Sharif University of TechnologyScientia Iranica1026-309821420140801Effect of Turbulence Closure Models on the Accuracy of Moving Particle Semi-implicit Method for the Viscous Free Surface FlowEffect of Turbulence Closure Models on the Accuracy of Moving Particle Semi-implicit Method for the Viscous Free Surface Flow121712301717ENM. KolahdoozanDepartment of Civil & Environmental Engineering, Amirkabir University of Technology, Tehran, IranM.S. AhadiDepartment of Civil & Environmental Engineering, Amirkabir University of Technology, Tehran, IranS. ShirazpoorDepartment of Civil & Environmental Engineering, Amirkabir University of Technology, Tehran, IranJournal Article20140223The purpose of this paper is to put forward the effect of different turbulence closer models on an enhanced Moving Particle Semi-implicit (MPS) method for solving continuity and momentum equations of viscous fluid. MPS method is a mesh- free Lagrangian method capable of solving non-linear governing equations and simulating complex free surface flow circumstances. Various turbulence closer models are added to a MPS program and applied it to different fluid mechanic problems to investigate the effect of these types of closure. Dam break simulation outcome indicates that two-equation turbulence model improves free surface estimation accuracy most. It also shows that type of utilized Kernel function has no significant efficacy on stability when the effect of turbulence is included. Further, an algorithm called Incomplete Conjugate Cholesky Gradient (ICCG) is applied for computing pressure implicitly. Applying developed model to well-known sample problems cited in the literature represents that using turbulence closure models can enhance the prediction of developed model as well as stability of the simulations.Sharif University of TechnologyScientia Iranica1026-309821420140801Study on the failure behavior of three dierent stabilized problematic soilsStudy on the failure behavior of three dierent stabilized problematic soils123112401718ENE. AflakiDepartment of Civil Engineering, Amirkabir University of Technology, Tehran, IranE. AflakiDepartment of Civil Engineering, Amirkabir University of Technology, Tehran, IranP. SedighiDepartment of Civil Engineering, Central Teharn Branch, Islamic Azad University, Tehran, IranA. EslamiDepartment of Civil Engineering, Amirkabir University of Technology, Tehran, IranJournal Article20140906In this study laboratory testing of eectiveness of cement treatment has been made on geotechnical parameters of problematic soils encountered in southern coast line of Caspian Sea, Iran. Gorgan loess, Rasht clay, and Anzali sand were selected in this research. Addition of cement was found to improve workability and increased unconned compressive strength, and elastic modulus of soils signicantly. Triaxial test results indicated that cement treatment not only improved shear strength remarkably, but also it changed the type of failure greatly from ductile to brittle behavior. The large scale direct shear test results showed signicant improvement in shear strength and shear modulus. Besides, the brittle behavior of cement treated samples was observed. Eventually, it was found that the trend of failure envelope of cement treated samples was non-linear, and some failure criteria such as modied Grith theory, Hoek-Brown theory, and the Johnston criterion can describe the soil cement behavior satisfactorily.Sharif University of TechnologyScientia Iranica1026-309821420140801THE LEADERSHIP PROFILE OF NIGERIAN CONSTRUCTION PROJECT MANAGERSTHE LEADERSHIP PROFILE OF NIGERIAN CONSTRUCTION PROJECT MANAGERS124112481719ENO. J. AMEHSenior Lecturer, Department of Building, University of Lagos, Akoka, Yaba, Lagos NigeriaK. T. ODUSAMIDepartment of Building, University of Lagos, Akoka, Yaba, Lagos NigeriaJournal Article20131106The study aimed at presenting the leadership characteristics of Nigerian construction professionals involved as team leaders on building projects. Sixty construction project managers who were based in the Nigerian cities of Lagos and Abuja were selected for the study. A questionnaire was designed to collect data on 11 variables pertaining to the leaders including professional grouping, age, educational and professional qualifications, industrial experience, overseas training, overall training, personality, leadership style, style range and effectiveness. Descriptive statistics were used for the analysis of the data obtained. One way analysis of variance and Chi-square were used to test the study hypotheses. Notable findings include: Majority of the project leaders exhibited consensus leadership style, overwhelming majority style range support high task/high relationship behaviour;there was no significant relationship between the project leader’s professional background and his leadership style, and there was no significant relationship between project leader’s professional background and effectivenessSharif University of TechnologyScientia Iranica1026-309821420140801Nonlinear nite element analysis of RC beams under combined shear and torsion to extract linear and curvilinear ranges of interaction curvesNonlinear nite element analysis of RC beams under combined shear and torsion to extract linear and