Dynamic response of frame structures with shape memory alloy -magnetorheological fluid-based bracing system by nonlinear time-history analysis

Bracing systems have been used for decades to enhance the structural integrity of the buildings against seismic loadings. Recently, studies have been conducted to explore the magnetorheological fluid (MRF) applications and the shape memory alloy (SMA) in bracing systems to improve their performance and functionality for structural stability under seismic loadings. In this study, SMA-based and MRF-based bracing systems are utilized to develop a new hybrid bracing system named the SMA-MRF-based bracing system. This hybrid system portraits the advantages of both systems. It is a state-of-art bracing system with controllable recovery ability and tunable energy dissipation capacity. To study its effect on the buildings' performance, a numerical model of a two-story frame is developed by the Open System for Earthquake Engineering Simulation (OpenSees) software. Then, nonlinear time-history analysis is performed to compare the modeled frame's results with and without the SMA-based, the MRF-based, and the SMA-MRF-based bracing systems under three simulated ground motion profiles. The comparison between drifts of all frames shows that using the SMA-MRF-based bracing system reduces the drift ratio by 50% and up to 85% compared to the structure without bracing.