@article{ author = {Xu, Jiuping and Wei, Pei}, title = {A bi-level model for location-allocation problem of construction & demolition waste management under fuzzy random environment}, abstract ={In this paper, a location allocation (LA) problem in construction and demolition (C;D) waste management (WM) is studied. A bi-level model for this problem under a fuzzy random environment is presented where the upper level is the governments who sets up the processing centers, and the lower level are the administrators of different construction projects who control C;D waste and the after treatment materials supply. This model using an improved particle swarm optimization program based on a fuzzy random simulation (IPSO-based FRS) is able to handle practical issues. A case study is presented to illustrate the effectiveness of the proposed approach. Conclusions and future research directions are discussed.}, Keywords = {Location-allocation optimization, Construction waste management, Fuzzy random, PSO, Bi-level models}, volume = {10}, Number = {1}, pages = {1-12}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-565-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-565-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Behbahani, H. and Yaghoubi, H. and Rezvani, M. A.}, title = {Development of technical and economical models for widespread application of magnetic levitation system in public transport}, abstract ={Magnetic levitation (maglev) is amongst the most advanced technologies that are available to the transportation industries. It has already been noticed by decision makers in many countries around the globe. Contrary to such high levels of interest, there are no practical algorithms available to the engineers and/or managers to assist them in analyzing economics of the maglev systems. Therefore, it has been the purpose of this research to find appropriate answers to such vital questions and also investigate feasibility for practical use of maglev technology in rapid transit systems. The life cycle costs (LCC) for the maglev system including the cost of initiating such projects are included in this survey and are evaluated. To serve the purpose, an algorithm is presented that facilitates the technical and economical analyses of maglev systems. The proposal for a long distance maglev system, Mashhad-Tehran (M-T), is used as a case study by using the proposed algorithm. Moreover, the cost of establishing and operating M-T project is estimated by two other different approaches. These include the already established mathematically based cost estimating method, and the cost estimations based on the international norms and standards. These standards are based on statistical (or provided) data. Such cost estimations assist verification of the proposed algorithm. Comparisons between outcomes of the three methods prove close agreement for the cost estimation by all of them. It is concluded that the proposed algorithm for implementation and operation of maglev route is practical.}, Keywords = {Maglev, Guideway, Life cycle cost, Mathematical models, Cost estimating method}, volume = {10}, Number = {1}, pages = {13-24}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-371-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-371-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Memon, R. A. and Khaskheli, G. B. and Dahani, M. H.}, title = {Estimation of operating speed on two lane two way roads along N-65 (SIBI –Quetta)}, abstract ={Present study is an extension of earlier work carried out on two-lane two way roads in the two provinces of Pakistan i.e. N-25, N-55 and N-5 regarding the measure of operating speed and development of operating speed prediction models. Curved sections of two-lane rural highways are the main location of run-off road accidents. In addition to that the road alignment having combination of geometric elements may be more harmful to the drivers than the successive features with adequate separation. This study is carried out on two-lane two- way road along N-65 (from Sibi to Quetta). Three sections are selected for study with thirty three horizontal curves. Continuous speed profile data was recorded with the help of VBox (GPS based device) which was attached with a vehicle to detect vehicle position through satellite signals. VBox is new equipment with modern technology in this field and it helps in recording continuous speed profile and saving of this information on the computer as a permanent record. Through the regression analysis, models were developed for estimation of operating speed on horizontal curves and on tangent, and estimation of maximum speed reduction from tangent to curve. The validation of developed model shows compatibility with the experimental data.}, Keywords = {Operating speed, Speed profile, Design consistency}, volume = {10}, Number = {1}, pages = {25-31}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-516-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-516-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Kaveh, A. and NasrEsfahani, H.}, title = {Hybrid harmony search for conditional p-median problems}, abstract ={In this paper the conditional location problem is discussed. Conditional location problems have a wide range of applications in location science. A new meta-heuristic algorithm for solving conditional p-median problems is proposed and results are compared to those of the previous studies. This algorithm produces much better results than the previous formulations.}, Keywords = {location problem, p-median problem, conditional, harmony search, meta-heuristics}, volume = {10}, Number = {1}, pages = {32-36}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-469-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-469-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Kaveh, A. and ShakouriMahmudAbadi, A. and ZolfaghariMoghaddam, S.}, title = {An adapted harmony search based algorithm for facility layout optimization}, abstract ={This paper presents a strategy for using Harmony Search algorithm in facility layout optimization problems. In this paper an adapted harmony search algorithm is developed for solving facility layout optimization problems. This method finds an optimal facility arrangement in an existing layout. Two real-world case studies are employed to demonstrate the efficiency of this model. A comparison is also made to illustrate the efficiency of these strategies in facility layout optimization}, Keywords = {Facility layout optimization, Architecture, Adapted harmony search algorithm}, volume = {10}, Number = {1}, pages = {37-42}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-466-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-466-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Shokoohi, A. R. and Saghafian, B.