curvilinear ranges of interaction curves124912621720ENS.B. TalaeitabaAzad University, Department of Civil Engineering, Isfahan University of Technology, P.O. Box 8415683111, Isfahan, IranM.E. TorkiDepartment of Aerospace Engineering, Texas A&M University, College Station, TX 77843, USA.Journal Article20140906Nonlinear nite element analysis of RC beams under combined shear and torsion to extract linear and curvilineThe use of non-linear nite elements to assess the eect of transverse reinforcement amount on the shape of shear-torsion interaction curve for RC beams is addressed. At rst, FEM results for specimens under pure torsion and combined shear and torsion were validated with previous outcomes. Secondly, reference specimens were made with the minimum required transverse reinforcement at rst. Each specimen was analyzed with the nite element method and tested under similar conditions in the laboratory, and the results, including the cracking pattern, cracking and ultimate loads, and shear-torsion interaction curves, were found to be in very good agreement. Finally, the transverse reinforcement amount was increased to certain extents and similar results were determined. FEM interaction curve stood below the experimental curve. It was also deduced that, from a certain increase in the transverse reinforcement, the shear-torsion interaction curve transforms from linear to elliptical.ar ranges of interaction curves Sharif University of TechnologyScientia Iranica1026-309821420140801Rate-Dependence of Rockfill Behavior on Propagated Near Fault Ground MotionsRate-Dependence of Rockfill Behavior on Propagated Near Fault Ground Motions126312801721ENHamid-Reza RazeghiSchool of Civil Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran, P.O. Box 16765-163, IranAta Aghaei AraeiHead of Geotechnical Engineering Lab., Road, Housing and Urban Development Research Center (BHRC), Tehran, P.O. Box:13145-1696, IranAbbas GhalandarzadehSchool of Civil Engineering, College of Engineering, University of Tehran, P.O. Box 11365-4563, IranSaeid Hashemi TabatabaeiDepartment of Geotechnical Engineering, Road, Housing and Urban Development (BHRC), Tehran, P.O. Box:13145-1696, IranJournal Article20131015Equivalent linear one-dimensional site response analysis, which approximates the nonlinear soil behavior within the linear analysis framework, is widely used in estimating local site effects. In this analysis, soil behavior is often assumed to be independent of the frequency of seismic loading. However, the large scale triaxial test results on rockfill material have shown that the shear modulus, and especially the damping ratio, are influenced by the loading frequency. A series of one-dimensional equivalent linear analyses were performed on 30m and 90m thick profiles of the studied rockfill material to evaluate the frequency-dependent soil behavior under several well-known near-fault ground motions. The analyses are carried out for three base acceleration levels, namely, 0.1 g, 0.35 g, and 1 g, using the simple time history scaling method. Results show that the frequency-dependent shear modulus and damping ratio can have a pronounced influence on propagated ground motions. The frequency-dependent soil behavior is also dependent on the thickness of soil profile,amplitude, equivalent no. of cycles at 0.65τmax, and frequency content of the input ground motion.Sharif University of TechnologyScientia Iranica1026-309821420140801Influence of Fines Content and Type on the Small-2 strain Shear Modulus of SandInfluence of Fines Content and Type on the Small-2 strain Shear Modulus of Sand128112961722ENNima Akbari PaydarGeotechnical Engineering, Dept. of Civil Engineering, Sharif University of Technology, Tehran, IranMohammad Mehdi AhmadiGeotechnical Engineering Group, Dept. of Civil Engineering, Sharif University of Technology, Tehran, IranJournal Article20131118Small-strain shear modulus, G0, is an important fundamental soil property. Although many studies have been conducted on this property for clean sands and pure clays,small-strain behavior for mixtures of sand and fines has been less addressed. Thispaper presents the results of a comprehensive laboratory study on G0 value of sandcontaining various amounts of different fines. To this aim, bender elements wereintegrated into a conventional triaxial apparatus, and shear wave velocity wasmeasured on samples of sand with different amounts of highly-plastic, medium- plastic, low-plastic, or non-plastic fines at different void ratios. Measuring the shearwave velocity and thus obtaining G0 at different void ratios and effective stresses, theintrinsic parameters that characterize G0 were determined for the tested materials.This allowed the effects of fines type and content on the G0 value of sand to beevaluated in a systematic manner. The G0 values of different sand-fines mixtureswere compared based on different density parameters. Results show that G0 of siltyand clayey sands is affected by both fines content and fines type. Therefore, in orderto estimate G0 of sand-fines mixture, not only the fines content but also theirplasticity needs to be properly accounted.Sharif University of TechnologyScientia Iranica1026-309821420140801Shape Optimization of Concrete Arch Dams considering