Optimal Design of Superelastic Lead Rubber Bearing (SMA-LRB) for Vibration Control of Building Under Blast-Induced Ground Motion (BIGM)

The shape memory alloy (SMA) supplemented base isolation (BI) systems have emerged as promising hybrid control devices for mitigating blast-induced vibration in structure. Compared to conventional BI systems, SMA-based BI systems enhance the control efficiency, in conjunction with substantially reduction of isolator peak and residual displacement. This study emphases on optimized design of superelastic SMA lead rubber bearing (SMA-LRB) system considering the effect of limitation in isolator peak displacement, under blast-induced ground motion (BIGM), which has not been addressed previously. The constrained optimal design results and their associated responses are then compared with the unconstrained solution. Furthermore, the optimal design and performance of SMA-LRB isolator have been compared with the LRB isolator. The nonlinear time history analysis (NLTHA) is conducted on linear elastic shear building isolated with nonlinear isolation system. The parametric Bouc–Wen model is utilized to capture the hysteresis behavior of lead core. Nonlinear force–deformation relation of SMA wire has been represented through a thermo-mechanical model. The study’s findings reveal that the presence of constraints significantly increases the required optimal normalized strength of lead core and SMA wire. For LRB isolator, this increase is more pronounced than SMA-LRB isolator. In comparison with the LRB system, SMA- LRB system exhibits a greater top-floor peak acceleration controllability, reducing it by 4% to 32% for constrained designs and 4% to 30% for unconstrained designs. Additionally, the unconstrained optimization case demonstrates that SMA-LRB shows 6% to 70%, and 19% to 71% less peak and residual isolator displacement than LRB. Thus, SMA-LRB systems demonstrate superior performance in reducing the vibration of isolated system under BIGM, than LRB system.