}, title = {A semi analytical solution for rising limb of hydrograph in 2D overland flow}, abstract ={In almost all of the present mathematical models, the upstream subbasins, with overland flow as the dominant type of flow, are simulated as a rectangular plane. However, the converging plane is the closest shape to an actual upstream subbasin. The intricate nature of the governing equations of the overland flow on a converging plane is the cause of prolonged absence of an analytical or semi analytical solution to define the rising limb of the resulted hydrograph. In the present research, a new geomorphologic semi analytical method was developed that tries to establish a relationship between the parallel and converging flows to reduce the complexity of the equations. The proposed method uses the principals of the Time Area method modified to apply the kinematic wave theory and then by applying a correction factor finds the actual discharge. The correction factor, which is based on the proportion of the effective drained area to the analytically calculated one, introduces the convergence effect of the flow in reducing the potentially available discharge in a parallel flow. The proposed method was applied to a case study and the result was compared with that of Woolhiser;#39s numerical method that showed the reliability of the new method.}, Keywords = {Kinematic wave, Converging plane, Parallel flow, Time to equilibrium, Rising limb, Geomorphologic correction factor}, volume = {10}, Number = {1}, pages = {43-50}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-524-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-524-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Behzadian, K. and Alimohammadnejad, M. and Ardeshir, A. and Vasheghani, H. and Jalilsani, F.}, title = {A novel Approach for Water Quality Management in Water Distribution Systems by Multi-objective Booster Chlorination}, abstract ={Compared to conventional chlorination methods which apply chlorine at water treatment plant, booster chlorination has almost solved the problems of high dosages of chlorine residuals near water sources and lack of chlorine residuals in the remote points of a water distribution system (WDS). However, control of trihalomethane (THM) formation as a potentially carcinogenic disinfection by-product (DBP) within a WDS has still remained as a water quality problem. This paper presents a two-phase approach of multi-objective booster disinfection in which both chlorine residuals and THM formation are concurrently optimized in a WDS. In the first phase, a booster disinfection system is formulated as a multi-objective optimization problem in which the location of booster stations is determined. The objectives are defined as to maximize the volumetric discharge with appropriate levels of disinfectant residuals throughout all demand nodes and to minimize the total mass of disinfectant applied with a specified number of booster stations. The most frequently selected locations for installing booster disinfection stations are selected for the second phase, in which another two-objective optimization problem is defined. The objectives in the second problem are to minimize the volumetric discharge avoiding THM maximum levels and to maximize the volumetric discharge with standard levels of disinfectant residuals. For each point on the resulted trade-off curve between the water quality objectives optimal scheduling of chlorination injected at each booster station is obtained. Both optimization problems used NSGA-II algorithm as a multi-objective genetic algorithm, coupled with EPANET as a hydraulic simulation model. The optimization problems are tested for different numbers of booster chlorination stations in a real case WDS. As a result, this type of multi-objective optimization model can explicitly give the decision makers the optimal location and scheduling of booster disinfection systems with respect to the tradeoff between maximum safe drinking water with allowable chlorine residual levels and minimum adverse DBP levels.}, Keywords = {Optimal location, Booster chlorination, Multi-objective optimization, THM formation, Water distribution system}, volume = {10}, Number = {1}, pages = {51-60}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-543-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-543-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Alamatian, E. and Jaefarzadeh, M. R.}, title = {Evaluation of turbulence models in the simulation of oblique standing shock waves in supercritical channel flows}, abstract ={In this article, the two-dimensional depth-averaged Saint Venant equations, including the turbulence terms, are solved in a supercritical flow with oblique standing waves. The algorithm applies the finite volume Roe-TVD method with unstructured triangular cells. Three depth-averaged turbulence models, including the mixing length, k-;epsilon and algebraic stress model (ASM), are used to close the hydrodynamic equations. The supercritical flow in a channel downstream from a side-baffle in plan is then simulated, and the numerical results are compared with the data obtained from a laboratory model. The application of different models demonstrates that the consideration of turbulence models improves the results at the shock wave positions. The qualitative study of the results and error analysis indicates that the ASM offers the most desirable solutions in comparison with the other models. However, our numerical experiments show that, amongst the source term components, the negligence of turbulence terms produces the least error in the depth estimation in comparison with the removal of the bed slope or bed friction terms.}, Keywords = {Finite volume method, Mixing length model, k-ε model, Algebraic stress model, Oblique standing waves}, volume = {10}, Number = {1}, pages = {61-71}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-432-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-432-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Attarnejad, R. and Kalateh, F.