Seismic response of SMA-based self-centering buckling-restrained braced frames under near-fault ground motions

Abstract

Self-centering buckling-restrained braces (SC-BRBs) consisting of BRBs as the primary load-resisting elements and shape-memory alloy (SMA) bars as the supplemental re-centering elements have shown the higher axial resistance in tension and compression along with negligible residual deformation under cyclic loading. Superplastic characteristics of Nickle and Titanium (NiTi) SMA bars provide the self-centering mechanism, which minimizes the residual drift response of buckling-restrained braced frames (BRBFs) under earthquake loadings. The present study is focused on the seismic performance of low to high-rise BRBFs equipped with SC-BRBs, conventional BRBs, and Hybrid braces (i.e., a combination of BRBs and SC-BRBs) under near-field ground motions. 3-story, 9-story, and 20-story frames with both moment-resisting and non-moment-resisting beam-to-column connections have been considered in this study. Nonlinear dynamic analyses have been carried out on eighteen nos. of numerical models developed using a computer software OpenSees for a set of forty near-field ground motions. Though SC-BRBFs exhibited negligible residual drift response, they showed a higher peak interstory drift ratios as compared to BRBFs. Low-rise BRBFs with pinned beam-to-column connections are found to be more vulnerable to failure under near-fault ground motions. The use of Hybrid frames resulted in the improved seismic performance of 9-story and 20-story building frames.