Multi-objective stochastic-structural-optimization of shape-memory-alloy assisted pure-friction bearing for isolating building against random earthquakes

• SMA-PF isolation system is employed for isolating building.
• Performance of SMA-PF system is assessed under random earthquakes.
• Optimal SMA-PF system is proposed by multi-objective optimization.
• Robustness of optimal bearing is verified under real earthquakes.
• SMA-PF is equally efficient as PF but largely reduces bearing displacement.

The optimal stochastic performance of pure friction system supplemented with SMA-restrainer (SMA-PF) is presented based on a framework of multi-objective optimization. The evaluation of system response for this is based on nonlinear random vibration analysis. The optimizing design variables are based on two mutually conflicting objectives, involving maximizing the isolation efficiency as well as isolator displacement. The proposed optimal design, thus, not only maximizes the isolation efficiency but also impose due consideration to the bearing displacement. The optimal bearing is shown to substantially reduce the bearing displacement with nominal sacrifice in isolation efficiency. Comparison of the multi-objective Pareto fronts reveals much facilitated trade-off among the mutually conflicting objectives in SMA-PF than in PF system. The viability of the optimal performance is further verified under recorded ground motions, which is observed to be in parity to the stochastic response behavior. The reduction in the residual bearing displacement is also observed.