Loading...
Search for:
zarfam--panam
0.036 seconds
Estimating the Seismic Reliability of the Structures Based on Modal Nonlinear Probabilistic Analysis
, Ph.D. Dissertation Sharif University of Technology ; Mofid, Massoud (Supervisor)
Abstract
Concerning the variety of existing buildings and the diversity in the factors which affect the behaviors of structures, subjected to earthquakes, presenting a definite method for studying their seismic vulnerabilities has not been realized yet. Selecting a method which covers all mentioned necessities is extremely wide and complex. From one side, the capacity of structural system should be determined based on its strength and deformability. On the other hand, the nonlinear behavior of structure should be predicted by selecting the probable effects of earthquake on the region. Then, the force or acceleration which causes damage of structure's components, and the whole structural system,...
Active Control of beams/Plates on Elastic Foundation under the Effect of Random Loadings
, Ph.D. Dissertation Sharif University of Technology ; Khalu, Alireza (Supervisor)
Abstract
The dynamic behavior of beams and rectangular plates on elastic foundation under the effect of deterministic and random excitations is investigated in the cases of controlled and uncontrolled systems. The equations of motion are developed in each case in both deterministic and stochastic states. In all cases, the eigenfunction expansion method is used to solve the obtained equations.Moreover, the classical linear optimal control algorithm with displacement-velocity is considered to achieve the required control efforts. The applied dynamic excitations are supposed as moving loads, moving masses accompanied with random lateral excitations of supports and the uniform distributed linear loading...
On the modal incremental dynamic analysis of reinforced concrete structures, using a trilinear idealization model
, Article Engineering Structures ; Volume 33, Issue 4 , 2011 , Pages 1117-1122 ; 01410296 (ISSN) ; Mofid, M ; Sharif University of Technology
2011
Abstract
In order to estimate the seismic demands at the performance level, the inelastic behavior of concrete structures should be considered. Incremental dynamic analysis (IDA) based on a nonlinear response time history analysis (NL-RHA) is considered to be the most accurate method in seismic demand calculations. However, modal incremental dynamic analysis (MIDA), based on the equivalent single-degree-of-freedom (SDF) oscillator, is also often used in studying structural engineering performances. As the MIDA method has usually not been applied to reinforced concrete (RC) structures, in this study an attempt is made to investigate the performances of RC frames and to compare the results obtained...
Evaluation of modal incremental dynamic analysis, using input energy intensity and modified bilinear curve
, Article Structural Design of Tall and Special Buildings ; Volume 18, Issue 5 , 2009 , Pages 573-586 ; 15417794 (ISSN) ; Mofid, M ; Sharif University of Technology
2009
Abstract
In this paper, a technique for the study of nonlinear performance of structures in different levels of earthquakes is developed. In this method, the Incremental Dynamic Analysis (IDA) curves are not achieved from nonlinear dynamic analysis of multi-degree-of-freedom (MDF) structure. However, the procedure of constructing these curves is based on modelling of the entire structure with several single-degrees-of-freedom (SDF) structures and evaluating them through the modal pushover analysis method. An innovative idea for approximating pushover curves that is based on error distribution is introduced in this investigation. Furthermore, the total input energy applied towards the SDF oscillator,...
On the assessment of modal nonlinear pushover analysis for steel frames with semi-rigid connections
, Article Structural Engineering and Mechanics ; Volume 32, Issue 3 , 2009 , Pages 383-398 ; 12254568 (ISSN) ; Mofid, M ; Sharif University of Technology
2009
Abstract
Applying nonlinear statistical analysis methods in estimating the performance of structures in earthquakes is strongly considered these days. This is due to the methods' simplicity, timely lower cost and reliable estimation in seismic responses in comparison with time-history nonlinear dynamic analysis. Among nonlinear methods, simplified to be incorporated in the future guidelines, Modal Pushover Analysis, known by the abbreviated name of MPA, simply models nonlinear behavior of structures; and presents a very proper estimation of nonlinear dynamic analysis using lateral load pattern appropriate to the mass. Mostly, two kinds of connecting joints, 'hinge' and 'rigid', are carried out in...
Vibration control of beams on elastic foundation under a moving vehicle and random lateral excitations
, Article Journal of Sound and Vibration ; Volume 331, Issue 6 , March , 2012 , Pages 1217-1232 ; 0022460X (ISSN) ; Khaloo, A. R ; Sharif University of Technology
2012
Abstract
The formulation of three-dimensional dynamic behavior of a Beam On Elastic Foundation (BOEF) under moving loads and a moving mass is considered. The weight of the vehicle is modeled as a moving point load, however the effect of the lateral excitation is considered by modeling: (case 1) a lateral moving load with random intensity for wind excitation and (case 2) a moving mass just in lateral direction of the beam for earthquake excitation. A Dirac-delta function is used to describe the position of the moving load and the moving mass along the beam. The beam foundations are considered as elastic Winkler-type in two perpendicular transverse directions. This model is proposed to investigate the...
Erratum: Vibration control of beams on elastic foundation under a moving vehicle and random lateral excitations (Journal of Sound and Vibration 331 (2012) (1217-1232))
, Article Journal of Sound and Vibration ; Volume 331, Issue 11 , May , 2012 , Pages 2712- ; 0022460X (ISSN) ; Khaloo, A. R ; Sharif University of Technology
2012
Abstract
The formulation of three-dimensional dynamic behavior of a Beam On Elastic Foundation (BOEF) under moving loads and a moving mass is considered. The weight of the vehicle is modeled as a moving point load, however the effect of the lateral excitation is considered by modeling: (case 1) a lateral moving load with random intensity for wind excitation and (case 2) a moving mass just in lateral direction of the beam for earthquake excitation. A Dirac-delta function is used to describe the position of the moving load and the moving mass along the beam. The beam foundations are considered as elastic Winkler-type in two perpendicular transverse directions. This model is proposed to investigate the...
On the response spectrum of Euler-Bernoulli beams with a moving mass and horizontal support excitation
, Article Mechanics Research Communications ; Volume 47 , January , 2013 , Pages 77-83 ; 00936413 (ISSN) ; Khaloo, A. R ; Nikkhoo, A ; Sharif University of Technology
Elsevier Ltd
2013
Abstract
Abstract In this study, the response spectrum of a time-varying system such as a beam subjected to moving masses under a harmonic and earthquake support excitations is explored. The excitations are supposed to act on the horizontal directions of the beam axis. The inertial effect of the moving masses on the natural frequencies of the beam for different cases of loading is investigated and a critical value of a so called parameter "mass staying time" is presented to avoid dynamic instability of the system. Finally, some 3D response spectra for different supports excitations as well as the beam natural frequencies are depicted
Application of differential quadrature method to investigate dynamics of a curved beam structure acted upon by a moving concentrated load
, Article Indian Journal of Science and Technology ; Volume 5, Issue 8 , 2012 , Pages 3085-3089 ; 09746846 (ISSN) ; Kananipour, H ; Chavoshi, H ; Zarfam, R ; Sharif University of Technology
2012
Abstract
Application of curved beams in special structures requires a special analysis. In this study, the differential quadrature method (DQM) as a well-known numerical method is utilized in the dynamic analysis of the Euler-Bernoulli curved beam problem with a uniform cross section under a constant moving load. DQ approximation of the required partial derivatives is given by a weighted linear sum of the function values at all grid points. A prismatic semicircular arch with simply supported boundary conditions is assumed. The accuracy of the obtained results is corroborated by employing the Galerkin and finite element methods. Finally, the convergence rate of the DQM and Finite Element Method (FEM)...