University of TehranCivil Engineering Infrastructures Journal2322-209347120140601Automatic Calibration of HEC-HMS Model Using Multi-Objective Fuzzy Optimal Models1125031210.7508/ceij.2014.01.001ENB.KamaliPhD. Student, College of Civil and Environmental Engineering, Amirkabir University of Technology, P.O. Box: 15875-4413, Tehran, Iran.S.J.MousaviAssociate Professor, College of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran. P.O. Box: 15875-4413, Tehran, Iran.Journal Article20110914Estimation of parameters of a hydrologic model is undertaken using a procedure called “calibration” in order to obtain predictions as close as possible to observed values. This study aimed to use the particle swarm optimization (PSO) algorithm for automatic calibration of the HEC-HMS hydrologic model, which includes a library of different event-based models for simulating the rainfall-runoff process. Since a flood hydrograph has different characteristics such as time to peak, peak discharge and total runoff volume, the calibration process is addressed using a single-objective or multi-objective optimization model. In this context, the fuzzy set theory can be used to combine different objective functions and convert the multi-objective model to a single-objective one. In this research, the Tamar basin, a sub-basin of the Golestan-Dam Basin in north of Iran, was selected as the case study with four reliable measured flood events. The first three events were used for calibration and the fourth one for verification. As most of the models built in the HEC-HMS software were event-based, the concept of recalibration of parameters related to a basin initial condition was also introduced. The comparison of results obtained from the single and multi-objective scenarios showed the efficiency of the proposed HMS-PSO simulation-optimization approach in the multi-objective calibration of event-based hydrologic models.https://ceij.ut.ac.ir/article_50312_ad25e6288159978168e19090cb55bb03.pdfUniversity of TehranCivil Engineering Infrastructures Journal2322-209347120140601A Method of Function Space for Vertical Impedance Function of a Circular Rigid Foundation on a Transversely Isotropic Ground13275031310.7508/ceij.2014.01.002ENMortezaEskandari-GhadiUniversity of Tehran, Collage of Engineering, Dept. of Engineering ScienceAliHassanpour CharmhiniUniversity of Science and technology of MazandaranAzizollahArdeshir-BehrestaghiMazandaran University of Science and TechnologyJournal Article20111227This paper is concerned with investigation of vertical impedance function of a surface rigid circular foundation resting on a semi-infinite transversely isotropic alluvium. To this end, the equations of motion in cylindrical coordinate system, which because of axissymmetry are two coupled equations, are converted into one partial differential equation using a method of potential function. The governing partial differential equation for the potential function is solved via implementing Hankel integral transforms in radial direction. The vertical and radial components of displacement vector are determined with the use of transformed displacement-potential function relationships. The mixed boundary conditions at the surface are satisfied by specifying the traction between the rigid foundation and the underneath alluvium in a special function space introduced in this paper, where the vertical displacements are forced to satisfy the rigid boundary condition. Through exercising these restraints, the normal traction and then the vertical impedance function are obtained. The results are then compared with the existing results in the literature for the simpler case of isotropic half-space, which shows an excellent agreement. Eventually, the impedance functions are presented in terms of dimensionless frequency for different materials. The method presented here may be used to obtain the impedance function in any other direction as well as in buried footing in layered media.https://ceij.ut.ac.ir/article_50313_f5e3357aeb8b1e1f7fb92b865d79e14f.pdfUniversity of TehranCivil Engineering Infrastructures Journal2322-209347120140601Efficiency of Neural Networks for Estimating the Patch Load Resistance of Plate Girders with a Focus on Uncertainties in Material and Geometrical Properties29425031410.7508/ceij.2014.01.003ENFarzadShahabianAssociate Professor, Civil Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran.Sidi MohammedElachachiProfessor, University of Bordeaux1, I2M-GCE, 33405 Talence, France.DenysBreysseProfessor, University of Bordeaux1, I2M-GCE, 33405 Talence, France.Journal Article20120303In this paper, a sensitivity analysis of artificial neural networks (NNs) is presented and employed for estimating the patch load resistance of plate girders subjected to patch loading. To evaluate the accuracy of the proposed NN model, the results are compared with the previously proposed empirical models, so