واترلو، واترلو، کانادا
مهندسی عمران- سازه
دانشگاه صنعتی شریف، تهران، ایران
راه و ساختمان
پلیتکنیک تهران، تهران، ایران
در سال 1335 در زنجان متولد شدم. دوران دبستان و دبیرستان را در تهران گذراندم. در سال 1353 همزمان در دانشگاه پلی تکنیک تهران (امیرکبیر فعلی) در رشته راه و ساختمان و در دانشگاه شریف در رشته سازه پذیرفته شدم. راه و ساختمان را انتخاب کردم. در سال 1364 وارد دوره کارشناسی ارشد سازه در دانشگاه شریف شدم. پایان نامه را زیر نظر دکتر فرشی در زمینه تحلیل مجدد سازه ها انجام دادم. در سال 1367 فارغ التحصیل شدم. در سال 1368 به دانشگاه واترلو (بهترین دانشگاه مهندسی کانادا) رفتم و در زمینه بهینه سازی قابهای بتن مسلح تحصیل کردم. در سال 1993 (1372) فارغ التحصیل شدم و از همان سال در دانشگاه تربیت مدرس مشغول کار شدم. در حالی که عضو بخش عمران دانشکده فنی و مهندسی بودم به معاونت عمرانی دانشگاه برگزیده شدم. در سال 1376 ریاست دانشگاه زنجان بر عهده بنده گذاشته شد. در سال 1380 به دانشگاه تربیت مدرس برگشتم. چندین دوره دو ساله مدیر گروه سازه بودم. یک دوره معاون آموزشی دانشکده فنی و مهندسی شدم. و اکنون مدیر گروه سازه و زلزله دانشکده عمران و محیط زیست هستم. بنده ازدواج کرده و فعلاً ساکن تهران هستم. همچنین دارای دو فرزند پسر و یک نوه دختر می باشم.
In this study, the method of inscribed hyperspheres (IHS) is presented and applied for the optimal design of 2-D steel moment frame structures. The weight of the structures, which is a function of the design variables (cross-sectional areas), is optimized subject to stress, displacement, size limits, and the variables’ linkage constraints. The IHS approach is employed to find the acceptable centers. The basic idea of this method is to inscribe the largest possible sphere in a closed space that has been created by the objective function and linearized constraints in each step. The obtained results were presented in discrete and continuous variables and compared to the results reported in the literature. This comparison showed the efficienc
Static nonlinear analysis of frames and plane stress/strain structures via mathematical programming algorithms has been addressed by many researchers. It has been shown that the method of Dissipated Energy Maximization (DEM) is an efficient algorithm for nonlinear static analysis. This study extends the application of DEM method to the nonlinear dynamic analysis of frames considering bending moment-axial force interaction. The nonlinear static analysis algorithm that is the basis of nonlinear dynamic analysis, and corresponding assumptions including linear-kinematics, lumped-plasticity, piecewise-linear yield function, and the associated flow rule are briefly explained. The dynamic analysis that is carried out by Duhamel integral method is
Several self-centering systems have been developed and tested so far, and all of them confront problems. Several stress like relaxation, elongation capacity and high post-yield stiffness are some of the problems, which should be addressed. The aim of this study is to find a solution to these problems. To this end, a new pre-compressed self-centering system has been proposed, tested and studied. Pre-compressed springs have been used to provide the required restoring force. Since the spring is under pressure and it has a high elastic capacity, the problem related to limited elongation capacity no longer exists. The experimental result indicates that the proposed self-centering brace has complete self-centering behaviour and low postyield stif
1. Introduction: In this research a neural network algorithm is used to process information of numerous nonlinear dynamicanalyses data so that the damage induced by an earthquake (similar to earthquakes of this study) in a structure can beobtained in an acceptable range of accuracy by spending much less time than the computation time for actualnonlinear analysis of the structure …..