}, title = {Numerical simulation of acoustic cavitation in the reservoir and effects on dynamic response of concrete dams}, abstract ={This paper describes a numerical model and its finite element implementation that used to compute the cavitation effects on seismic behavior of concrete dam and reservoir systems. The system is composed of two sub-systems, namely, the reservoir and the dam. The water is considered as bilinear compressible and inviscid and the equation of motion of fluid domain is expressed in terms of the pressure variable alone. A bilinear state equation is used to model the pressure–density relationship of a cavitated fluid. A standard displacement finite element formulation is used for the structure. The Structural damping of the dam material and the radiation damping of the water and damping from foundation soil and banks have been incorporated in the analysis. The solution of the coupled system is accomplished by solving the two sub-systems separately with the interaction effects at the damreservoir interface enforced by a developed iterative scheme. The developed method is validated by testing it against problem for which, there is existing solution and the effects of cavitation on dynamic response of Konya gravity dam and Morrow Point arch dam subjected to the first 6 s of the May 1940 El-Centro, California earthquake, is considered. Obtained results show that impact forces caused by cavitation have a small effect on the dynamic response of dam-reservoir system.}, Keywords = {Dam–reservoir interaction, Finite element method, Nonlinear analysis, Cavitation, Concrete dams}, volume = {10}, Number = {1}, pages = {72-86}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-296-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-296-en.pdf}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Kirov, B.L. and Truc, N.N.}, title = {A study on the relationship between geotechnical properties and clay mineral composition of Hanoi soft soils in saline media}, abstract ={Soft soil in Hanoi, Vietnam, is mainly originated from lacustrine and shallow-sea sediment. This is the youngest formation with around 3000 years of age. To serve the research purpose, clayey soil samples at ten areas in Hanoi and some places in the RRD are prepared. Mineral composition of soils determined by X-ray diffraction analysis shows that clay minerals are predominated by Illite, Kaolinite, Chlorite, and Montmorillonite respectively. Many previous researches indicated that in saline-saturated condition, types of cation in saline water and types of clay mineral in soil layers, as well as their predomination decide the changing process of geotechnical properties in other manner. In this paper, the initial relationship between geotechnical properties and clay mineral composition of Hanoi soft soils in saline-saturated media is established}, Keywords = {Hanoi soft soils, clay mineral, saline soils, saline media, geotechnical properties}, volume = {10}, Number = {2}, pages = {87-92}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-594-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-594-en.docx}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {MahinRoosta, R. and Alizadeh, A.}, title = {Simulation of collapse settlement in rockfill material due to saturation}, abstract ={In the first impounding of rockfill dams, additional settlements occur in upstream side in saturated rockfills due to collapse phenomenon even high rainy seasons can cause additional deformation in the dumped rockfills. Unfortunately these displacements are not taken into account in the conventional numerical models which are currently used to predict embankment dam behavior during impounding. In this paper to estimate these displacements, strain hardening-strain softening model in Flac is modified based on the laboratory tests, in which same impounding process in such dams is considered. Main feature of the model is reproduction of nonlinear behavior of rockfill material via mobilized shear strength parameters and using collapse coefficient to display induced settlement due to inundation. This mobilization of shear strength parameters associated with some functions for dilatancy behavior of rockfill are used in a finite difference code for both dry and wet condition of material. Collapse coefficient is defined as a stress dependent function to show stress release in the material owing to saturation. To demonstrate how the model works, simulation of some large scale triaxial tests of rockfill material in Gotvand embankment dam is presented and results are compared with those from laboratory tests, which are in good agreement. The technique could be used with any suitable constitutive law in other coarse-grained material to identify collapse settlements due to saturation}, Keywords = {Collapse settlement, wetting, rockfill, numerical modeling, nonlinear behavior}, volume = {10}, Number = {2}, pages = {93-99}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-521-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-521-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Eslami, A. and Veiskarami, M. and Eslami, M. M.}, title = {Study on optimized piled-raft foundations (PRF) performance with connected and non-connected piles- three case histories}, abstract ={It has been realized that the raft (mat) foundations are capable of bearing very large loads when they are assisted with a pile group. The contribution of both raft and piles to carry the surcharge loads is taken into account, considering the stiffness and strength of involved elements in the system, i.e. piles, raft and surrounding soil. The piles are usually required not to ensure the overall stability of the foundation but to act as settlement reducers. There is an alternative design in which, the piles are nonconnected from the raft to reduce the settlement, which are then known to be "settlement reducer non-connected piles" to increase the system stiffness. In this paper, two and three dimensional finite element analysis of connected and non-connected pile-raft systems are performed on three case studies including a 12-storey residential building in Iran, a 39-storey twin towers in Indonesia, and the Messeturm tower, 256m high, in Frankfurt, Germany. The analyses include the investigation of the effect of different parameters, e.g. piles spacing, embedment length, piling configuration and raft thickness to optimize the design. The role of each parameter is also investigated. The parametric study results and comparison to a few field measurements indicate that by concentrating the piles in the central area of the raft foundation the optimum design with the minimum total length of piles is achieved, which is considered as control parameter for optimum design. This can be considered as a criterion for project cost efficiency. On the other hand, non-connected piled-raft systems can significantly reduce the settlements and raft internal bending moments by increasing the subsoil stratum stiffness. Finally, the comparison indicates that simple and faster 2D analysis has almost similar results to the time consuming and complicated 3D analysis.