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Evaluation of hysteretic behavior of eccentrically braced frames with zipper-strut upgrade Seyed Mehdi Zahrai a, Milad Pirdavari b,⁎, Hamid Momeni Farahani b a Center of Excellence for Management and Engineering of Civil Infrastructures, School of Civil Engineering, College of Engineering, The Univ. of Tehran, P.O. Box 11365/4563, Tehran, Iran b Ati-Naghsh Hamraz Consultants, Inc. Suite 8, No. 73, Jalale Ale Ahmad, P.O. Box 1446665718, Tehran, Iran a r t i c l e i n f o a b s t r a c t Article history: Received 28 August 2012 Accepted 28 December 2012 Available online xxxx Keywords: EBF Zipper strut Hysteretic behavior Pushover analysis Finite-element Cyclic loading This paper describes the seismic behavior of Eccentrically Braced Frames (EBF) upgraded using zipper-struts which connect the mid-point of shear links in all stories. The numerical modeling of the zipper-strut-equipped model is conducted using finite-element method software under cyclic load, with the goal of evaluating the behavior of shear links. The interaction of shear links and zipper-struts is also studied. Furthermore, the prototypes are subjected to nonlinear static (Pushover) analysis in two configurations; one with moment-resisting connections and one with pinned connections. Finally, the increase of ductility coefficient for the prototypes with zipper-strut is studied. The prototypes are also subjected to time-history analysis using scaled earthquake records, with the purpose of studying the energy parameters of the models. The unbalanced shear force is distributed among all stories due to the added continuity among shear links. This results in the extension of structural displacement capacity according to acceptance criteria. Moreover, a noticeable delay occurs until shear links experience enough rotation to meet Collapse Prevention acceptance criteria. By imposing acceleration on the structure and conducting time history analysis, it is observed that the zipper-strut-equipped system shows a stronger tendency to form shear links, leading to greater dissipation capacity in plastic zone Journal of Constructional Steel Research 83 (2013) 10–20 منبع: [Hidden Content] دانلود: [Hidden Content] media.pdf