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M. Tahamouli Roudsari,M. Gordini,H. Fazeli,B. Kavehei 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.3
Load carrying capacity of reticulated space structures majorly depend on the structures’ imperfections. Imperfections in initial curvature, length, and residual stress of members are all innately random and can affect the load-bearing capacity of the members and consequently that of the structure. The present study investigated the effect of the probability distribution of initial curvature imperfection and lack of fit of members on the load-bearing capacity of double-layer barrel vault space structures with different types of support. A random number was first assigned to each member using gamma and normal distributions for initial curvature and member length imperfections, respectively. Afterwards, the ultimate bearing capacity and the collapse behavior of the structure was determined using nonlinear finite-element analysis in OpenSees software and finally structures reliability was acquired. The results demonstrate that the collapse behavior of doable-layer barrel vault space structures is sensitive to the random distribution of initial imperfections.
Experimental and Numerical Assessment of Reduced IPE Beam Sections Connections with Box-Stiffener
M. Tahamouli Roudsari,H. Jamshidi K.,SH. Moradi 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.1
Reduced Beam Section (RBS) is a new type of connection in steel moment resistant frames that was introduced after the Northridge earthquake of 1994. The application of RBS connections associated with reduced beam flange width can aid in accelerating web, flange, and lateral-torsional bucklings in the beam. To fix this problem, a new type of stiffener called the boxstiffener was presented in this study, which exactly encases the reduced portion of the beam. First, 4 laboratory tests were performed on RBS connections made of IPE140 and IPE270 sections in the two conditions of ‘with’ and ‘without’ a boxstiffener. Laboratory results showed that the stiffener considerably enhanced the connection ductility without a significant increase in the connection’s resistance. To examine other sizes of IPE sections, a verified Finite Element model was utilized. The results of the numerical models also confirmed the suitable performance of the box-stiffener.
M. Tahamouli Roudsari,M. Torkaman,L. Shirkhani,M. R. Nasimi,M. Mirzaei 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.6
In recent years, Steel Plate Shear Walls, a seismically resistant system with the ability to increase the energy dissipation capacity, have been widely employed. In the present work, with the aim of assessing and improving the seismic parameters of moment resisting frames with steel shear walls, four experimental samples (a special steel moment resisting frame, a moment resisting frame incorporating a thin steel shear wall, a moment resisting frame with steel shear wall and short UNP stiff eners, and a moment resisting frame with steel shear wall and buckling-resistant knee brace) were investigated. The samples were subjected to quasi-static pushover loading until the drift of 10% was reached. Then, based upon verifi ed Finite Element models, the eff ect of axial loading on the seismic parameter of the frames including eff ective stiff ness, ultimate strength, ductility, strength reduction factor, and energy dissipation capacity was evaluated. The results showed that UNP stiff eners exert a signifi cant infl uence on the seismic behavior of moment resisting frames with steel shear walls and therefore they are recommended to be used in regions with high seismic risk.
M. Tahamouli Roudsari,F. Abdollahi,H. Salimi,S. Azizi,A. R. Khosravi 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.4
Reduced Beam Section (RBS) connections are a new type of connection which have been used in steel moment-resisting frames since the 1994 Northridge earthquake. This study is primarily aimed at analyzing the effects of suitable web stiffeners on preventing the deterioration effect of the hysteresis curve for RBS connections. Results of more than 183 nonlinear finite element analyses on different IPE sections with radius cut, straight cut, and drilled-flange RBS connection showed that different web stiffeners considerably contribute to the enhancement of seismic performance of RBS connections. In this research, the effects of factors such as the geometry and the number of the stiffeners, the distance between the stiffener and column side, and the length and thickness of the stiffener on the seismic performance of RBS connections were also studied.