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

摘要

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. Super-plastic 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.