that we can estimate the resistance of plate girders subjected to patch loading. The empirical models are calibrated, for improving the formulae, with experimental data set which was collected from the corresponding literature. NNs models are later trained and validated through using the existing experimental data. In this process several NNs architectures are taken into account. A set of good NNs models are selected and then analyzed regarding their robustness when confronted with the test data set and regarding their ability to reproduce the effect of uncertainty on the data. A sensitivity analysis is conducted herein in order to investigate the effect of variability in material and geometrical properties of plate girders. Thereafter, several estimates measuring the efficiency and the quality of the NN model and the calibrated models are obtained and discussed.https://ceij.ut.ac.ir/article_50314_afd2c195149544066539f3c4860e2dc8.pdfUniversity of TehranCivil Engineering Infrastructures Journal2322-209347120140601Prioritizing Roads Safety Based on the Quasi-Induced Exposure Method and Utilization of the Analytical Hierarchy Process43584086810.7508/ceij.2014.01.004ENSajadRezaeiMSc., Faculty of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.HamedNafarMSc., Faculty of Civil Engineering, University Putra, Malaysia.HamidBehbahaniProfessor, Faculty of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.Journal Article20120605Safety analysis of the roads through the accident rates which is one of the widely used tools has been resulted from the direct exposure method which is based on the ratio of the vehicle-kilometers traveled and vehicle-travel time. However, due to some fundamental flaws in its theories and difficulties in gaining access to the data required such as traffic volume, distance and duration of the trip, and various problems in determining the exposure in a specific time, place, and individual categories, there is a need for an algorithm for prioritizing the road safety so that with a new exposure method, the problems of the previous approaches would be resolved. In this way, an efficient application may lead to have more realistic comparisons and the new method would be applicable to a wider range of time, place, and individual categories. Therefore, an algorithm was introduced to prioritize the safety of roads using the quasi-induced exposure method and utilizing the analytical hierarchy process. For this research, 11 provinces of Iran were chosen as case study locations. A rural accidents database was created for these provinces, the validity of quasi-induced exposure method for Iran’s accidents database was explored, and the involvement ratio for different characteristics of the drivers and the vehicles was measured. Results showed that the quasi-induced exposure method was valid in determining the real exposure in the provinces under study. Results also showed a significant difference in the prioritization based on the new and traditional approaches. This difference mostly would stem from the perspective of the quasi-induced exposure method in determining the exposure, opinion of experts, and the quantity of accidents data. Overall, the results for this research showed that prioritization based on the new approach is more comprehensive and reliable compared to the prioritization in the traditional approach which is dependent on various parameters including the driver-vehicle characteristics.https://ceij.ut.ac.ir/article_40868_969dc650c4f20149d7dfbc9ce130119b.pdfUniversity of TehranCivil Engineering Infrastructures Journal2322-209347120140601Experimental Study of the Performance of Floating Breakwaters with Heave Motion59705031510.7508/ceij.2014.01.005ENMortezaKolahdoozanAmirkabir University of Technology (Tehran Polytechnic)Mohammad JavadAlizadehAmirkabir University of TechnologyAhmadTahershamsiAmirkabir University of TechnologyA.AbdolaliPh.D. Candidate, Department of Civil and Environmental Engineering, University of Roma Tre.Journal Article20120723Nowadays, the application of floating breakwaters in small or recreational harbors has found more popularity. These types of breakwaters are more flexible in terms of design, configuration and especially installation compared with fixed breakwaters. In the current study, the performance of floating breakwater (FBs) under regular waves was studied using the physical modeling method. For the modeling practice, a wave flume with a flap-type wave generator and progressive wave absorber was designed, constructed and used in order to investigate the performance of FBs. In this regard, a number of geometrical and hydrodynamic parameters were chosen including the degree of freedom, width variation, FB shapes (pontoon, T and types) and draft depth. In each scenario the water level variation was measured in three points along the flume. Based on the measured water levels