Department of Earthquake Engineering (2005 - Present)
Civil Engineering, Structural Eng.
Dept. of Civil Eng., University of Tokyo, Tokyo, Japan
Civil Engineering, Earthquake Engineering
Dept. of Civil Eng., University of Tehran, Tehran, Iran
Civil Engineering
Dept. of Civil Eng., University of Tehran, Tehran, Iran
Prof. Masoud Soltani Mohammadi received his BSc and MSc from the University of Tehran and his Ph.D. in Structural Engineering from the University of Tokyo. He is currently a faculty member at the earthquake engineering department of Tarbiat Modares University.
Classic one-way shear design provisions began with 45 degrees truss analogy introduced by Ritter and then rectified by addition of a concrete contribution term (V c) which was basically based upon the results of some academic tests of simply supported RC beams with concentrated loadings. There are some strong evidence and examples that this empirical approach and the difference between its experimental base and the effective mechanisms in many of existing applications can be disastrous. Shear failure of reinforced concrete falls in the category of brittle and undesirable failure modes and has caused unrectifiable incidents in structures and infrastructures throughout the world. Some of such examples are the shear failures observed in the ev
In conventional engineering practice, the use of stiffeners and flanges on both faces of stiffened web panels for I-shaped link beams provides fully restrained boundary conditions. In tubular link beams, however, the stiffened web panels possess simply supported boundary conditions due to the use of single-sided stiffeners and flanges.This study investigates the boundary condition effects of stiffened web panels in tubular and I-shaped link beams on their rotation capacity assuming similar area, moment of inertia, length and stiffener spacing. Based on the numerical results, I-shaped link beams demonstrated an approximately 78% higher rotation capacity compared to tubular link beams under the same conditions which could be due to the better
Earthquake vulnerability is the major weakness of unreinforced masonry structures. Various methods have so far been proposed to strengthen such structures against earthquakes. The recommended procedures are not especially suitable for this type of structures, that are meanwhile historically and culturally valuable. One of the adequately suitable methods of retrofitting of this particular type of structures is the center-core technique; based on which the fa?ade of buildings with no change whatsoever. Scantly little studies have so far been conducted on structural retrofitting and the essential research carried out in this area has focused on the study of masonry piers. In this study, the in-plane nonlinear behavior of two full scale unreinf
The main purpose of this study is to investigate the structural behavior and cracking response of reinforced concrete (RC) members on the basis of Rigid Block and Spring Method (RBSM). The main problem of this method i.e. the independent evaluation of springs’ stiffness is discussed and modified based on the concept of smeared crack approach. The response of RC membrane element is evaluated by considering the stress transfer mechanisms involving axial behavior of the cracked/un-cracked concrete, axial behavior of the reinforcement and the stress transfer across cracks due to aggregate interlock. A non-iterative approach for estimating the reinforcing bars’ strains based on the shear strain of cracked RC domain is proposed using approxim
One of the oldest and most durable building materials used for a large number of ancient structures by mankind is the masonry material. Few maintenance costs of masonry building, as well as its proper resistance to fire, have caused to be the boost building materials nowadays. Two major modeling approaches for simulating the behavior of masonry members are micro-modeling (heterogeneous model) and macro-modeling (homogeneous model). In the micro-modeling approach, the failure mechanisms and cracking pattern are precisely determined; but because of the required specifications and details, it is considered as a sophisticated modeling approach. In this study, the main purpose is to develop micro-modeling approach based on a discrete element met
In this study, an equivalent fiber frame model based on an analytical method is proposed for masonry structures assessment. The equivalent frame model (EFM) is a simple applicable approach that is relatively accurate and bears a low computational cost. It holds proper convergence and adaptability compared to micro modeling methods. The progression of nonlinearity over the cross-section and along the height of masonry walls is simulated by proposed homogenized constitutive models. Moreover, a new procedure is proposed for the evaluation of unreinforced masonry walls strengthened with reinforced concrete layers. To examine the shear behavior (bed joint sliding mode of failure, and diagonal tension mode), an interface element based on a smeare
In recent years nonlinear static analysis method has been widely used in the field of performance based earthquake engineering. Whereas the capabilities of this method is well recognized, it still has inherent shortcomings. Accordingly, by considering aspects such as nonlinear properties of members, higher modes effect, and the computational cost, the accuracy of the method should be investigated. Although an enormous study have been carried out to improve the pushover analysis, the proposed methods are almost deterministic and cannot directly consider the seismic records uncertainties. Toward this challenge, the present study aims to examine the requirements of inelastic static analysis method through a comparison with incremental dynamic