}, Keywords = {Piled-raft foundations (PRF), Optimized design, Connected piles, Non-connected piles, Finite element analysis}, volume = {10}, Number = {2}, pages = {100-111}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-461-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-461-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Askari, F. and Totonchi, A. and Farzaneh, O.}, title = {3D stability analysis of convex slopes in plan view using lower bound linear finite element}, abstract ={Presented is a method of three-dimensional stability analysis of convex slopes in plan view based on the Lower-bound theorem of the limit analysis approach. The method’s aim is to determine the factor of safety of such slopes using numerical linear finite element and lower bound limit analysis method to produce some stability charts for three dimensional (3D) homogeneous convex slopes. Although the conventional two and three dimension limit equilibrium method (LEM) is used more often in practice for evaluating slope stability, the accuracy of the method is often questioned due to the underlying assumptions that it makes. The rigorous limit analysis results in this paper together with results of other researchers were found to bracket the slope stability number to within ±10% or better and therefore can be used to benchmark for solutions from other methods. It was found that using a two dimensional (2D) analysis to analyze a 3D problem will leads to a significant difference in the factors of safety depending on the slope geometries. Numerical 3D results of proposed algorithm are presented in the form of some dimensionless graphs which can be a convenient tool to be used by practicing engineers to estimate the initial stability for excavated or man-made slopes}, Keywords = {three-dimensional slope, slope stability, limit analysis, Lower-bound, limit equilibrium}, volume = {10}, Number = {2}, pages = {112-123}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-546-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-546-en.docx}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Jalili, J. and Jafari, M. K. and Shafiee, A. and Koseki, J. and Sato, T.}, title = {An investigation on effect of inclusions on heterogeneity of stress, excess pore pressure and strain distribution in composite soils}, abstract ={A series of tests and also numerical analyses were conducted to explore the mechanical behavior of a mixture of coarse gravelsize particles floating in a matrix of silt, sand or clay. The research is a step forward in an ongoing investigation on behavior of composite clay, which is used as the core material of some large embankment dams all over the world. After providing the reader with an overall image about behavior of such materials through the literature, the paper focuses on a predominant feature of the composite soil behavior: increase of non-deformable solid inclusions in a mixture leads to formation of heterogeneity of stress field, excess pore water pressure and strain distribution along the specimens. This paper mainly probes formation of such heterogeneity by the aid of special experiments and also numerical analyses. In addition to loading details, it is clarified through the paper that position of inclusions relative to loading direction also affects heterogeneity of stress/strain and excess pore water pressure distribution through the mixture. Despite the former, the latter redistributes with a rate proportional to material hydraulic conductivity.}, Keywords = {Composite soil, Mixed material, Heterogeneity, Torsional hollow cylinder, Cyclic triaxial, Finite element analysis}, volume = {10}, Number = {2}, pages = {124-138}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-531-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-531-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Asakereh, A. and MoghaddasTafreshi, S.N. and Ghazavi, M.}, title = {Strip footing behavior on reinforced sand with void subjected to repeated loading}, abstract ={This paper describes a series of laboratory model tests on strip footings supported on unreinforced and geogrid-reinforced sand with an inside void. The footing is subjected to a combination of static and cyclic loading. The influence of various parameters including the embedment depth of the void, the number of reinforcement layers, and the amplitude of cyclic load were studied. The results show that the footing settlement due to repeated loading increased when the void existed in the failure zone of the footing and decreased with increasing the void vertical distance from the footing bottom and with increasing the reinforcement layers beneath the footing. For a specified amplitude of repeated load, the footing settlement is comparable for reinforced sand, thicker soil layer over the void and much improved the settlement of unreinforced sand without void. In general, the results indicate that, the reinforced soil-footing system with sufficient geogride-reinforcement and void embedment depth behaves much stiffer and thus carries greater loading with lower settlement compared with unreinforced soil in the absent of void and can eliminate the adverse effect of the void on the footing behavior. The final footing settlement under repeated cyclic loading becomes about 4 times with respect to the footing settlement under static loading at the same magnitude of load applied.}, Keywords = {Repeated loads, Void, Geogrid reinforcement, Laboratory test, Strip footing, Footing settlement}, volume = {10}, Number = {2}, pages = {139-152}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-525-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-525-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Soroush, A. and Jannatiaghdam, R.}, title = {Behavior of Rockfill Materials in Triaxial Compression Testing}, abstract ={This paper studies thoroughly and deeply the results of about one hundred triaxial compression tests on thirty types of rockfill materials. The materials are categorized in accordance with their particles shape (angular / rounded) and gradation characteristics. The main tool of the study is the Hyperbolic Model developed by Duncan and Chang. The focus of the study is on the variations of deformation modulus of the materials (Ei and Et) with confining stress (;sigma3). Features of the mechanical behavior of the rockfill materials, as compared with the general behavior of soils, are highlighted through the exponent parameter (n) of the Hyperbolic Model. It is shown that high confining stresses may have adverse effects on the deformation modulus of the rockfill materials and make them softer. The particle breakage phenomenon which happens during compression and shearing is found as the main factor responsible for the above effects and, in general, responsible for controlling the behavior of the materials. For the rockfill materials of this study, two correlations for estimating the initial elasticity modulus (Ei) and the internal friction angle (;phi) in terms of particles shape, confining pressure (;sigma3), and coefficient of uniformity (Cu) are suggested.