepwise up to 5000 mg/L. Both RBC systems as advanced biological processes had proper COD removal efficiencies for treating hydoquinone synthetic wastewater. Up to the maximum 90, 93 and 88 percent removal efficiencies were obtained in RBCI, RBCII and packed-cage, respectively for COD concentration of 1000 mg/L, hydraulic loading rate of 1.5 L/m3.d and optimum rotation speed of 10 rpm. Also, During the experiments up to 4000 mg/L influent COD, RBC with rotating discs had higher removal efficiencies (about 5%-15%) but at higher loading rates, packed-cage RBC had better results. The effect of hydraulic loading, and the rotational speed of disks in the performance of the both systems were studied. The results proved that the amount of hydroquinone removal increased with raising the rotational speed of the disks up to 10 rpm, and increasing hydraulic loading had a negative effect on the COD removal efficiencies in both conventional and packed-cage RBCs. Also COD concentration increased up to 10000 mg/L in one step whille the hydraulic loading rate and rotational speed were 1.5 L/m2.d and 5 rpm, respectively. The results showed that conventional RBC had a better performance for the organic shock. For ensuring of hydroquinone biodegradation in the RBC systems carbon-13 NMR spectroscopy was also studied.}, Keywords = {RBC,Aromatic,hydroquinone,packed-cage}, volume = {12}, Number = {3}, pages = {11-19}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-7845-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7845-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {DavoudiKia, A. and Shahbeyk, S.}, title = {The Effect of Cellular Structure on the Yield Surface of 2D Metal Foams}, abstract ={Metal foams are a new class of materials with interesting structural properties; however no comprehensive understanding of their inelastic behavior has been established yet. Since the experimental studies of these materials have their own limitations, there is a growing research interest towards the mesostructural modeling of these materials. Accordingly many researchers have been trying to generate realistic and representative numerical models of the foams and prepare computational labs in which different aspects of foams mechanical behavior can be thoroughly investigated. The following three kinds of mesostructures have been commonly employed: (1) models based on a unit cell or a building block, (2) random Voronoi diagrams, and (3) CAD structures provided by the X-ray micro-computed tomography. In the current study, the physically representative circle set Voronoi diagrams are employed to define the geometry of 2D metallic foams. It is assumed that the minimum and maximum radii of the circular generators are 0.5 and 1.5 mm, respectively. The first sample is generated using linear distribution of cell size while, compared to the first sample, the second and third specimens have less and more small cells. An extra specimen (the forth sample) is also created with the same structure of the first one unless its edges are straight. In the next step, the FE models of the specimens are created using second order Timoshenko beam elements. Finally, the effects of microstructural features (e.g. strut curvature and cell size distribution) on the initial yield surface, elastic properties, and failure modes of the foams are numerically investigated under various biaxial loading conditions. Displacement-controlled loading is used. A newly energy-based approach developed for the identification of initial yield points has been incorporated. The results show that: (a) the size of the initial yield surface is significantly influenced by the curvature of the cell struts, (b) in the principal stresses space, the initial yield surface is bigger in the tension-tension region, (c) for a constant relative density, the presence of more big cells in a sample increases the size of the yield envelope, and (d) the macroscopic yield properties of the specimens can be interpreted according the microscopic failure mechanisms of the plastic yielding, elasto-plastic buckling, and plastic hinging of the struts. Furthermore, it is found that the previously proposed energy-based method for the identification of yield initiation under multiaxial loading conditions has serious shortcomings and needs revision.}, Keywords = {Finite Element Analysis,Microstructure,Yield Surface,metal foam,Voronoi Diagram}, volume = {12}, Number = {3}, pages = {31-33}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-1941-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1941-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {RakhshaniMehr, M. and Esfahani, M.R. and Mousavi, S.R.}, title = {Bond Strength between Concrete and FRP Bars for Lap-Spliced Concrete Beams}, abstract ={Steel is considered to be one of the desirable materials used for reinforcing concrete structural members. However, the corrosion of steel bars has been always a threat for the service life of reinforced concrete members in corrosive environments. Fiber Reinforced Polymer (FRP) bars can be used as reinforcing materials due to their corrosion resistance. FRP reinforcing bars are available in different grades of tensile strength and modulus of elasticity. These bars have high tensile strength and durability and display linear elastic behavior up to their failure. The behavior of concrete beams reinforced with FRP bars is different from that of steel reinforced concrete beams. Concrete beams reinforced with glass fiber reinforced polymer (GFRP) bars exhibit large deflections and crack widths as compared with steel reinforced concrete beams due to the low modulus of elasticity of GFRP. In addition, the bond between concrete and FRP bars is different from steel bars because of the difference in their surface geometries and mechanical characteristics. This paper proposes an equation for the bond strength of lap-spliced concrete beams reinforced with FRP bars. First, equations for displacement modulus and local bond strength of FRP bars are formulated by pullout test results, tested by other researchers. Then, using the local bond strength equation and based on the experimental results of lap-spliced FRP reinforced concrete beams, an equation for bond strength of splices is derived. In the formulation of this equation, the non-uniform distribution of the bond stress along the splice length is considered. The effects of concrete cover and transverse reinforcement are also taken into account in the proposed equation. Transverse reinforcement has an important role in the bond strength of beams with spliced bars. Transverse reinforcement confines developed and spliced bars by limiting the progression of splitting cracks and increases the uniformity of bond stress distribution along the splice length and thus, increasing the bond strength. The bond strengths calculated by the proposed equation are compared with the experimental values. The comparison shows that the proposed equation predicts the splice strength accurately. Also, calculated bond strengths are compared with the values predicted by different code provisions and other models. The average and standard deviation of the experimental over calculated bond strength ratios obtained by the proposed equation are 1.00 and 0.14, respectively. These ratios are 0.65 and 0.19 for the ACI440.1R-06 code, 0.55 and 0.15 for the CAN/CSA-S6-00, 0.67 and 0.16 for the CAN/CSA S806-02 code and 0.99 and 0.36 for the Aly equation. Compared to Aly equation and design guidelines, the proposed equation for calculating the bond strength shows better agreement with experimental values. In addition, code equations overestimate the bond strength of GFRP bars in splices of beams.