Abutment StabilityShape Optimization of Concrete Arch Dams considering Abutment Stability129713081723ENMeisam TakalloozadehCivil Engineering Department, Sharif University of Technology, Tehran, IranMeisam TakalloozadehCivil Engineering Department, Sharif University of Technology, Tehran, IranMohsen GhaemianCivil Engineering Department, Sharif University of Technology, Tehran, IranJournal Article20140607A novel and robust approach is proposed to find the optimum shape of concrete arch dams located on any unsymmetrical shape of the valley. The approach is capable to find the optimum shape for any given valley type in suitable time based on the abutment stability analysis against thrust forces from arch dam. The behavior and stability of the concrete arch dam is strongly dependent on the bedrock that dam rests on it. Stability of abutment is considered as a constraint in proposed approach. In addition a new objective function is introduced to decrease the final volume of the arch dam. Furthermore, a computer program was developed which can take effect of the dam foundation system into consideration and can model the most loads that applied to arch dams. The optimization problem is solved via both the Particle Swarm Optimization (PSO) and classical methods. Several practical factors have been considered to make the approach more feasible and effective in practical projects. The results show the efficiency of the proposed method and the final shape satisfy all constraints.Sharif University of TechnologyScientia Iranica1026-309821420140801Improved Support Vector Machine Regression in Multi-Step-Ahead Prediction for Tunnel Surrounding Rock Displacement Improved Support Vector Machine Regression in Multi-Step-Ahead Prediction for Tunnel Surrounding Rock Displacement 130913161724ENBaozhen YAO School of Automotive Engineering, Dalian University of Technology, Dalian, 116024, P.R.China Baozhen YAO School of Automotive Engineering, Dalian University of Technology, Dalian, 116024, P.R.China Baozhen YAO School of Automotive Engineering, Dalian University of Technology, Dalian, 116024, P.R.China Jinbao YAO School of Civil Engineering & Architecture, Beijing Jiaotong University, Beijing, 100044, P.R.ChinaJinbao YAO School of Civil Engineering & Architecture, Beijing Jiaotong University, Beijing, 100044, P.R.ChinaJinbao YAO School of Civil Engineering & Architecture, Beijing Jiaotong University, Beijing, 100044, P.R.ChinaMingheng ZHANG School of Automotive Engineering, Dalian University of Technology, Dalian, 116024, P.R.China Lan YU Yanching Institute of Technology, Beijing, 100044, 065201 P.R.ChinaLan YU Yanching Institute of Technology, Beijing, 100044, 065201 P.R.ChinaLan YU Yanching Institute of Technology, Beijing, 100044, 065201 P.R.ChinaJournal Article20131127A dependable long-term prediction of tunnel surrounding rock displacement is an effective way to predict the rock displacement values into the future. A multi-step-ahead prediction model, which is based on support vector machine (SVM), is proposed for tunnel surrounding rock displacement prediction. To improve the performance of SVM, parameter identification is used for SVM. In addition, to treat with the time-varying features of tunnel surrounding rock displacement, a forgetting factor is introduced to adjust the weights between new and old data.At last, the data from the Chijiangchong tunnel are selected to examine the performance of the prediction model. Comparative results were presented between SVMFF (SVM with a forgetting factor) and artificial neural network with a forgetting factor (ANNFF) show that SVMFF is generally better than ANNFF. This indicates that a forgetting factor can effectively improve the performance of SVM, especially for the time-varying problems.Sharif University of TechnologyScientia Iranica1026-309821420140801Exploring the opportunities for Reuse of municipal Construction and Demolition (C&D) wastes in concreteExploring the opportunities for Reuse of municipal Construction and Demolition (C&D) wastes in concrete131713241725ENAttaullah ShahProject Director Project Directorate, Allama Iqbal Open University Islamabad PakistanIrfan.U. JanNational Centre of Excellence in Geology University of Peshawar-Pakistan Razaullah KhanSenior Scientific Officer National Agricultural Research Council ( NARC) Islamabad PakistanEhsan.U. QaziDeputy Director General National Institute of Science and Technical Education ( NISTE) Islamabad Pakistan Journal Article20131201The sustainable practices in the built environment are based on conservation of resources, such as minimum use of material, energy and water. Disposal of construction waste poses major challenge to the municipal administration of the developing countries. The fast urbanization and rapid construction in these countries has generated substantial volume of construction wastes. There are many options for the disposal of construction wastes. One of such options is to utilize these wastes as aggregates for concrete. The reuse of such aggregates in the concrete would reduce the disposal costs of construction wastes on one hand and burden on natural resources in terms of resource harvesting on the other hand. In this research work, the construction wastes collected from