OTHERS_CITABLE Endurance Time (ET) method is a response history based analysis procedure that can be used for estimating the seismic response of structures at different excitation levels in each response history. This seismic analysis method utilizes specific intensifying acceleration functions to analyze seismic behaviors. One of the potential applications of the ET method is in the seismic assessment of shell structures. In this study, a procedure for linear seismic analysis of shell structures is proposed and applications of this method is investigated for several cases of shell structures. These structures are analyzed under three ET acceleration functions in one direction and the results are compared to time history analysis considering seven actual earthquake records. Moreover, the results of the ET method are compared to response spectrum analysis method. The outcomes of the study reveal that the ET method predicts the linear seismic performance of shell structures with acceptable precision and significant reduction in analysis time. Furthermore, it is conluded that scattering of results of three ET analysis is very low and one analysis can be used instead of three. Finally, the comparison between THA and RSM results verify that response spectuarm method is a conservative method which occasionally encounters problems to evaluate bending stresses of shell structures http://ijce.iust.ac.ir/article-1-559-en.pdf 2015-10-22 169 178 Endurance time method Shell structures Time history analysis Response spectrum analysis H. Tavazo hatavazo@yahoo.com 1 Department of Civil Engineering, Sharif University of Technology, Tehran, Iran AUTHOR H. E. Estekanchi stkanchi@sharif.edu 2 Associate Professor, Department of Civil Engineering, Sharif University of Technology, Tehran, Iran AUTHOR P. Kaldi kaldi@mapnamd2.com 3 Supervisor of MAPNA Combined Cycle Power Plant Construction & Development Co. (MD2), MAPNA Group(Civil & Structure Manager of MD2 Co.) AUTHOR

OTHERS_CITABLE Due to the algorithmic simplicity, cellular automata (CA) models are useful and simple methods in structural optimization. In this paper, a cellular-automaton-based algorithm is presented for simultaneous shape and topology optimization of continuum structures, using five-step optimization procedure. Two objective functions are considered and the optimization process is converted to the single objective optimization problem (SOOP) using weighted sum method (WSM). A novel triangle neighborhood is proposed and the design domain is divided into small triangle elements, considering each cell as the finite element. The finite element formulation for constant strain triangles using three-node triangular elements is developed in this article. Topological parameters and shape of the design space are taken as the design variables, which for the purpose of this paper are continuous variables. The paper reports the results of several design experiments, comparing them with the currently available results obtained by CA and genetic algorithm in the literature. The outcomes of the developed scheme show the accuracy and efficiency of the method as well as its timesaving behavior in achieving better results http://ijce.iust.ac.ir/article-1-515-en.pdf 2015-10-22 179 188 Cellular automaton Structural optimization Topology Shape Constant Strain triangle (CST) E. Sanaei ebrahimsanaei@yahoo.com 1 1Full Professor in Structural Engineering, Department of Civil Engineering, AUTHOR M. Babaei mbabaei@iust.ac.ir 2 2Ph.D. Student in Structural Engineering, Department of Civil Engineering, AUTHOR

OTHERS_CITABLE In this paper a discrete Big Bang-Big Crunch algorithm is applied to optimal design of reinforced concrete planar frames under the gravity and lateral loads. Optimization is based on ACI 318-08 code. Columns are assumed to resist axial loads and bending moments, while beams resist only bending moments. Second-order effects are also considered for the compression members, and columns are checked for their slenderness and their end moments are magnified when necessary. The main aim of the BB-BC process is to minimize the cost of material and construction of the reinforced concrete frames under the applied loads such that the strength requirements of the ACI 318 code are fulfilled. In the process of optimization, the cost per unit length of the sections is used for the formation of the subsequent generation. Three bending frames are optimized using BB-BC and the results are compared to those of the genetic algorithm. http://ijce.iust.ac.ir/article-1-572-en.pdf 2015-10-22 189 200 Optimization Reinforced concrete plane frame Big Bang-Big Crunch algorithm A. Kaveh alikaveh@iust.ac.ir 1 Professor, Centre of Excellence for Fundamental Studies in Structural Engineering, Iran University of Science and Technology,Narmak, Tehran, Iran AUTHOR O. Sabzi omid_sabzi@civileng.iust.ac.ir 2 M.Sc. Department of Civil Engineering, Iran University of Science and Technology, Tehran-16, Iran AUTHOR