}, Keywords = {FRP bars,transverse reinforcement,reinforced concrete beam,bond strength,splice}, volume = {12}, Number = {3}, pages = {33-45}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-11275-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11275-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Ramezani, S. and Bahar, O.}, title = {Identification of Natural Frequencies Based on a New Enhanced Hilbert-Huang Transform}, abstract ={Hilbert-Huang transform (HHT) consists of two main parts: (1) empirical mode decomposition (EMD) to extract intrinsic mode functions (IMFs) and (2) Hilbert spectral analysis to obtain time-frequency characteristics of the IMFs through the Hilbert transform. Recently, a new enhanced HHT is proposed by the authors in which, two mathematical limitations that restrict the application of the Hilbert transform are circumvented and also an additional smoothing parameter is applied to decrease noise effects on the results. In this paper based on the HHT approach, a simple method for output-only identification of natural frequencies of linear structures is proposed in which HHT or enhanced HHT can be employed. In the proposed method, ambient response data measured at all degrees of freedom of the structure are used to obtain an averaged marginal spectrum. The averaged marginal spectrum is used for identifying the natural frequencies of the structure. In order to validate the effectiveness of the proposed identification method, ambient response data of an arch bridge and a 15-story building are examined. In the first case, the first six natural frequencies of the bridge in vertical direction are extracted. And in the second case, the first three natural frequencies of the building in East-West, North-South and torsional directions are identified. From the results, first, it is found that the enhanced HHT by employing the smoothing parameter is more efficient than the HHT in increasing the readability of the time-frequency-amplitude spectrum and also is capable to provide more accurate amplitude-frequency distribution; second, by comparing results of the proposed method with those obtained from other valid methods, it is concluded that the proposed identification method by using the enhanced HHT is accurately able to estimate the natural frequencies of structures. Regarding to simplicity of the proposed method, it can be applied as an efficient tool for identification of structures or employed to extract changes in frequencies due to occurrences of damages during strong ground motions.}, Keywords = {Signal processing,Enhanced Hilbert-Huang transform,Structural system identification,Identification of natural frequencies}, volume = {12}, Number = {3}, pages = {47-59}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-1043-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-1043-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Amouzadeh, M. and SoltaniMohammadi, M. and Tasnimi, A. A.}, title = {Behavioral Curve of Unreinforced Masonry Walls Confined by RC Ties}, abstract ={Confined masonry consists of load-bearing walls with some slender cast-in-place tie columns connected with tie beams. These confining elements are usually made of reinforced concrete and especially located around the critical points such as openings and corners. Although the response of confined masonry walls has been extensively studied in experimental tests worldwide, the analytical models capable of capturing deformation and strength characteristics of these walls and also technical guidelines which can help engineers to numerically evaluate the seismic resistance of confined masonry structures are rate. In this study, the micro-modeling strategy is adopted for the numerical simulation of unreinforced masonry walls confined by reinforced concrete tie columns and beams. A modified version of general path dependent contact density model is used to simulate the complicated response of brick-mortar interaction in the mixed mode of shear and axial deformations. A nonlinear finite element analysis program called “WCOMD_SJ” is used for this purpose. This program has been developed at University of Tokyo and is an analytical tool for two-dimensional static and dynamic nonlinear analysis of reinforced concrete structures based on fixed smeared crack approach. This program has been modified by the second author for nonlinear macro and micro analysis of masonry structures. In order to validate the analytical approach, experimental test results and gathered data from literature are used. The comparison between experimental and analytical results shows good agreement between analytical and experimental findings. Then through a parametric study, the effect of opening and also the interactional effect of adjacent walls on the lateral response and strength of confined masonry walls are numerically investigated. Finally a simple but rational method for modeling the nonlinear behavior of confined masonry walls is proposed. The comparison between this model and numerical results confirms the reliability of the proposed model. Since available experimental results are rare, an analytical study is also performed for investigating the accuracy of the proposed relations.}, Keywords = {Seismic behavior,confined masonry,micro modeling}, volume = {12}, Number = {3}, pages = {61-75}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-3235-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-3235-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Maleki, M. and Bayat, M. and Mirzaee, A.}, title = {Effects of Matric Suction on Mechanical Behavior of Clayey Silty Sandat Low Effective Confining Stress}, abstract ={There is a very few experimental data on the mechanical behavior of unsaturated sand-fine mixture, particularly in constant water content conditions, because of the technical difficulties and time-consuming nature of measuring suction and deformation. This paper presents the results of a series of constant water constant triaxial tests on the specimens of an unsaturatedclayey silty sand in low confining pressure.The effective confining pressures selected in this study are 25, 50 and 100kPa. In comparison with the majority of experimental works, existing in the literature, these levelsof confining pressures are relatively low and this aspect is fewer focused.The effect of matric suction on stress-strain behavior of selected soil in different density and confining pressure is the main aim of the present study. The tests were carried out as Constant water content (CW test). This type of test represents field un-drained condition, where, the rate of loading is much quicker than the rate at which the pore water is able to drain out of the soil. Axis translation technique and double-walled triaxial cell have been used to measure the soil matric suction and variation of pore air volume respectively. Test specimens were prepared at two different compaction conditions prior to testing to achieve different initial density. According to the obtained results, it is found that the mechanical behavior of soil mainly depends on the initial density, the mean net stress and the initial matric suction. Also the volume and pore water pressure changes are totally different in specimens with different initial condition. However, the results of tests indicated that the shearing strength of sand-fine mixture increase non-linearly with matric suction.The results of tests show that the soil shear strength is increased with increasing in both effective confining and matric suction. However the effect of confining pressure is more significant than matric suction. The matric suction and confining pressure play an important role on volume changes of unsaturated soil, however the effect of confining pressure is more considerable. For all of the tests, the specimens were subjected to large axial strain. This allowed us to calculate the deviatoric and mean net stresses at critical state. The comparison of results in q: p-uacoordinate, indicate that, the position of critical state lines for unsaturated soil changes as a function of matric suction. However, these lines can be considered as parallel to each other.Deviatoric stress (q) intercept of critical state line increases with increasing matric suction. Besides, initial density for unsaturated specimens influences the shear resistance corresponding to large strains. However the tests results on saturated specimens, according to the classical critical state soil mechanics, indicated that, soil resistance at critical state is not a function of soil density.