}, Keywords = {Rockfill materials, Hyperbolic model, Triaxial test, Particle breakage, Deformation modulus, Internal friction angle.}, volume = {10}, Number = {2}, pages = {153-161}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-419-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-419-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Shariatmadari, N. and Saeidijam, S.}, title = {The effect of thermal history on thermo-mechanical behavior of bentonite-sand mixture}, abstract ={Bentonite-sand mixture is one of the most important candidates for engineering buffer element in nuclear waste repositoriesso the analysis of its thermo-hydro-mechanical behavior is important for design purposes.An innovative setup of classic oedometer was used for swelling and compression study at high temperatures in this research. A fully calibration program was utilized to include high temperature effects on measurements. This research shows that the elevation of temperature from 25 to 90◦C in 1:1bentonite-sand mixture in distilled water reduces free swelling potential and strain about 20 percent. The required time for equalization of swelling is less in high temperature due to increasing in permeability. Also, the high temperature causes increasing in compressibility rate and quantity for this buffer. For detection of this effect, XRD analysis showed that an increase in temperature causes a decrease in basal spacing. So, the particles can come near to each other more than lower temperatures and the amount of absorbed water in the microstructure of the clay is smaller.The effect of thermal history on behavior of bentonitesand mixture has been showed and tried to clarify it. At similar stress-temperature states, thermal history causes different deformation in samples. The highest temperature that bentonite has been experienced, controls its behavior in the next thermal cycles.}, Keywords = {Thermo-mechanical behavior, Bentonite-sand barrier, Nuclear waste repository, Thermal history, Environmental geomechanics}, volume = {10}, Number = {2}, pages = {162-167}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-578-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-578-en.docx}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Tavazo, H. and Estekanchi, H. E. and Kaldi, P.}, title = {Endurance time method in the linear seismic analysis of shell structures}, abstract ={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}, Keywords = {Endurance time method, Shell structures, Time history analysis, Response spectrum analysis}, volume = {10}, Number = {3}, pages = {169-178}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-559-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-559-en.docx}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Sanaei, E. and Babaei, M.}, title = {Topology optimization of structures using cellular automata with constant strain triangles}, abstract ={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}, Keywords = {Cellular automaton, Structural optimization, Topology, Shape, Constant Strain triangle (CST)}, volume = {10}, Number = {3}, pages = {179-188}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-515-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-515-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Kaveh, A. and Sabzi, O.}, title = {Optimal design of reinforced concrete frames Using big bang-big crunch algorithm}, abstract ={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.}, Keywords = {Optimization, Reinforced concrete plane frame, Big Bang-Big Crunch algorithm}, volume = {10}, Number = {3}, pages = {189-200}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-572-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-572-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Abbasnia, R. and Holakoo, A.}, title = {An investigation of stress-strain behavior of FRP-confined concrete under cyclic compressive loading}, abstract ={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.}, Keywords = {Confined concrete, Stress-strain behavior, Fiber reinforced polymer, Cyclic loading}, volume = {10}, Number = {3}, pages = {201-209}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-527-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-527-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Famili, H. and KhodadadSaryazdi, M. and Parhizkar, T.}, title = {Internal curing of high strength self consolidating concrete by saturated lightweight aggregate - effects on material properties}, abstract ={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.}, Keywords = {High strength self consolidating concrete, Autogenous shrinkage, Drying shrinkage, internal curing, Saturated lightweight aggregate, Freezing-thawing resistance}, volume = {10}, Number = {3}, pages = {210-221}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-597-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-597-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Molavi-Tabrizi, A. H. and Khoshnoudian, F.}, title = {Responses of isolated building with MR Dampers and Fuzzy Logic}, abstract ={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}, Keywords = {Semi-active control, MR damper, Near-field earthquakes, Base-isolated building, Fuzzy control algorithm.}, volume = {10}, Number = {3}, pages = {222-231}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-504-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-504-en.docx}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Tasnimi, A. A. and Rezazadeh, M. A.}, title = {Experimental and numerical study of strengthened single storey brick building under torsional moment}, abstract ={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.}, Keywords = {Brick building, Numerical micro-modeling, Strengthening, Torsional behavior, Vulnerable connection}, volume = {10}, Number = {3}, pages = {232-244}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-481-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-481-en.docx}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Rofooei, F.R. and Mirjalili, M. R. and Attari, N. K. A.