Generally, beams are designed to withstand bending and shear stresses, in practice, as well as for local yielding or instability under load and lateral torsional buckling. Another type of instability has been observed as a mode of failure in steel beams under some circumferences, referred to as “web sidesway buckling” or\tension flange instability" in previous work and steel design codes, and is related to the lateral movement of tension flanges and tension zones of the web with considerable reduction in the load bearing of the beam. Experimental and numerical work has been conducted for web sidesway buckling, mostly based on simple analytical, experimental or numerical models that provide a conservative estimate of the load capacity of
Abstract-----------------------------Many bridge engineers assume that vertical ground motions during seismic events are unimportant. Current seismic design requirements do not attempt to account for vertical motion effects. Of earthquakes. However the Study on the Accelerometers of the past earthquake indicates that the vertical acceleration can reach values comparable to (and sometimes even higher than) the horizontal accelerations.
Magnetorheological (MR) dampers have the advantage of being tuned by low voltages. This has attracted many researchers to develop semi-active control of structures in theory and practice. Most of the control strategies first obtain the desired forces of dampers without taking their dynamics into consideration and then determine the input voltages according to those forces. As a result, these strategies may face situations where the desired forces cannot be produced by the dampers. In this article, by integrating the equations of the dynamics of MR dampers and the structural motion, and solving them in one set, a more concise semi-active optimal control strategy is presented, so as to bypass the aforementioned drawback. Next, a strong databa
Semi-supported steel shear walls (SSSW), whose steel plate is connected to secondary columns rather than main columns of the frame, have been considered as an alternative steel shear walls to the traditional type. Many investigations have been made for proportionate designing of components of SSSW system. One of the important issues in this regard is the out of plane buckling of the secondary columns. In this paper, the plastic theory of structures is utilized to find out the axial force distribution, along the compressive column. Then, using energy method, for an assumed shear wall with specific geometry and material and a given shear force, the maximum overturning moment that makes the compressive secondary column buckles, can be determin
In this paper, elastoplastic analyses of plane-stress and plane-strain structures are addressed. The traditional von Mises yield surface is assumed in the material constitutive model and its piecewise-linear (PWL) approximation is derived. An associated flow rule is adopted and a consistent linear mixed hardening rule is developed in the so called mixed formulation. The relevant mathematical programming (MP) problem, which aims at the maximization of the linear combination of plastic multipliers, is constructed. Restricted basis linear programming (RBLP) is used to solve the MP problem, while special provisions are accounted for to obtain nonholonomic solutions. In order to reduce the required storage space, the Revised Simplex method and a
This study focuses on the seismic vulnerability assessment of process towers. A 96‐m process tower, located at the Shazand Refinery, is considered for a case study sample. The vulnerability of this structure is expressed with the development of fragility curves, which provide the probability of exceeding a prescribed level of damage for a wide range of ground motion intensities. The methodology of developing fragility curves for process towers is shown. The developed fragility curves can be very useful for emergency management agencies and insurance companies wishing to estimate the overall loss after an earthquake. The vulnerability of nonstructural equipments of tower is also assessed in subsequent step. To model the process tower with
This paper is concerned with nonlinear analysis of frames composed of softening materials. The previously proposed dissipated energy maximization approach is extended to determine non-holonomic solution of such frames. The adopted assumptions are: linear kinematics, lumped plasticity with softening behavior, piecewise-linear yield functions, associate flow rule and isotropic evolution with a three phase linear softening rule. The approach is based on a mathematical programming formulation. The solution procedure is discussed and presented in a comprehensive flowchart. It is shown that this method has the ability of solving and tracing path dependent problems and detecting any possible bifurcation.
Due to high capacity and low energy consumption of Magneto-Rheological (MR) dampers, they are vastly being utilized to control seismic responses of structures. Presenting more precise methods for control algorithm, and including more realistic physical characteristics of MR dampers (eg nonlinearities, uncertainties and…) will help engineers to employ this kind of damper more efficiently. In order to achieve a controller that quickly and accurately determines the input voltages to the MR dampers, in this paper, a new strategy is proposed. The proposed strategy utilizes Adaptive Network based Fuzzy Inference System,(ANFIS) for optimal control of structures that are equipped with MR dampers. To obtain optimal time histories of demanded volta
The optimization approaches, known as powerful tools in nonlinear analysis of structures, are considered in this paper for further development. Adopting linear kinematics, proportional loading, lumped plasticity, piecewise-linear yield loci, perfect plasticity and associated flow rule as the basic assumptions, the nonlinear analysis of a framed structure is formulated in the form of a mathematical programming problem. Dissipated energy is considered as the objective function and is maximized using the conventional simplex method with special provisions to obtain exact structural responses. The proposed algorithm is validated and outlined using several numerical examples taken from the literature.