}, Keywords = {Shear Strength,Matric suction,Unsaturatedsoil,Density,Confining stress}, volume = {12}, Number = {3}, pages = {77-89}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-6497-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-6497-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Esmaeeli, M. and Ghahari, S.A.}, title = {Laboratory Study on the Effect of Poly-Propylene Fiber Reinforced Concrete for Application in Sleeper}, abstract ={Concrete sleeper as an important component of super-structure has a remarkable role in proper performance of ballasted track. Nowadays, railroads companies of the world are willing to increase strength of concrete sleepers and use new solutions for repairing and rehabilitation of these elements with low cost. Sleeper damage is usually occurred in forms of cracks that have appeared by repetitive loadings and thermal effects. Corrosion of reinforcement tendons in some special regions is another problem that causes serious damage in sleeper. Since these concrete elements are being exposed to various weather conditions, enhancing their resistance against corrosion and improving their durability has a great importance as well. there are many ways to improve concrete characteristics like using FRP by covering concrete in regions that have high stress, but this solution will not increase corrosion resistance.Using epoxy resins that can be sprayed as nano material on concrete is another way to reduce permeability, but it is an expensive way. One of the useful and cost benefit ways to increase the corrosion resistance and reduce the cracks extension is using Poly-Propylene fibers in mixture of concrete. Many researchers have been studied on using Poly-Propylene fibers in mixture of concrete and shotcrete.these reasearches are presented below : reaseraches  have been accomplished on using Poly-Propylene fibers in shotcrete.the results have shown that rebounding of shotcrete has been being decreased 30% volume of cement, and cracks have been being decreased about 20% .In case of fiber reinforced concrete also reasearches  have been accomplished the result of  test on a concrete cube; the compression strength of specimens till 28 days ,  decreases but it increases till the day 90.As mentioned, many researches have been accomplished on using Poly-Propylene fibers in mixture of concrete and shotcrete. Moreover the Poly-Propylene fibers can control the propagation and extension of the surface cracks. Regarding SEM results, this increase is due to enlargement of Poly-Propylene fibers that can fill micro cracks, and of course the bonding of the concrete structure will be enhanced. Considering the significant effect of Poly-Propylene fibers on concrete behavior, the current research is devoted to investigating the influence of Poly-Propylene fibers on improving the electrical resistance, tensile and flexural strengths of the concrete in sleeper. In this matter an optimal value of 0.7 kg/m3 of Poly-Propylene fibers was achieved during the laboratory tests on fresh and hardened concrete, including 72 laboratory specimens.}, Keywords = {-------}, volume = {12}, Number = {3}, pages = {91-101}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-11253-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11253-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Bagheri, A.R. and Zanganeh, H.}, title = {Comparison of the RCMT Test for Rapid Evaluation of Concrete Chloride Permeability With the RCPT and Electrical Resistance Test Methods}, abstract ={Abstract: Chloride penetration resistance of concrete is considered a key parameter affecting durability of structures exposed to marine environments. Chloride diffusivity of concrete can be determined by immersion or ponding tests. However such tests are time consuming and costly. These facts have lead researches to develop accelerated tests such as the rapid chloride penetration test RCPT (ASTM C1202). In the RCPT test, the electrical charge passing during six hours through a 50 mm concrete disc, under potential difference of 60 volts is measured. A main concern expressed for the RCPT test has been the rise in temperature of concrete specimens which results in a reduction in concrete resistivity. The other criticism towards the RCPT test is the role of ions other than chloride ion, particularly the (OH)- ion in conductance of electrical charge. It has therefore been suggested that some complementary cementitous materials can cause a reduction in the electrical charge passed, by reducing the concentration of (OH)- ions in pore solution. Another quick method for measuring chloride resistance of concrete is the Rapid Chloride Migration test RCMT (AASHTO TP64). This test is in general similar to the RCPT method. However for avoiding the heating of specimen, the applied voltage is adjusted in accordance with the initially passed charge. Also in the RCMT test, for avoiding the influence of other charge carrying ions, the actual chloride ion penetration into the specimen is determined. A further method proposed for appraisal of chloride resistance of concrete, is determination of electrical resistance. For avoidance of heating of concrete specimens, electrical conductivity measurements are carried out for short durations. This research was carried out with the aim of comparing the results of various quick methods for determination of chloride resistance of concretes containing various supplementary cementitous materials. In the experimental study the control mix had a water cement ratio of 0.38 and cement content of 420 Kg/m3. Mixes containing various amounts of supplementary cementitous materials including silica fume, fine fly ash, pumice, fly ash and slag were studied. For the RCPT test, the temperature effect resulted in considerable overestimation in the effect of using of supplementary cementitous materials in improving chloride resistance of concrete. Temperature rise did not occur during the RCMT test, and this test therefore does not suffer  In the case of optimum fiber value, the obtained results from laboratory tests have shown a reduction in compressive strength and value of ultrasonic test around 8.7% and 2.5% respectively. Moreover it has shown an increase in tensile strength, flexural strength, electrical resistance and value of VB test about 33%, 10%,11% and 51% respectively. Consequently utilizing such fibers in sleeper concrete could be suggested for practical applications.}, Keywords = {RCPT,Electrical Resistance,Poly-Propylene fibers,Concrete Sleeper,Tensile strength and Flexural strength,Compression strength}, volume = {12}, Number = {3}, pages = {103-112}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-11290-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11290-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Abdollahzadeh, Gh.R. Abdollahzadeh and Javidi, A.