OTHERS_CITABLE One important application of fiber reinforced polymer (FRP) is to confine concrete as FRP jackets in seismic retrofit process of reinforced concrete structures. Confinement can improve concrete properties such as compressive strength and ultimate axial strain. For the safe and economic design of FRP jackets, the stress-strain behavior of FRP-confined concrete under monotonic and cyclic compression needs to be properly understood and modeled. According to literature review, it has been realized that although there are many studies on the monotonic compressive loading of FRP-confined concrete, only a few studies have been conducted on the cyclic compressive loading. Therefore, this study is aimed at investigating the behavior of FRP-confined concrete under cyclic compressive loading. A total of 18 cylindrical specimens of FRP-confined concretewere tested in uniaxial compressive loading with different wrap thickness, and loading patterns. The results obtained from the tests are presented and examined based on analysis of test results predictive equations for plastic strain and stress deterioration were derived. The results are also compared with those from two current models,comparison revealed the lack of sufficient accuracy of the current models to predict stress-strain behavior and accordingly some provisions should be incorporated. http://ijce.iust.ac.ir/article-1-527-en.pdf 2015-10-23 201 209 Confined concrete Stress-strain behavior Fiber reinforced polymer Cyclic loading R. Abbasnia abbasnia@iust.ac.ir 1 Department of Civil Engineering, Iran University of Science and Technology, Tehran, Iran AUTHOR A. Holakoo aholakoo@gmail.com 2 Department of Civil Engineering, Iran University of Science and Technology, Tehran, Iran AUTHOR

OTHERS_CITABLE Self-desiccation is the major source of autogenous shrinkage and crack formation in low water-binder ratio (w/b) concretes which can be reduced by internal curing. In this paper performance of high strength self consolidating concrete (HS-SCC) with w/b of 0.28 and 0.33 including autogenous shrinkage, drying shrinkage, compressive strength, and resistance to freezing-thawing was investigated. Then, for the purpose of internal curing, 25% of normal weight coarse aggregate volume was replaced with saturated lightweight aggregate (LWA) of the same size and its effects on the material properties was studied. Two modes of external curing, moist and sealed, were applied to test specimens after demoulding. Autogenous shrinkage from 30 minutes to 24 hours after mixing was monitored continuously by a laser system. The initial and final setting time were manifested as a change of the slope of the obtained deformation curves. Shrinkage after initial setting was 860 and 685 microstrain (;mu;epsilon) for 0.28 and 0.33 w/b mixtures, respectively. The saturated LWA reduced these values to 80 and 295 ;mu;epsilon, respectively. By LWA Substitution the 28- day compressive strength of 0.28 w/b mixture was reduced from 108 to 89 and 98 to 87 MPa for moist and sealed cured specimen, respectively. The corresponding values for 0.33 w/b mixture was 84 to 80 and 82 to 70 MPa. Shrinkage of 0.28 w/b mixture without LWA after moist and sealed cured specimen dried for 3 weeks was about 400 ;mu;epsilon. Shrinkage of moist and sealed cured specimen containing LWA was reduced 9% and 25%, respectively. On the contrary for 0.33 w/b mixture an increase was noticed. Freezing-thawing resistance was improved by sealed curing, decreasing w/b and substituting LWA. http://ijce.iust.ac.ir/article-1-597-en.pdf 2015-10-22 210 221 High strength self consolidating concrete Autogenous shrinkage Drying shrinkage internal curing Saturated lightweight aggregate Freezing-thawing resistance H. Famili hormoz.famili@gmail.com 1 Assistant Professor, Civil Engineering Department, Iran University of Science and Technology, Tehran, Iran AUTHOR M. Khodadad Saryazdi mkhodadad@yazduni.ac.ir 2 Instructor, Civil Engineering Department, Yazd University, Yazd, Iran AUTHOR T. Parhizkar 3 Assistant Professor, Building and Housing Research Center of Iran, Tehran, Iran AUTHOR

