A model for hysteretic behavior of rhombic low yield strength steel added damping and stiffness Ming-Hsiang Shih a , Wen-Pei Sung b, * a Department of Construction Engineering, National Kaoshiang First University of Science and Technology, Kaoshiang 811, Taiwan, ROC b Department of Landscape Design and Management, National Chin-Yi Institute of Technology, Taichung 41111, Taiwan, ROC Received 24 April 2004; accepted 23 November 2004 Available online 20 January 2005 Abstract The Low Yield Strength Steel (LYS) has the superiority over long period of low cycle fatigue, high strain hardening rate and impressive ductility to overcome the local fracture problem existing in regular A36 steel plate. With elastoplas- tic characteristics and experimental verification, it becomes a good material considered for added damping and stiffness (ADAS) since the stress–strain relationship of LYS performs yielding much earlier than that of A36 steel. Thus, WenÕs Model and the bi-linear model, simulated for A36 energy absorber cannot properly analyze energy dissipation while A36 are replaced by LYS. Therefore, the modified WenÕs Model is proposed to reproduce the complicated nonlinear strain hardening in seismic resistance of rhombic LYS under reciprocating loading test. The numerical simulation and experimental data can match each other to reveal that the proposed model has capability in predicting the hyster- esis energy dissipation behavior of rhombic low yield strength steel plate. This model also can be easily integrated with a dynamic analysis program. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Modified WenÕs model; Hysteresis energy dissipation behavior; Seismic resistance of LYS; Dynamic analysis; Pseudo- dynamic tests 1. Introduction X [1,2] and triangular [3,4] type of steel plates both are most often selected for the earthquake resistant de- vice of adding damping and stiffness (ADAS). Neverthe- less, axial force and welded bond still influence these two types of devices. Meanwhile, it is hard to describe the force–deformation behavior of ADAS, especially when the strain hardening is occurred within nonlinear region of stress–strain diagram. Sozen [5] proposed that the hysteretic behavior of structure must be considered in the analysis model to expound the significant damping capability. To predict the hysteretic behavior of ADAS precisely, TsaiÕs team [2] suggested the elastic–perfectly plastic and elastic–linear work-hardening model to por- tray these phenomena. In order to enhance the energy dissipation capability of metallic damper, a new type of steel with low yield strength has been developed by China Steel Corporation Company. The investigation for this material shows that the ratio of the ultimate elongation is about 62% [6], yielding strength of LYS is below two thirds yielding strength of often-used steel 0045-7949/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.compstruc.2004.11.012 * Corresponding author. E-mail address: sung809@chinyi.ncit.edu.tw (W.-P. Sung). Computers and Structures 83 (2005) 895–908 www.elsevier.com/locate/compstruc