}, title = {Evaluation of Damage Distribution on Dual Smrfs with Concrete Shear Wall}, abstract ={In recent years, many large ground motions occurred very close to modern cities and caused severe damage to buildings. Damage to modern engineering structures is beyond engineers’ expectation, because the structures are thought to have been designed according to proper ground motion-resistant design standards. In these buildings, although the distribution of strength for all stories of designed structures was considered uniform, but the distribution of overall damage of stories was non-uniform and considerable damage for some stories was observed. In this study, 8, 12 and 15-story dual steel moment-resisting frames with concrete shear wall were designed as a residential building that was located in seismic zone 4 (very high relative seismic risk region). These structures were designed with uniform strength ratio for all elements according to the modal response spectra analysis and static equivalent lateral seismic load pattern that were typically recommended by most building codes. Then six severe ground motions recorded in soil type III with magnitude greater than 6.2 on the Richter scale, without forward directivity, were selected. Finally, all structures subjected to these six severe ground motions and distribution of damage was examined by using nonlinear dynamic analysis. According to the results, despite uniform distribution of strength for all elements, element types and stories in each structure, the distribution of overall damage for element types (e.g. beams, columns and shear wall) and stories and the distribution of local damage for elements are non-uniform and among different stories, first and last stories have minimum overall damage and among different elements types, the damage of the beams is more than columns and shear wall and increasing the number of stories has not been effected on the distribution of damage of elements, and for 8, 12 and 15-story distribution of damage of elements is similar. Evaluation of distribution of damage on elements illustrate that the beams and columns near the shear wall have been damaged more than the beams and columns that are located far from the shear wall. On some stories, the beams and columns near the shear wall have been damaged considerably, but the beams and columns that are located far from the shear wall have been remained elastic. Also, these results conclude that the distribution of overall damage on stories and element types are not adequate for evaluation of seismic damage and the local damage of each element should be examined separately, because from distortion of the results caused by the temperature effect. As the complexity of equipment and speed of testing for the RCPT and RCMT tests are similar, the RCMT test can be recommended for more realistic appraisal of concrete. There was good correlation between the results of the RCMT and electrical resistance test which shows a good potential for utilization of the electrical resistivity methods for appraisal of chloride resistivity of concrete.}, Keywords = {durability,RCPT,RCMT,Electrical Resistance,Supplementary cementitous materials}, volume = {12}, Number = {3}, pages = {113-124}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-10539-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-10539-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {AhmadiMousaAbad, N. and Moussavi, Gh.R}, title = {The Removal of Sodium Dodecyl Sulphate Anionic Surfactant from Wastewater Using UV/H2O2 Advanced Oxidation Process}, abstract ={Surfactants are used to aid in cleaning equipment and surfaces by restaurants, dairy farms, and food processing plants and are among the basic constituents of organic pollutants in domestic as well as industrial wastewaters causing great environmental damages. Due to their high volume use, surfactant chemicals have the potential for broadscale release into aquatic and terrestrial environment. Surfactants can reach humans, animals and plants from the ground waters used as drinking water supplies. Besides the toxic effects of surfactants their existence in waters even under the toxic level causes many adverse effects on biological life. They cause pathological, physiological and biochemical effects on aquatic animals. A large number of surfactants, including the anionic types employed in the present study, have relatively low biodegradability. Due primarily to economic reasons, it is impractical to replace those low biodegradable surfactants in all household and industrial applications. In the past decades, ozonation and other advanced chemical oxidation has been suggested and investigated by many researchers for pretreatment of refractory surfactants. These investigators have found that the biodegradability of the refractory surfactants can be considerably enhanced by ozonation or photocatalytic treatment. Although effective in improving the biodegradability of refractory surfactants, strong oxidation by ozonation or photocatalytic treatment is a relatively costly method. An alternative advanced oxidation method which is as efficient and yet less expensive to implement would be highly desirable. A method meeting these requirements and deserving attention is the UV/H2O2 oxidation process. This method employs hydrogen peroxide (H2O2) and UV to form a strong oxidizing agent (hydroxyl radicals) during the oxidation process. Hydroxyl radicals have been known to possess a stronger oxidation potential than ozone, 2.8 V for OH and 2.07 V for ozone. This study carried out at a bench scale unit consisted of a batch  UV reactor with a working volume of 80 ml to evaluate efficiency of UV/H2O2 AOP in the degradation of surfactant from synthetic wastewater.The effects of various parameters including reaction time, H2O2concentration was investigated. The concentration of model surfactant was determined by the acridin orange method.The present study showed that the UV/H2O2 AOP have higher efficiency than singl UV and H2O2 processes for sodium dodecyl sulphate( SDS) anionic surfactant removal. In this process for the solution with a surfactant concentration of 700mg/L and H2O2 conentration of 0.5mMol, the removal efficiency of 92% was achieved with a reaction time of 30 minute. Also the degradation efficiency was found to be decreased by releasing in surfactant concentration. UV/H2O2 advanced oxidation process is capable of degrading the SDS surfactant from wastewater by high efficiency.}, Keywords = {}, volume = {12}, Number = {4}, pages = {1-10}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-7409-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-7409-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Parsaeian, S.M. Parsaeian and HosseiniHashemi, , B. and SarvghadMoghadam, A.R}, title = {Inelastic Displacement Ratios for Structures on Firm Soil Sites Subjected to Iran Earthquakes Records}, abstract ={In this paper, results of  inelastic displacement ratios based on earthquake ground motions of Iran are presented. These ratios are calculated for single degree of freedom systems with elastic perfectly plastic behavior model and various strength reduction factors subjected to 204 earthquake ground motion records. These records are recorded on firm soil sites of Iran and have following characteristics 1) Recorded in earthquakes with seismic moment magnitude larger than 5,  2) At least one of the two horizontal components of records has peak ground acceleration larger than 50 cm/s2, 3) Recorded in free field stations so that potential soil-structure interaction effects omitted,  4) Records with hypo central distance larger than 15 km so that near fault effects omitted,  5) Recorded on soil conditions 1, 2 and 3 according to spectral ratio H/V of ground motions,  6) Records in which band pass range in correction process were at least between 0.33 to 20 Hz.  204 acceleration time histories including 