Numerical study for the impact of torsional amplification on the seismic response of self-centring braces equipped with different shape memory alloy materials

Superelastic shape memory alloy (SE-SMA) becomes an emerging structural material in earthquake engineering to improve the seismic performance of structures located in high seismic zones. This paper aims first to compare the seismic response of self-centring braces equipped with five different SE-SMA materials. A three-story building located in Los Angeles, California, is selected for this study. A three-dimensional (3D) numerical model for the SE-SMA buildings is developed using OpenSEES software, and the seismic response is assessed under different ground motion intensities and directions. Subsequently, the torsional amplification effect is compared by adjusting the building centre of mass from the rigidity centre to demonstrate each SMA type's effectiveness. Results indicate that all studied buildings exhibited a negligible RIDR at the design level, whereas the SMA-FRP material mitigates the inter-story drift ratio (IDR) and residual inter-story drift (RIDR) relative to other SMA buildings at severe earthquake level. Results also highlight the SMA-FRP braces' capability to function at different mass eccentricity.