Cyclic Behavior Assessment of Steel Bar Hysteretic Dampers Using Multiple Nonlinear Regression Approach
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RESEARCH PAPER
Cyclic Behavior Assessment of Steel Bar Hysteretic Dampers Using Multiple Nonlinear Regression Approach Hashem Jahangir1 · Mansour Bagheri2 · Seyed Mohammad Javad Delavari2 Received: 5 March 2020 / Accepted: 1 October 2020 © Shiraz University 2020
Abstract Isolators prevent the transfer of earthquake energy to the structure and reduce its relative displacement by increasing the time period of the structure. Most isolators have low damping and hence, in some cases, the auxiliary dampers can play an important role in the increased damping and reduced displacement of the isolation system. In this paper, a new type of steel bar hysteretic dampers (SBHDs) as the auxiliary damper was studied and evaluated in the isolation systems. For this purpose, 1650 numerical models of SBHDs were constructed based on a laboratory sample with the bars of different length, number, and cross section. Also, the role of each of these geometric parameters in the seismic behavior of the dampers was evaluated using the hysteresis curves and the corresponding ideal bilinear curves. Owing to the deficiency of the analytical solutions in the estimation of the nonlinear behavior of SBHDs and to increase their accuracy, some models were proposed using the multiple nonlinear regression (MNLR) methods. The proposed relations can be used to obtain the displacements and the forces corresponding to the first yield point and the ultimate point, ductility ratio, elastic stiffness, post-yield stiffness, effective stiffness, and dissipated energy. The results showed that the proposed equations are able to estimate the cyclic behavior of SBHDs with the proper accuracy and well consistency, and can be used with full confidence. Keywords Steel bar hysteretic dampers · Hysteresis curves · Geometric parameters · Multiple nonlinear regression · Analytical relations
1 Introduction There are different methods for improving the seismic behavior of structures (Comartin et al. 1996). In the conventional methods, it is tried to increase the seismic capacity of a structure by adding some elements such as shear walls or steel braces to the structure. In this case, the lateral stiffness of the structure is increased, and the higher lateral * Mansour Bagheri [email protected] Hashem Jahangir [email protected] Seyed Mohammad Javad Delavari [email protected] 1
Civil Engineering Department, Ferdowsi University of Mashhad, Azadi Square, 9177948974 Mashhad, Razavi Khorasan Province, Iran
Department of Civil Engineering, Birjand University of Technology, Industry and Mining BlvdIbn Hesam Square, 9719866981 Birjand, South Khorasan Province, Iran
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stiffness will develop more forces in the main elements of the structure. An appropriate alternative method for improving the seismic behavior of structures can be the isolation of its bases from the supports. The philosophy of isolating a structure is different from the philosophy of strengthening the structural elements under the lateral load. In the isolated syst
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