70, 30 and 104 acceleration time histories related to soil condition 1, 2 and 3 respectively are used. In this statistical study, 422688 inelastic displacement ratios (related to 204 acceleration time histories, 296 period of vibration and 7 strength reduction factors) from response of SDOF systems with elastic perfectly plastic behavior model are calculated. Mean values of inelastic displacement ratios for each period of vibration and each strength reduction factor subjected to all 204 earthquake records and their dispersions are presented. The influence of period of vibration, strength reduction factor, soil condition, earthquake magnitude and hypocentral distance on inelastic displacement ratios are evaluated. This ratio in short period of vibration is larger than unit (maximum inelastic displacement larger than maximum elastic displacement) and for long period of vibration is close to unit (maximum inelastic displacement nearly equal to maximum elastic displacement). Soil condition effects on inelastic displacement ratio, for period of vibration larger than 1.5 second is very small and neglectable but neglecting of soil condition in periods between 0.4 and 1.5 second cause error up to 20 percent and for periods smaller than 0.4 second cause error up to 40 percent in estimation of inelastic displacement ratio. Neglecting of distance effects to focal of earthquakes in estimation of inelastic displacement ratio, for period of vibration smaller than 1 second, causes error up to maximum 20 percent. This error increase when strength reduction factor increases. For period of vibration larger than 1 second, neglecting of distance effect doesn’t make considerable error. Neglecting of magnitude effects of earthquakes in estimation of inelastic displacement ratio, for period of vibration smaller than 1 second, causes error up to maximum 60 percent. This error increase when strength reduction factor increases. For period of vibration larger than 1 second, neglecting of distance effect doesn’t make considerable error. By using of nonlinear regression analysis, a simplified equation based on mean results is calculated and Maximum inelastic displacement of single degree of freedom systems on Iran firm sites could be estimated using proposed equation and maximum elastic displacement demand. Finally, proposed equation is compared with C1 coefficient of target displacement in FEMA440.}, Keywords = {single degree of freedom,inelastic and elastic displacement,elastic perfectly plastic behavior model}, volume = {12}, Number = {4}, pages = {11-25}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-10572-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-10572-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Azar, A. and Saffarzadeh, M. and Ehsani, A.}, title = {Designing Mathematical Routing Model of Hazardous Materials Transportation (Case Study: the Fars Province Road Network)}, abstract ={In most cases, the place of producing and using hazardous materials is not the same and such materials should be transported from the production line to the consumption place. Because of the dangerous nature of such materials, safety indicators and criteria should be considered. More than 90% of hazardous materials transportation in Iran is by road. This shows the importance of attention to the safety factors. Although transportation departments or local governments are responsible for allocating acceptable paths that reduce risk, transportation companies usually look for some paths with lower travel times and fuel consumption. So many methods have been presented for designing the paths of hazardous materials transportation based on the trade -off between costs and risks of the transportation. Almost in all of them the national hazardous materials transport routing has been a decision for the matter in two levels, the government allocates a subset of the transport network to hazardous materials and the transportation corporations, choose their paths from this subset. However, the issue of justice in the distribution of risk is highly regarded in the states because feeling Injustice in received level of risk, might lead to public opposition to the routing of hazardous materials. Therefore in this research some routing models have been proposed. In the first mathematical model, we just consider the safety of paths and two major goals would be pursued. First we seek ways of minimizing risk in the whole studied path networks, and then this matter would be considered that the risk does not increase in each link more than certain amount, and in fact justice in the distribution of risk be established. This model was bi-level linear and transformed into a single-level mixed integer linear program by replacing the second level by its Karush–Kuhn–Tucker conditions and by linearizing the complementary constraints. Then we solve the MIP problem with a commercial optimization solver In the second model, in addition to the safety, the economic efficiency of the routes is considered. In fact, in this model, the results of the safety model will be used in a mathematical model with economic-safety approach. The real case study then has been used to evaluate mathematical In most cases, the place of producing and using hazardous materials is not the same and such materials should be transported from the production line to the consumption place. Because of the dangerous nature of such materials, safety indicators and criteria should be considered. More than 90% of hazardous materials transportation in Iran is by road. This shows the importance of attention to the safety factors. Although transportation departments or local governments are responsible for allocating acceptable paths that reduce risk, transportation companies usually look for some paths with lower travel times and fuel consumption. So many methods have been presented for designing the paths of hazardous materials transportation based on the trade -off between costs and risks of the transportation. Almost in all of them the national hazardous materials transport routing has been a decision for the matter in two levels, the government allocates a subset of the transport network to hazardous materials and the transportation corporations, choose their paths from this subset. However, the issue of justice in the distribution of risk is highly regarded in the states because feeling Injustice in received level of risk, might lead to public opposition to the routing of hazardous materials. Therefore in this research some routing models have been proposed. In the first mathematical model, we just consider the safety of paths and two major goals would be pursued. First we seek ways of minimizing risk in the whole studied path networks, and then this matter would be considered that the risk does not increase in each link more than certain amount, and in fact justice in the distribution of risk be established. This model was bi-level linear and transformed into a single-level mixed integer linear program by replacing the second level by its Karush–Kuhn–Tucker conditions and by linearizing the complementary constraints. Then we solve the MIP problem with a commercial optimization solver In the second model, in addition to the safety, the economic efficiency of the routes is considered. In fact, in this model, the results of the safety model will be used in a mathematical model with economic-safety approach. The real case study then has been used to evaluate mathematical}, Keywords = {Transportation,Hazardous materials,Faws province,Routing model}, volume = {12}, Number = {4}, pages = {27-35}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-300-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-300-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Olyaei, M. and Yasrebi, S.Sh. and Emami, M.