}, title = {Modal spectra combination method for pushover analysis of special steel moment resisting frames}, abstract ={The nonlinear static procedures (NSPs) proposed by design codes do not lead to reliable results especially for tall buildings. They generally provide inconsistent estimates of inelastic seismic demands, especially for the top floors due to their inabilities in considering the higher modes effects. In this paper, a new enhanced pushover procedure is proposed which is based on the envelope of the structural responses resulting from two separate pushover analyses as a combination rule. Also, the suggested pushover analyses are performed using a newly proposed modal load pattern, i.e., the Modal Spectra Combination (MSC), and the ASCE41-06 required first mode load pattern. The MSC load pattern is consisted of a number of mode shapes combined with appropriate weighting factors that depend on their modal participation factors, modal frequencies and design spectral values. A number of 2-D steel moment resisting frame models with different number of stories are used to investigate the efficiency of the proposed method. The inter-story drifts and the maximum plastic beam moment and curvature responses are used as a measure to compare the results obtained from the nonlinear time-history analyses (NL-THA) and some other NSPs. The results obtained through rigorous nonlinear dynamic analyses show that the application of the proposed method leads to acceptable results for steel MRF systems in comparison to other available enhanced NSPs. The OpenSees program is used for numerical analysis.}, Keywords = {Nonlinear static analysis, Pushover analysis, Lateral load pattern, Nonlinear dynamic analysis}, volume = {10}, Number = {4}, pages = {245-252}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-573-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-573-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Arabzadeh, A. and Aghayari, R. and Rahai, A. R.}, title = {A new model for predicting the effective strength in reinforced concrete bottle-shaped struts}, abstract ={Strut-and-Tie Model (STM) can be used to model the flow of compression within a concrete strut. Concrete struts are formed in various shapes such as prismatic or bottle-shaped. In order to study the behavior of concrete struts, a series of simple tests were performed. Eighteen reinforced concrete isolated struts with compressive strength of 65 MPa were tested up failure under point loading in the plane of specimens. The tested specimens were reinforced by various reinforcement layouts. The behavior of tested beams was investigated. Observations were made on transverse displacement, primary cracking and ultimate failure load and distribution of strain on the face of tested panels. Based on these observations, the geometry of the concrete struts was examined. a new model to analysis of concrete struts was proposed based on modified compression field theory (MCFT). A database of 44 tested specimens was compiled to evaluate the proposed model. The results indicate that using the ACI and CSA codes expressions regarding the amount of minimum required reinforcement in a strut produces conservative but erratic results when compared with the test data. Conversely, the new proposed model presents a more accurate prediction for the strength of 44 tested struts.}, Keywords = {Strut-and-tie, Transverse reinforcement, Strut, Efficiency factor}, volume = {10}, Number = {4}, pages = {253-262}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-479-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-479-en.docx}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Maghsoudi, A. A. and AkbarzadehBengar, H.}, title = {Ultimate axial load and moment interaction diagrams for prestressed HPC thin-walled short columns}, abstract ={In order to lighten the prestressed concrete solid members, nowadays, it is possible to make use of the advantage of HPC (fc;#39>60 MPa) as well as replacing the solid section with a PSC thin-walled section for certain members such as circular and box columns. Using the strength theory of ACI, a numerical procedure along with a computer program was developed for the analysis of such sections subjected to axial compression or tension load and bending moments. The program solves for all possible variables such as, concrete compressive strength (fc;#39= 60-100 MPa), type of prestressed steel, concrete cover, ratio of wall thickness to the section dimensions and the PS steel arrangements to satisfy the given loading cases, thus leading to an optimal cost solution. However, since the cross section is thin-walled circular or box and the PS steel is located at discrete points along the periphery of a circle or rectangle, the equations of equilibrium are complex for hand computations (especially for circular section) but suitable for computer program. So, by use of MATLAB software the interaction diagrams were also drawn for the analysis of such sections for all mentioned variables. The use of prestressed thin-walled column diagrams is a safe and easy tool for the analysis of such columns. Finally, the accuracy of the proposed method is demonstrated by comparing its results to those of the available experimental values and is indicate that the proposed method predict very well the capacity of prestressed thin-walled column.}, Keywords = {Analysis, Prestressed HPC, Thin-walled columns, Interaction diagrams}, volume = {10}, Number = {4}, pages = {263-273}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-358-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-358-en.pdf}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Ahmadii, R. and Ghoddousi, P. and Sharifi, M.}, title = {A simple solution for prediction of steel fiber reinforcd concrete behavior under flexure}, abstract ={The main objective of this study is to drive a simple solution for prediction of steel fiber reinforced concrete (SFRC) behavior under four point bending test (FPBT). In this model all the force components at the beam section (before and after cracking) are formulated by applying these assumptions: a bilinear elastic-perfectly plastic stress-strain response for concrete behavior in compression, a linear response for the un-cracked tension region in a concrete constitutive model, and an exponential relationship for stress-crack opening in the crack region which requires two parameters.Then the moment capacity of the critical cracked section is calculated by applying these assumptions and satisfying equilibrium lawat critical cracked section. After that, parametric studies have been done on the behavior of SFRC to assess the sensitively of model. Finally the proposed model has been validated with some existing experimental tests.The result shows that the proposed solution is able to estimate the behavior of SFRC under FPBT with simplicity and proper accuracy.}, Keywords = {Steel fiber reinforced concrete, Flexure, Stress-crack opening, Four point bending test (FPBT)}, volume = {10}, Number = {4}, pages = {274-279}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-304-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-304-en.pdf}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Beheshti-Aval, B.