Seismic Response of Resilient Steel Frame with Self-Centering SMA Brace

An innovative self-centering shape memory alloy (SMA) brace aiming at improving the seismic performance and self-centering capacity of steel frame structures is proposed in this paper. A series of cyclic loading tests with six self-centering SMA brace (SC-SMAB) specimens was carried out to investigate the effects of SMA area, bolt torque and initial SMA force on the hysteresis curves, energy dissipation and self-centering capacity. In addition, based on the experimental results, a numerical model of SC-SMAB with the improved Graesser and Bouc–Wen model was established and validated. Three different single-bay plan configurations of 9 storey steel frames including bare steel frame (BSF), steel frame with slip braces (SF-SB) and steel frame with SC-SMABs (SF-SCB) were analyzed to evaluate the seismic response. The test results show that the SC-SMAB with the bolt torque of 10 N M and initial SMA force of 5 kN has the maximum bearing force and self-centering capacity ratio. The established numerical model can accurately predict the seismic performance of the SC-SMAB. The inter-story drift ratio, roof displacement and roof acceleration of SF-SCB are lower than those of the BSF and SF-SB evidently, which decrease by 62.21%, 29.46% and 28.36% respectively from BSF. The hysteresis curve of SC-SMAB in the steel frame has nearly ideal flag-shape with high bearing force, good energy dissipation capacity, small residual deformation and outstanding re-centering capacity.