}, title = {Seismic Behavior of Soldier Pile Support Systems for Deep Excavations in Coarse Grain Alluvium}, abstract ={Soldier pile consists of the passive reinforcement (i.e., no post-tensioning) of existing ground by installing closely spaced steel bars (i.e., nails), which are subsequently encased in grout and transfer the loads from steel piles to soil. As construction proceeds from the top to bottom, concrete is also applied on the excavation face to provide continuity. Soldier pile is typically used to stabilize excavations adjustment to the buildings to prevent surface movement and cracks in the buildings where top-to-bottom construction is advantageous compared to other retaining wall systems. For certain conditions, soldier pile offers a viable alternative from the viewpoint of technical feasibility, construction costs, and construction duration when compared to ground anchor walls, which is another popular top-to bottom retaining system. This paper addresses soil nails that are installed with a near horizontal orientation and are primarily subjected to tensile stresses together steel piles which act as cantilever beam with horizontal nails as supports. Soldier pile can be used for both temporary and permanent structures based on its service life or intended duration of use. Soldier pile is a form of ground retention used when ground conditions comprise of dense to moderately dense soils such as coarse grain alluviums. Soldier pile systems with lateral nails are used in many excavation projects. This method is one of the appropriate support systems in deep excavations. However, most of the researches have been focused on the effects of wall height on the stability of excavations in static conditions, but with increasing of the use of soldier pile systems in seismic regions, the dynamic stability of these structures cannot be ignored. According to increasing of the usage of the soldier pile systems in seismic active zones, it’s important to study the dynamic behavior of these structures. Hence, in this paper, the seismic behavior of soldier pile systems in Tehran coarse grain alluvium has been investigated. The methodology is based on pseudo-static approach to equalize the dynamic analysis. The numerical modelings have been done according to Finite Difference Method (FDM) to this equalization. Based on slope stability theory, it has been shown that the pseudo-static method is a suitable and simple approach to equalize dynamic behavior. Therefore, in this paper, a similar approach has been used to equalize dynamic behavior of soldier pile systems with considering a proposed pseudo-static coefficient. The failure surfaces in dynamic and pseudo-static  models efficiency. Network of this case study is the roads network of Fars province that it has 59 nodes and 80 arcs. Two groups of hazardous materials are considered and the risk factor is calculated for each group in all links. Each node can be the potential point of the demand or a point of supply. All paths can be used in both directions, and it has been assumed that the risk of passing hazardous material through the path between two nodes is equal for both directions. Risk index includes three factors, “population under effect”, “the environment assets”, and “the number and importance of road facilities across a link”. Results showed the best possible and the safest and most economical routes, would be obtained by solving the safety model and using the result of this model in the safety-economic model.}, Keywords = {Hazardous materials,Faws province,Routing model,Transportation}, volume = {12}, Number = {4}, pages = {37-49}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-4540-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-4540-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Ghanbari, A. and Davoodi, M. and NasrollahtabarAhangar, M.}, title = {Development of Pseudo-Static Method for Stability Analyses of Embankment Dams with egard to Foundation Effect (Case study: Masjed Soleiman Dam)}, abstract ={Pseudo-static method is one of the oldest and simplest techniques for seismic stability analysis of embankment dams. Selection of appropriate seismic coefficients is the foremost part of analysis in Pseudo-static method. Previous researchers and design manuals often suggest constant values for selecting the seismic coefficient, regardless of geometry and stiffness of foundation and the dynamic characteristics of the structures. In the proposed method, the seismic coefficient is a function of parameters α and β. Parameter β is indicative of acceleration amplification in the direction of the dam height, and is related to the geometrical specifications and material properties of the dam body and foundation. Therefore, β can be obtained through dynamic analysis. In this research, in order to obtain the effect of foundation on this parameter, a geometrical model of the Masjed Soleiman Dam has been analyzed dynamically using seismographs of earthquakes that occurred in different sites. Dam consultants used this value for the MDE of the Masjed Soleiman Dam site. Parameter was obtained by assessing the way in which the maximum acceleration varied at different points on the height of the dam. Also, the effect of far and near field records of earthquake are evaluated. In this research, the safety factor in a wedge corresponding to the seismograph that causes the allowable displacement in that wedge is assumed to be equal to one. Thus, available seismographs were scaled to peak acceleration values and, using them, the wedge displacement values were calculated. The safety factor changes were then calculated using the seismograph that caused the allowable displacement in the wedge. These safety factors were assumed to be equal to one, and the dynamic safety factor for each wedge was determined by comparison of the results obtained from the original seismograph. After comparison of the dynamic and pseudo-static safety factors, the desired safety factor was determined. The distribution of the horizontal acceleration corresponding to the safety factor was compared with the linear distribution of horizontal acceleration proposed in this article and the values of β were determined. Finally, a new technique to estimate the pseudo-static seismic coefficient is presented. Different conditions for foundation are assumed and results of analyses are evaluated. Results of this research imply that geometry, stiffness and   analyses have been compared and based on the comparison of axial forces in the nails (as the most important factor of the stability), the equivalent horizontal acceleration coefficient for the model is proposed. The applied forces cause the reinforcement tension and the mobilized tension force can overcome the soil tension weakness. Thus, predicting mobilized forces in soldier pile nails during earthquake is very important. The effects of most important parameters such as wall height, nail arrangements and soil types through numerical modeling of the soldier piles under dynamic loading by using FLAC have been investigated.}, Keywords = {Dynamic Analysis,soldier pile system,pseudo-static analysis,equivalent horizontal acceleration coefficient,Tehran coarse grain alluvium}, volume = {12}, Number = {4}, pages = {51-61}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-9856-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-9856-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Rahgozar, M.A.