}, title = {Strength evaluation of concrete-filled steel tubes subjected to axial-flexural loading by ACI and AISC-LRFD codes along with three dimensional nonlinear analysis}, abstract ={A comparison between design codes i.e. ACI and AISC-LRFD in evaluation of flexural strength of concrete filled steel tubular columns (CFTs) is examined. For this purpose an analytical study on the response of CFTs under axial-flexural loading is carried using three-dimensional finite elements with elasto-plastic model for concrete with cracking and crushing capability and elastoplastic kinematic hardening model for steel. The accuracy of the model is verified against previous test results. The nonlinear modeling of CFT columns shows that the minimum thickness that recommended by ACI and AISC-LRFD to prevent local buckling before the steel shell yielding for CFT columns could be decreased. The comparison of analytical results and codes indicates that the accuracy of ACI method in estimation of axial-flexural strength of CFT columns is more appropriate than AISC-LRFD. The ACI lateral strength of CFTs is located on upper bond of the AISC-LRFD’s provisions. AISC-LRFD estimates the lateral strength conservatively but ACI in some ranges such as in short columns or under high axial load levels computes lateral strength in nonconservative manner. Supplementary provisions for post local buckling strength of CFT columns should be incorporated in high seismic region. This effect would be pronounced for column with high aspect ratio and short columns.}, Keywords = {Code, Concrete, Steel, Finite element modeling, Composite member, Confinement}, volume = {10}, Number = {4}, pages = {280-290}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-535-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-535-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Kabir, M. Z. and Hojatkashani, A.}, title = {Experimental examination of CFRP strengthened RC beams under high cycle fatigue loading}, abstract ={The aim of current study is to investigate the effect of Carbon Fiber Reinforced Polymer (CFRP) composites on the fatigue response of reinforced concrete beams. 6 reinforced concrete (RC) beams from which 3 were retrofitted with CFRP sheets, were prepared and subjected to fatigue load cycles. To predict and trace the failure occurrence and its growth, a small notch was induced at the middle span in bottom surface of all RC specimens. At the certain points, strains in concrete and CFRP were measured in each cycle. The upper limit of applied load was considered at the level of design service load of bridges. In addition, strain measurements facilitated to the calculation of interfacial shear stresses between concrete substrate and the CFRP layer. The variation of such stresses through load cycles has been presented and discussed. Also, a discussion on possibility of the local debonding phenomenon resulted from such interfacial stresses was presented. Load–deflection curves, strain responses and propagation of tensile cracks provided an insight on the performance of the CFRP strengthened beams subjected to different cycles of fatigue loading. Variation of load-deflection curves through fatigue load cycles depicted stiffness degradation which was discussed in the research.}, Keywords = {Carbon fiber reinforced polymer, Fatigue, Interfacial shear stresses, Tensile cracks}, volume = {10}, Number = {4}, pages = {291-300}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-665-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-665-en.docx}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Kaveh, A. and Farahani, M. and Shojaei, N.}, title = {Optimal design of barrel vaults using charged search system}, abstract ={Barrel vaults are attractive space structures that cover large area without intermediate supports. In this paper, the charged search system (CSS) optimization algorithm is employed for optimal design of barrel vaults. This method utilizes the governing laws of Coulomb and Gauss from electrostatics and the Newtonian law of mechanics. The results demonstrate the efficiency of the discrete CSS algorithm compared to other meta-heuristic algorithms.}, Keywords = {Heuristic optimization algorithm, Charged system search, Optimal design of barrel vaults}, volume = {10}, Number = {4}, pages = {301-308}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-612-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-612-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Tarighat, A.}, title = {Stochastic modeling and calibration of chloride content profile in concrete based on limited available data}, abstract ={Chloride ion ingress in concrete is the main reason of concrete corrosion. In real world both uncertainty and stochasticity are main attributes of almost all measurements including testing and modeling of chloride content profile in concrete. Regarding these facts new models should be able to represent at least some of the uncertainties in the predictions. In this paper after inspiration from classical physics related to diffusion and random walk concepts a stochastic partial differential equation (SPDE) of diffusion is introduced to show a more realistic modeling/calibration scheme for construction of stochastic chloride content profile in concrete. Diffusion SPDE provides a consistent quantitative way of relating uncertainty in inputs to uncertainty in outputs. Although it is possible to run sensitivity analysis to get some statistical results from deterministic models but the nature of diffusion is inherently stochastic. Brownian motion process (Wiener process) is used in SPDE to simulate the random nature of the diffusion in heterogeneous media or random fields like concrete. The proposed method can be used to calibrate/model the chloride ion profile in concrete by only some limited data for a given depth. Then the stochastic chloride ion diffusion can be simulated by langevin equation. Results of the method are compared with data from some references and all show good agreements.}, Keywords = {Concrete corrosion, Markov process, Stochastic partial differential equation (SPDE), Langevin equation}, volume = {10}, Number = {4}, pages = {309-316}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-621-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-621-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Yitmen, I.