OTHERS_CITABLE The application of fuzzy algorithms in the response control of a base isolated building with MR dampers is investigated in this paper. Most of the previous researches in this field have been focused on fuzzy algorithms with linear membership function however in the current study the membership functions are assumed to be Gaussian and their effectiveness is studied. For this purpose, an eight-story building with regularity in plan and height is considered. The adopted base isolation system includes linear bearings and control devices for improving the behavior of isolated structure under near field ground motions. MR dampers are used to reduce base displacements and have the capacity of 1000 kN with the maximum applied voltage of 10 V. In order to verify the control procedure and analyzing the structure, a simulation procedure is developed. This procedure performs linear analysis of the structure in presence or in absence of the base isolation system. Moreover, the simulation procedure is able to appropriately determine the MR damper voltage using fuzzy logic algorithms and then analyzing the whole system too. Finally, seven near-field earthquake records are chosen in order to study the structure responses under these records and the obtained results demonstrate the accuracy of proposed control procedure http://ijce.iust.ac.ir/article-1-504-en.pdf 2015-10-22 222 231 Semi-active control MR damper Near-field earthquakes Base-isolated building Fuzzy control algorithm. A. H. Molavi-Tabrizi amir.molavi@gmail.com 1 MSc graduated, Department of Civil Engineering, Amirkabir University of Technology, Hafez st., Tehran, Iran AUTHOR F. Khoshnoudian khoshnud@aut.ac.ir 2 Associate professor, Department of Civil Engineering, Amirkabir University of Technology, Hafez st., Tehran, Iran AUTHOR

OTHERS_CITABLE The torsional capacity of unreinforced masonry brick buildings is generally inadequate to provide a stable seismic behavior. The torsional strength is believed to be the most important parameter in earthquake resistance of masonry buildings and the shear stresses induced in the bed joints of such building’s walls is an important key for design purposes. Brick buildings strengthened with wire-mesh reinforced concrete overlay are used extensively for building rehabilitation in Iran. Their quick and simple applications as well as good appearance are the main reasons for the widespread use of such strengthening technique. However, little attention has been paid to torsional strengthening in terms of both experimental and numerical approach. This paper reports the response and behavior of two single-story brick masonry buildings having a rigid two-way RC floor diaphragm. Both specimens were tested under monotonic torsional moment.Numerical work was carried out using non-linear finite element modeling. Good agreement in terms of torque–twist behavior, and crack patterns was achieved. The unique failure modes of the specimens were modeled correctly as well. The results demonstrate the effectiveness of reinforced concrete overlay in enhancing the torsional response of strengthened building. Having evaluated the verification of modeling, an unreinforced brick building with wall-to-wall vulnerable connections was modeled so that the effect of these connections on torsional performance of brick building could be studied. Then this building was strengthened with reinforced concrete overlay and the effect of strengthening on torsional performance of brick buildings with vulnerable connections was predicted numerically. http://ijce.iust.ac.ir/article-1-481-en.pdf 2015-10-22 232 244 Brick building Numerical micro-modeling Strengthening Torsional behavior Vulnerable connection A. A. Tasnimi tasnimi@modares.ac.ir 1 Professor in Structural Eng., Faculty of Civil and Environmental Eng., TarbiatModares University, Tehran, Iran AUTHOR M. A. Rezazadeh rezazadeh_1984@yahoo.com 2 MSc. Student, Faculty of civil and Environmental Eng.,TarbiatModaresUniversity,Tehran, Iran AUTHOR