This paper aims to ponder the effect of fuzzy uncertainties on performance evaluation of steel moment frame structures. Since the performance evaluation of a structure depends on its seismic demand and capacity spectra, any uncertainties in these two spectra causes uncertainty in performance level and performance point. Among many sources of uncertainties in structural dynamic analysis, in this paper, the modulus of elasticity, gravity load on the structure, dynamic properties of structure and soil properties have been considered and treated as fuzzy variables. To investigate the effect of these uncertainties, first, a nonlinear static pushover analysis program was written in MATLAB medium. Then, fuzzy inference model was used for determina
During the recent past decade semi-supported steel shear walls (SSSW) have been introduced as an alternative to the traditional type of steel plate shear walls. In this system the shear wall does not connect directly to the main columns of the building frame; instead it is connected to a pair of secondary columns that do not carry vertical gravity loads. In this paper, the interaction between the wall plate and the surrounding frame is investigated experimentally for typical SSSW systems in which the wall-frame has a bending-dominant behavior. Based on the possible storey failure mechanisms a simple method is proposed for design of the floor beams. A quasi static cyclic experimental study has been performed in order to investigate the colla
In this paper the nonlinear analysis and design optimization of guyed masts is addressed. The mast is modeled as a 3D truss and is supported by catenary cable elements that have nonlinear elastic behavior. For nonlinear static analysis, an innovative procedure is proposed that divides the structure into linear and nonlinear parts and analyzes them separately. The proposed method satisfies the equilibrium and compatibility by establishing and solution of a set of nonlinear equations. The optimization problem employs the sizes of members, initial cable tensions and the positions of anchor on the ground and tie level of cables on the mast as design variables. To facilitate the optimization solution, a compatible sensitivity anal
In this paper, a fuzzy rule‐based semi‐active control of building frames using semi‐active hydraulic dampers (SHDs) is presented. The SHDs are installed between the top of a Chevron bracing and the upper beam on each story to prevent damage to the structure from severe earthquakes. The set of Chevron brace and SHD is modeled as a Maxwell element that consists of a damping element in series with a spring. The rule extraction strategy for semi‐active fuzzy control is carried out by genetic algorithm (GA). The objective is to minimize both the maximum inter‐story drift and absolute acceleration responses of the structure. Interactive relationships between structural responses and damping coefficients of SHDs are established by using
In this chapter, the reader gets acquainted with the philosophy of performance-based design, its principles, and an overview of the procedures for performance evaluation of structures. The essential prerequisites of optimal performance-based design, including nonlinear analysis, optimization algorithms, and nonlinear sensitivity analysis, are introduced. The methods of nonlinear analysis and optimization are briefly presented, and the formulation of optimal performance-based design with emphasis on deterministic type, rather than probabilistic-(or reliability)-based formulation is discussed in detail. It is revealed how real performance-based design is tied to optimization, and the reason is given for why, without optimization algorithms, m
In this paper, the semi-supported steel shear wall (SSSW) that has been proposed as an alternative to the traditional type of steel shear wall is introduced. The problem of calculating the ultimate capacity of shear walls (with emphasis on its semi-supported type) is addressed. A new method for evaluating the ultimate shear capacity of given SSSW especially when it undergoes bending moments is proposed. The method determines the maximum shear capacity based on the lower bound theory of plastic design. The obtained results of this approach are compared to those of the finite element method (FEM). The comparison shows that the proposed method produces similar results to finite element analysis; meanwhile it is much faster and requires less co
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