}, title = {Organizational learning and performance improvement in civil engineering design firms}, abstract ={Learning rapidly and competently has become a pre-eminent strategy for improving organizational performance in the new knowledge era. Improving dynamic learning capability is an exclusive strategy for corporate success in construction industry. Thus engineering design firms should implement OL to accomplish a state of readiness for change and develop a competence to respond and identify future business potentials. This study aims to analyze the relationship between organizational learning (OL) and performance improvement (PI) in civil engineering design firms of Turkish construction industry. OL structure in engineering design firms incorporates five constructs: organizational environment, strategy development and implementation, supportive leadership, leveraging knowledge, and learning capability. The empirical data was collected through a questionnaire survey conducted to engineering design firms registered to the Turkish Chamber of Civil Engineers. The hypothesized model relationships were tested using Structural Equation Modeling (SEM). The results show that each of the variables has a different role and significant positive impact on the OL process and organizational PI. The variables “Supportive leadership” and “Learning capability” proved to be strongly significant and positively related to organizational performance in engineering design firms. In engineering design firms, supportive leadership is needed in order to establish a participative cultural environment that helps design a new form of organization which emphasizes learning, flexibility, and rapid response. Learning capability is the potential to explore and exploit knowledge through learning flows that make possible the development, evolution and use of knowledge stocks enacting engineering design firms and their members to add value to the design business.}, Keywords = {Organizational learning, Performance improvement, Civil engineering design firms, Construction industry}, volume = {10}, Number = {4}, pages = {317-327}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-485-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-485-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Karamouz, M. and Fallahi, M. and Nazif, S. and RahimiFarahani, M.}, title = {Long Lead Runoff Simulation Using Data Driven Models}, abstract ={Runoff simulation is a vital issue in water resource planning and management. Various models with different levels of accuracy and precision are developed for this purpose considering various prediction time scales. In this paper, two models of IHACRES (Identification of unit Hydrographs And Component flows from Rainfall, Evaporation and Streamflow data) and ANN (Artificial Neural Network) models are developed and compared for long term runoff simulation in the south eastern part of Iran. These models have been utilized to simulate5-month runoff in the wet period of December-April. In IHACRES application, first the rainfall is predicted using climatic signals and then transformed to runoff. For this purpose, the daily precipitation is downscaled by two models of SDSM (Statistical Downscaling Model) and LARS-WG (Long Ashton Research Station-Weather Generator). The best results of these models are selected as IHACRES model input for simulating of runoff. In application of the ANN model, effective large scale signals of SLP(Sea Level Pressure), SST(Sea Surface Temperature), DSLP and runoff are considered as model inputs for the study region. The performances of the considered models in real time planning of water resources is evaluated by comparing simulated runoff with observed data and through SWSI(Surface Water Scarcity Index) drought index calculation. According to the results, the IHACRES model outperformed ANN in simulating runoff in the study area, and its results are more likely to be comparable with the observed values and therefore, could be employed with more certainty.}, Keywords = {Downscaling, Long term runoff, Simulation, ANN, Large scale climate signals, IHACRES}, volume = {10}, Number = {4}, pages = {328-336}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-414-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-414-en.doc}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} } @article{ author = {Kavianpour, M. R. and Rajabi, E.}, title = {Optimum algorithm for channel flow analysis in direct numerical simulation method}, abstract ={The objective of this work is to perform a direct numerical simulation of turbulent channel flow where all essential scales of motion are resolved due to variable time-stepping algorithm in various time advancement method and different discritized form of convection term. A pseudo spectral method (Fourier series in stream-wise and span-wise directions and Chebychev polynomial expansion in normal direction) is employed for the spatial derivatives. The time advancement is carried out by different semiimplicit and splitting schemes. Also Alternating and Linearized forms are added to four commonly used forms of the convective term, referred to as divergence, Convection, skew-symmetric, and rotational. Spectral method based on the primitive variable formulation is used in Cartesian coordinates with two periodic and one non-periodic boundary condition in three dimensional directions ;Omega=[0,4;pi]×[-1,1]×[0,2;pi]. The friction Reynolds number for channel flow is set to be Re;tau=175 and the computational grids of 128×65×128 are used in the x, y and z directions, respectively. The comparison is made between turbulent quantities such as the turbulent statistics, wall shear velocity, standard deviation of u and total normalized energy of instantaneous velocities in different time-discretization methods and different forms of nonlinear term. The present results show that third-order timediscretizations forward Euler for explicit terms and backward Euler for implicit terms can minimize the computational cost of integration by maximizing the time step, while keeping the CFL number near a threshold in time-discretization schemes. Also, the de-aliased results of turbulence statistics do indicate that different expressions of nonlinear terms have minor discrepancy in pseudo spectral method. The results show that the most desirable approach is a combination of variable time stepping third order backward difference algorithm and rotational form, which provides reduced cost and further accuracy improvements.}, Keywords = {Channel flow, Pseudo spectral method, DNS, Time-discretization schemes, Nonlinear term forms}, volume = {10}, Number = {4}, pages = {337-344}, publisher = {}, title_fa = {}, abstract_fa ={}, keywords_fa = {}, url = {http://ijce.iust.ac.ir/article-1-568-en.html}, eprint = {http://ijce.iust.ac.ir/article-1-568-en.docx}, journal = {International Journal of Civil Engineering}, issn = {1735-0522}, eissn = {2283-3874}, year = {2012} }