}, title = {Estimation of Overstrength Factor for Steel Plate Shear Wall Structures}, abstract ={Steel plate shear walls are very effective lateral load resisting systems with high lateral stiffness and ductility capacity. Although there are valuable experimental data available for such systems, most of the current seismic codes (including Iran’s Std. 2800) provide none or limited design provisions for such structural systems. One of the important seismic performance parameters of the structures is “over-strength factor” which is implicitly or explicitly part of seismic design base shear formulation. Most of the available data on this factor are obtained from experimental research and therefore results are limited to low-rise structures and/or with reduced scaled structures. The main objective in this research is to assess the over-strength factor for the steel shear walls. A closed-form-solution is proposed for obtaining this factor based on plate-frame interaction. It was found that the over-strength factors obtained by this method are in line with available experimental data and analytical results obtained in this study. In derivation of this closed form solution the following assumptions are made: 1) beam-to-column connection is rigid, 2) SPSW behaviour is affected by the interaction of the steel plate and its surrounding frame members, 3) the first storey, usually the soft storey, controls ductility and strength of the structure in general, 4) the beam remains rigid and the plastic hinges only form in the columns, 5) stresses due to the bending action in the plate do not interfere with the stresses due to buckling in the plate, 6) stress-strain relationship of the steel plate and the steel frame members are elastic-perfectly plastic. The experiments on SPSWs used in this study were conducted in four major universities three of which in Canada and USA. The analytical model used in this study for finite element verification of the results is a three storey building that is adopted from a previous study on SPSW structures which was based on SAC buildings. It was found that the overstrength factor of a multistorey SPSW structure can be estimated by that of only the first storey of that. Also the results for the overstrength factor are not that sensitive to the angle of tension field in the plate. Moreover, it was found that this factor decreases with a decrease of plate thickness and the yield stress of the plate.}, Keywords = {Steel plate shear walls,over-strength factor,plate-frame-interaction,pushover analysis}, volume = {12}, Number = {4}, pages = {63-78}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-11725-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-11725-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Rahgozar, Mohammad Ali}, title = {Evaluation of overstrength factor for steel plate shear wall structures}, abstract ={Steel plate shear walls are very effective lateral load resisting systems which have high lateral stiffness and high ductility capacity at the same time. Although there are valuable experimental data available for such systems, most of the current seismic codes (including Iran’s Standard NO. 2800) provide none or limited design provisions for such structural systems. One of the important seismic performance parameters of the structures is “over-strength factor” which is implicitly or explicitly part of seismic design base shear formulation. Most of the available data on this factor are obtained from experimental research and therefore results are limited to low-rise structures and/or with reduced scaled structures/specimens. The main objective in this research is to assess the over-strength factor for the steel plate shear walls. A closed-form-solution is proposed for obtaining this factor based on a plate-frame interaction. This formulation is on the basis of the assumption that steel plate yields first and then the frame undergoes into the inelastic range. Therefore, an important factor that controls the amount of overstrength in an steel plate shear wall panel is the ratio of the steel plate yield displacement to the that of the steel frame. The lower this ratio is the higher the overstrength factor would be. The results of four experiments from four different universities accross the world were considered. The results also include the geometric and material properties of the specimens as well as their hystresis behaviors under cyclic loading. From the hystresis loops one can obtain experimental overstrength factors. It was found that the over-strength factors obtained by this proposed method are in line with available experimental results obtained from these four tests. It was also found that as the steel plate thickness decreases, the overstrength factor increases. Also, as yield stress of the steel plare decreases, the overstrength factor increases. In other words, the softer the steel plate /panel becomes, the better the chance of the redistribuition of internal forces would be and therefore the higher the overstrength factor would become. Two sets of results and/or comparisons are made in this study. First for the purpose of vrification of the proposed closed form solution, one of the test specimens were extended and it was shown that for the certain condition of that the test the proposed formulation matched the experimental results however if the plate thickness were to increase the overstrength factor would drastically decreases. The second set of results were for steel plate/panels with real sizes and not small lab sizes. It was shown that for such moderate and realistic steel panel sizes and thicknesses the overstrength factor comes out to be about 1.3. In addition, an square like panel has the highest overstrength factor compared to a rectangle ones.}, Keywords = {over-strength factor,plate-frame-interaction,pushover analysis,steel shear walls}, volume = {12}, Number = {4}, pages = {63-78}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-9938-en.html}, eprint = {}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Khanzadi, M. and Chalekaee, A.}, title = {Property Improvement of Iranian LWAC: Investigation of Mechanical Properties and Stress-Strain Curve}, abstract ={The potential use of leca and scoria aggregates available in Iran to produce high strength lightweight concrete has been studied. As a result of various concrete mixes with different lightweight aggregate amount, and using normal techniques, it was possible to obtain high quality lightweight concrete which is suitable for application in reinforced and prestressed concrete structures.In order to investigate the mechanical short term properties of this type of high strength concrete, different tests had done. The properties obtained include unit weight, compressive strength, static modulus of elasticity and poisson's ratio.Among the 28 day aged tested specimens, we could produce HSLWC containing scoria with 55 MPa compressive strength and 2070 kg/m3 weight.In LWC containing leca, a cube compressive strength of about 41 MPa with a unit weight of 1865 kg/m3 was reported.Static modulus of elasticity in concretes containingleca was between 15 to 19 GPa. It was between 17 to 19.5 GPa forconcretescontainingscoria. Some equations were offered to estimate static modulus of elasticity of these concretes based on their compressive strength and unit weight. The mechanical properties were improved by reducing the amount of lightweight aggregate. The results show that both scoria and leca were effective in improving the mechanical properties, but scoria could reach superior limits.Stress- strain curves of investigated concretes were studied and some recommendations are presented for estimating the curves.Stress-strain curves of investigated concretes are almost linear in ascending and descending branch.According to the observed coefficients, withincrease in concrete strength, the slope of the curve is reducedin comparison with modulus of elasticity. For scoria, the slope of curve is lower than modulus in all three mix designs, because of the higher modulus of elasticity of scoria aggregates, in comparison with leca.