the municipal sources have been segregated, graded and utilized as aggregates in cement concrete. Considering different percentages of recycled aggregates, various concrete mixtures were prepared and tested to determine their compressive strengths for evalauating suitability of the concrete mixtures for construction purposes. The test results indiacte that the recycled aggregates can be used for producing plain concrete mixtures for mass concreting and construction of pavements and walkways.Sharif University of TechnologyScientia Iranica1026-309821420140801Effect of SiC on microstructural features and compressive properties of aluminum foamEffect of SiC on microstructural features and compressive properties of aluminum foam132513291726ENM. MalekjafarianMaterials Research Group, Iranian Academic Center for Education, Culture and Research (ACECR), Mashhad Branch, P.O. Box 91775-1376, Azadi Square, Mashhad, IranS.K. SadrnezhaadDepartment of Materials Science and Engineering, Sharif University of Technology0000-0003-2631-5863Journal Article20131118Composite aluminum-SiC foam was manufactured by injection of air and addition of reinforcement particles into the liquid aluminum. Microstructure and mechanical properties of the Al/SiC foams were investigated by scanning electron microscopy and compression tests. Results showed that both the cell size and the wall thickness augmented with increasing of the SiC reinforcement particles; while SiC particles resulted in the reduction of the plateau border length. With more SiC particles, plateau stress became larger; but maximum plateau strain became smaller. The stress-strain curves exhibited serrations in the plateau region due to addition of the SiC particles.Sharif University of TechnologyScientia Iranica1026-309821420140801Centrifuge modeling of pile-soil-pile interaction mconsidering relative density and toe conditionCentrifuge modeling of pile-soil-pile interaction mconsidering relative density and toe condition133013391727ENA. Saeedi AzizkandiSchool of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.M.H. BaziarSchool of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.M. ModarresiSchool of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.H. SalehzadehSchool of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.H. RasouliSchool of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.Journal Article20140906In a group of installed piles, the stresses applied from one pile to soil may have overlaps with another pile which leads to the changes in bearing capacity and settlement of each individual pile. In order to predict the performance of those piles, interaction coecients, based on elasticity theory proposed by Mindlin, are widely applied. In this paper, the eect of soil relative density and also toe condition on the interaction between two similar piles in sandy soil is presented using centrifuge modeling. To achieve this objective, 22 tests have been conducted to investigate the eect of soil relative density and another 11 tests were performed to study the contribution of pile toe and shaft in the interactions. The results showed that the value of soil relative density has an important role in the coecient of interaction which has not been considered in previously reported correlations. For this reason a modication has been proposed for the Randolph and Wroth equation to consider soil relative density. Accuracy prediction of the new modelwas compared with the Randolph and Wroth equation with the aid of dierent statistical parameters. This comparison indicated the superiority of the proposed model over previous methods.Sharif University of TechnologyScientia Iranica1026-309821420140801Structural damage identification based on incomplete static responses as an optimization problem120912162141210.24200/sci.2014.21412ENS.S. KourehliDepartment of Civil Engineering, College of Engineering, Ahar Branch, Islamic Azad University, Ahar, Iran.A. BagheriDepartment of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USAG. Ghodrati AmiriCenter of Excellence for Fundamental Studies in Structural Engineering, School of Civil Engineering, Iran University of Science and Technology, Tehran, IranM. Ghafory-AshtianyStructural Department, International Institute of Earthquake Engineering and Seismology, Tehran, IranJournal Article20120316Damage detection and estimation in structures using incomplete static<br />responses are presented in this study. In the proposed approach, damage location and<br />severity is determined by solving an optimization problem using a pattern search algorithm.<br />Therefore, an objective function is formulated using incomplete static responses. Because<br />of limitations in using sensors and diculties in sensing all degrees of freedom, the eect of<br />using incomplete responses has been evaluated. The performance of the proposed method<br />was evaluated using three numerical examples, namely, a simply supported beam, a threestory<br />plane frame, and a plane bridge with and without noise in measured displacement<br />and containing one or several damages. The results indicate that the proposed method is<br />eective and robust in the detection and estimation of damage in spite of the incomplete<br />responses.