transmission, reflection and energy dissipation coefficients were obtained. The effect of each parameter on the performance of FBs was investigated and the best configuration was proposed for further studies. According to the collected experimental data, the mathematical descriptions for calculating the transmission coefficient were also proposed.https://ceij.ut.ac.ir/article_50315_93a5f83fa9ef66a5e0145b5afc7fb251.pdfUniversity of TehranCivil Engineering Infrastructures Journal2322-209347120140601Numerical Study of Progressive Collapse in Intermediate Moment Resisting Reinforced Concrete Frame Due to Column Removal71884087910.7508/ceij.2014.01.006ENSeyed MehdiZahraiAssociate Professor, Center of Excellence for Engineering and Management of Civil Infrastructures, School of Civil Engineering, College of Engineering, University of Tehran, P.O.Box: 11155-4563, Tehran, Iran.0000-0003-2759-2424AlirezaEzoddinPh.D. Student, Faculty of Civil Engineering, University of Semnan, Semnan, Iran.Journal Article20120901Progressive collapse is a chain reaction of failures propagating throughout a portion of the structure disproportionate to the original local failure occurring when a sudden loss of a critical load‐bearing element initiates a structural element failure, eventually resulting in partial or full collapse of the structure. Both General Services Administration (GSA) and United States Department of Defense (DoD) guidelines incorporate a threat-independent approach to progressive collapse analysis. Therefore, there is an international trend for updating structural design requirements to explicitly design structures to resist progressive collapse. This paper presents simple analytical approach for evaluating progressive collapse potential of typical concrete buildings, comparing four methods for progressive collapse analysis by studying 5 and 10-story intermediate moment-resistant reinforced concrete frame buildings, employing increasingly more complex analytical procedures: linear-elastic static, nonlinear static, linear-elastic dynamic, and nonlinear dynamic methodologies. Each procedure is thoroughly investigated and its common shortcomings are identified. The evaluation uses current GSA progressive collapse guidelines and can be used in routine design by practicing engineers. These analyses for three column-removal conditions are performed to evaluate the behavior of RC buildings under progressive collapse. Based on obtained findings, dynamic analysis procedures -easy to perform for progressive collapse determination- yielded more accurate results.https://ceij.ut.ac.ir/article_40879_739d8f48aede13808bee3ff0d5cb6ece.pdfUniversity of TehranCivil Engineering Infrastructures Journal2322-209347120140601Bearing Capacity of Strip Footings near Slopes Using Lower Bound Limit Analysis891094087810.7508/ceij.2014.01.007ENJavadMofidi RouchiM.Sc student, School of Civil Engineering, University College of Engineering, University of Tehran,
Tehran, Iran.OrangFarzanehAssistant Professor, School of Civil Engineering, University College of Engineering, University of Tehran,
Tehran, Iran.FaradjollahAskariAssistant Professor, International Institute of Earthquake Engineering and Seismology, Tehran, Iran.Journal Article20121014Stability of foundations near slopes is one of the important and complicated problems in geotechnical engineering, which has been investigated by various methods such as limit equilibrium, limit analysis, slip-line, finite element and discrete element. The complexity of this problem is resulted from the combination of two probable failures: foundation failure and overall slope failure. The current paper describes a lower bound solution for estimation of bearing capacity of strip footings near slopes. The solution is based on the finite element formulation and linear programming technique, which lead to a collapse load throughout a statically admissible stress field. Three-nodded triangular stress elements are used for meshing the domain of the problem, and stress discontinuities occur at common edges of adjacent elements. The Mohr-Coulomb yield function and an associated flow rule are adopted for the soil behavior. In this paper, the average limit pressure of strip footings, which are adjacent to slopes, is considered as a function of dimensionless parameters affecting the stability of the footing-on-slope system. These parameters, particularly the friction angle of the soil, are investigated separately and relevant charts are presented consequently. The results are compared to some other solutions that are available in the literature in order to verify the suitability of the methodology used in this research.https://ceij.ut.ac.ir/article_40878_c5f24e7ec84bd4fd09d443360d5b4b42.pdfUniversity of TehranCivil Engineering Infrastructures Journal2322-209347120140601Taguchi Modeling for Techno-Economical Evaluation of Cr+6 Removal by Electrocoagulation Process