}, Keywords = {lightweight aggregate concrete,stress-strain curve,leca,scoria,Mechanical Properties}, volume = {12}, Number = {4}, pages = {79-89}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-12154-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-12154-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Khanzadi, Mostafa and Chalekaee, Alirez}, title = {PROPERTY IMPROVEMENT OF IRANIAN LWAC:INVESTIGATION OF MECHANICAL PROPERTIES AND STRESS-STRAIN CURVE}, abstract ={The potential use of leca and scoria aggregates available in Iran to produce high strength lightweight concrete has been studied. As a result of various concrete mixes with different lightweight aggregate amount, and using normal techniques, it was possible to obtain high quality lightweight concrete which is suitable for application in reinforced and prestressed concrete structures, with a compressive strength higher than 40MPa at 28 days. In order to investigate the mechanical short term properties of this type of high strength concrete, different tests had done. The properties obtained include unit weight, compressive strength, splitting tensile strength, static modulus of elasticity and poisson's ratio. And, some relationships were given to estimate modulus of elasticity and splitting tensile strength of these concretes based on their compressive strength. The mechanical properties were improved by reducing the amount of lightweight aggregate. The results show that both scoria and leca were effective in improving the mechanical properties, but scoria could reach superior limits. Stress- strain curves of investigated concretes were studied and some recommendations are presented for estimating the curves. Based on results, curves were almost linear in ascending and descending branch.}, Keywords = {stress-strain curve,leca,scoria,Mechanical Properties,lightweight aggregate concrete}, volume = {12}, Number = {4}, pages = {79-89}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-8252-en.html}, eprint = {}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {Khodadi, A. and Ayati, B. and Bineshian, F.}, title = {Bacteriological Modelling of Semnan Drinking Water Distribution}, abstract ={Microbial quality of potable water is of the most import guidelines of the World Health Organization (WHO). One of the main concerns of water supply and distribution network problems particularly in large cities is microbial growth in the pipelines that are significant non-compliers and repeatedly detect bacteria in finished drinking-water. In Iran, chlorine is mostly used as disinfection agent in conventional chemical treatment process in water treatment plants for supplying safe drinking water. This is done to maintain a residual concentration within a water distribution system for preventing the growth of pathogenic bacteria. Therefore, to meet water quality standards, it is necessary to maintain free chlorine residuals throughout the minimum and maximum levels for various reasons. This study was conducted to examine the relationship between residual chlorine concentration, turbidity and microbial quality of water used for drinking in water distribution system of city of Semnan. Heterotrophic Plate Count (HPC) bacteria was used as an indicator for microbial quality and residual chloride concentration and turbidity were selected as the main parameters for determining correlation. In this research, for the first time Water-Gems as a comprehensive and easy-to-use water distribution modeling application bacteriological software with GIS system was employed as a tool to evaluate the microbial water quality in the network of Semnan city which is known as drawn area with limited water resources. Water-Gems is a multi-platform hydraulic and water quality modeling solution for water distribution systems with advanced interoperability, geospatial model-building, optimization, and asset management tools. For the study, all required information from water supply system such as topographical references, type and diameter of pipelines, pressure head in the system and connections were imported in the software. Then sampling points were selected and 25200 samples were made for turbidity, residual chloride concentration and HPC bacteria. The results indicated that there is high correlation between free chloride residual, turbidity and HPC which means that lower chloride concentration caused the increase in turbidity and HPC number. This information can be used to formulate a bacterial growth control strategy.}, Keywords = {Microbial Water Quality Control,Residual Chlorine Concentration,HPC}, volume = {12}, Number = {4}, pages = {91-98}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-2459-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-2459-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} } @article{ author = {KomakPanah, A. and Gangali, E.}, title = {Investigation on the Effect of Specimen Size and Degradation of the Soils in the Strength Parameters in Direct Shear Test}, abstract ={Although direct shear test has some limitations in test procedure and test results, still it is one the popular and prevalent test which is used in most laboratories for evaluation of shear strength parameters of soils. Most of direct shear test apparatus in laboratories are in the specimen dimensions ranging from 6*6 to 10*10 centimeters. There are very limited number of large direct shear apparatus in soil mechanics laboratories with specimen dimensions of 30*30 or larger. In order to perform direct shear tests on coarse graded materials, it is recommended to degrade material to finer gradation accepted by test standards relative to the box dimensions. It is clear that degradation by using exclusion or parallel method increases fine contents of soil samples in small shear boxes. When shear tests are performed on fine graded soil samples, the strength parameters become different from those of original coarse graded samples. Therefore it is necessary to investigate relation between these different parameters. The aim of this research is to compare the test results between shear strength parameters derived from both small and large direct shear tests. Three soil samples with 5,15 and 25 percent fine contents with three 80,90 and 100 percent relative densities were tested in large and small direct shear apparatus with box dimensions of 30*30*15 and 6*6*2.5 centimeters. Shear parameters were derived and compared carefully. The results indicated that degradation has great effect on the parameters. Also it was found out that degration by parallel method compared with exclusion method gives smaller parameters. It seams that the discrepancy is the result of fine content differences.             Comparing the fine contents in two samples prepared using both methods indicates that the fine content in samples produced by parallel method have greater amount.             Comparing resulting internal friction angles of original coarse graded material tested in large apparatus with the friction angles calculated from small degraded samples give larger values in the same relative densies. The increments are 2.5 degrees for degradation using exclusion method and 4.5 to 6 degrees using parallel method. Also the test result showed that the amount of increments increase in samples with higher amount of fine contents}, Keywords = {Direct shear,Specimen size,degradation,Shear stremght}, volume = {12}, Number = {4}, pages = {99-106}, publisher = {Tarbiat Modares University}, url = {http://mcej.modares.ac.ir/article-16-4897-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-4897-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2012} }