This article presents a micromodeling computational framework for simulating the tensile response and tension-stiffening behavior of fiber reinforced polymer–strengthened reinforced concrete elements. The total response of strengthened elements is computed based on the local stress transfer mechanisms at the crack plane including concrete bridging stress, reinforcing bars stress, FRP stress, and the bond stresses at the bars-to-concrete and fiber reinforced polymer-to-concrete interfaces. The developed model provides the possibility of calculating the average response of fiber reinforced polymer, reinforcing bars, and concrete as well as the crack spacing and crack widths. The model, after validation with experimental results, is used for
Recently, the adaptive nonlinear static analysis method has been widely used in the field of performance based earthquake engineering. However, the proposed methods are almost deterministic and cannot directly consider the seismic record uncertainties. In the current study an innovative Stochastic Adaptive Pushover Analysis, called" SAPA", based on equivalent hysteresis system responses is developed to consider the earthquake record to record uncertainties. The methodology offers a direct stochastic analysis which estimates the seismic demands of the structure in a probabilistic manner. In this procedure by using a stochastic linearization technique in each step, the equivalent hysteresis system is analyzed and the probabilistic characteris
This research deals with the behavior of masonry piers made by fired bricks and gypsum-clay mortar, strengthened using centercore method. Compressive strength of masonry is evaluated along one year using 66 samples. Shear behavior of joints is defined using Mohr-Coulomb failure criterion; the friction angle and cohesion was measured using 54 triplet samples at 40-day age. Moreover, the cohesion is evaluated along one year using 66 triplet samples. Seven identical pier specimens were constructed and strengthened using centercore with two different retrofitting schemes (anchorage of the centercore to the base) and two different rebar sizes. All of the specimens were tested under cyclic in-plane loading. The retrofitted specimens without ancho
In this paper, the probabilistic seismic performance of vertically irregular steel buildings, considering soil–structure interaction effects, is evaluated. Various irregular distributions of structural properties, including mass, stiffness and strength along the height of three-dimensional moment resisting steel frames were intended. The finite element model of soil medium was created with solid elements below the structure. The nonlinear material behavior of soil was considered as well. Nonlinear incremental dynamic analysis was performed to evaluate the flexible-base structural performance in the framework of probabilistic performance-based earthquake engineering. According to the median curves of intensity demand of stru
This article focuses on the experimental and analytical investigations of masonry walls surrounded by tie-elements under in-plane loads. The experimental results of an unconfined and a confined masonry wall, tested under reversed cyclic lateral loads, are presented. For numerical study, a micro-modeling strategy, using smeared-crack-based approach, is adopted. In order to validate the numerical approach, experimental test results and data obtained from the literature are used, and through a systematic parametric study, the influence of adjoining walls and number of tie-columns on the seismic behavior of confined masonry panels is numerically assessed and a simple but rational method for predicting the nonlinear behavior of these structures
Seismic pounding between adjacent buildings with inadequate separation and different dynamic characteristics can cause severe damage to the colliding buildings. Efficient estimation of the maximum pounding force is required to control the extent of damage in adjacent structures or develop an appropriate mitigation method. In this paper, an analytical approach on the basis of statistical relations is presented for approximate computation of extreme value of pounding force between two adjacent structures with equal or unequal heights subjected to stationary and non-stationary excitations. The nonlinearity of adjacent structures is considered using Bouc-Wen model of hysteresis and the pounding effect is simulated by applying the nonlinear vis
This paper studies soil properties uncertainty and its implementation in the seismic response evaluation of structures. For this, response sensitivity of two 4- and 12-story RC shear walls to the soil properties uncertainty by considering soil structure interaction (SSI) effects is investigated. Beam on Nonlinear Winkler Foundation (BNWF) model is used for shallow foundation modeling and the uncertainty of soil properties is expanded to the foundation stiffness and strength parameters variability. Monte Carlo (MC) simulation technique is employed for probabilistic evaluations. By investigating the probabilistic evaluation results it's observed that as the soil and foundation become stiffer, the soil uncertainty is found to be less importan
Bridges normally undergo nonlinear deformations during a near-field strong ground motion resulting in a critical deviation of their columns from the plumb state due to considerable residual deformations. The conventional hysteresis models formulated for typical concrete columns are normally used for this purpose which most of times fail to correctly predict the residual deformations occurred as a result of a one-sided or directivity pulse excitation. The present research aims at development of a peak-oriented hysteresis model being able to regenerate residual deformations more reasonable compared with the conventional hysteresis models. This multi-linear peak-oriented model considers strength deterioration in each half cycle
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