Near-field earthquake performance of SC-BRBs with optimal design parameters of SMA

摘要

Self-centering buckling-restrained braces (SC-BRBs) utilizing the re-centering potential of shape memory alloy (SMA) bars are used to control the excessive residual drift response of braced frames under seismic loading. The effectiveness of SC-BRBs in controlling the seismic response of a structure largely depends on the relative strength and stiffness of SMA bars and BRB core plates. This study is focused on determining the optimum length and prestressing force levels in SMA bars to maximize the hysteretic energy dissipation and re-centering behavior of SC-BRBs and evaluating the drift response of a medium-rise braced frame under near-field earthquake excitations. The seismic performance of SC-BRBs has been numerically investigated at both component (local) and frame (global) levels using a computer software OpenSees. Both length and prestressing force in SMA rods are varied in the numerical models to evaluate the axial resistance and hysteretic energy dissipation potential of SC-BRBs. The hysteretic response of SC-BRBs is compared with that of conventional BRBs. Nonlinear dynamic analysis has been conducted on a 9-story braced frame equipped with SC-BRBs as well as BRBs under forty near-field ground motion records. The seismic drift response of braced frames equipped with SC-BRBs with different prestressing force levels is compared with that of BRBF. Based on the findings of this study, the optimum geometric parameters of SMA bars have been proposed for the design of SC-BRBs. (C) 2020 Elsevier Ltd. All rights reserved.