With the Aid of Two Coagulants1111234087710.7508/ceij.2014.01.008ENSepidehSadeghiAmirkabir Uni. of Tech.Seyed Mohammad RezaAlavi MoghaddamAmirkabir University of TechnologyMokhtarAramiAmirkabir Uni. of Tech.Journal Article20120923The research aimed to apply the Taguchi method for techno-economical evaluation of Cr<sup>+6</sup> removal using the electro-coagulation process with the aid of two different coagulants (FeCl<sub>3</sub> and PAC). Taguchi orthogonal array L27 (3<sup>13</sup>) was applied for analyzing the effect of four variables including initial pH, reaction time, current density and coagulant types in an attempt to improve the chromium removal efficiency. Based on the signal-to-noise ratio (S/N) and the analysis of variance (ANOVA), the results indicated that the reaction time was the most important variable on the hexavalent chromium removal efficiency. However, the current density, reaction time and coagulant types significantly influenced the operating costs. The optimum conditions for the mentioned variables were found to be an initial pH of 7, a reaction time of 60 min, a current density of 12.5 mA/cm<sup>2 </sup>and FeCl<sub>3</sub> as a coagulant. Due to the interaction between the initial pH and coagulant type at pH 7, PAC also considered as a coagulant in this experiment. Under the mentioned conditions, the removal efficiencies of 92% and 95% were achieved using the chromium removal process by FeCl<sub>3</sub> and PAC, respectively.https://ceij.ut.ac.ir/article_40877_5f4bd27b380030ce5460eb06fadec12f.pdfUniversity of TehranCivil Engineering Infrastructures Journal2322-209347120140601Rocking Rotation of a Rigid Disk Embedded in a Transversely Isotropic Half-Space1251384087510.7508/ceij.2014.01.009ENSeyed FarzadAhmadiDepartment of Civil Engineering, School of Science and Engineering, Sharif University
of Technology, International Campus, Kish Island, P.O. Box 79417-76655, Kish, IranMortezaEskandariDepartment of Civil Engineering, School of Science and Engineering, Sharif University
of Technology, International Campus, Kish Island, P.O. Box 79417-76655, Kish, IranJournal Article20121026The asymmetric problem of rocking rotation of a circular rigid disk embedded in a finite depth of a transversely isotropic half-space is analytically addressed. The rigid disk is assumed to be in frictionless contact with the elastic half-space. By virtue of appropriate Green's functions, the mixed boundary value problem is written as a dual integral equation. Employing further mathematical techniques, the integral equation is reduced to a well-known Fredholm integral equation of the second kind. The results related to the contact stress distribution across the disk region and the equivalent rocking stiffness of the system are expressed in terms of the solution of the obtained Fredholm integral equation. When the rigid disk is located on the surface or at the remote boundary, the exact closed-form solutions are presented. For verification purposes, the limiting case of an isotropic half-space is considered and the results are verified with those available in the literature. The jump behavior in the results at the edge of the rigid disk for the case of an infinitesimal embedment is highlighted analytically for the first time. Selected numerical results are depicted for the contact stress distribution across the disk region, rocking stiffness of the system, normal stress, and displacement components along the radial axis. Moreover, effects of anisotropy on the rocking stiffness factor are discussed in detail.https://ceij.ut.ac.ir/article_40875_f30c6b2c0c0543cdf1390eebcb0d0a84.pdfUniversity of TehranCivil Engineering Infrastructures Journal2322-209347120140601Medium Term Hydroelectric Production Planning - A Multistage Stochastic Optimization Model1391524087410.7508/ceij.2014.01.010ENBITAANALUIPhD Candidate, Institute of Statistics and Operations Research (ISOR), University of Vienna, Vienna, Austria.RaimundKovacevicPhD, Institute of Statistics and Operations Research (ISOR), University of Vienna, Vienna,Austria.Journal Article20121114Multistage stochastic programming is a key technology for making decisions over time in an uncertain environment. One of the promising areas in which this technology is implementable, is medium term planning of electricity production and trading where decision makers are typically faced with uncertain parameters (such as future demands and market prices) that can be described by stochastic processes in discrete time. We apply this methodology to hydrosystem operation assuming random electricity prices and random inflows to the reservoir system. After describing the multistage stochastic model a simple case study is presented. In particular we use the model for pricing an electricity delivery contract in the framework of indifference pricing.https://ceij.ut.ac.ir/article_40874_9e5e3d107c65f65d84f326fc323f747b.pdf