Stochastic Optimization of a Nonlinear Base Isolation System with LRB and EIMD for Building Structures

Base-isolated structures achieve superior seismic performance but with the cost of large deformation base floor, which possibly causes superstructure collapse during severe earthquakes. Hence, it is great interest to develop hybrid isolation systems that can reduce and simultaneously improve superstructure’s performance. Recently, several using inerter-based dampers have emerged; however, nonlinear isolators has rarely been considered in these studies. In this paper, we conduct a stochastic optimization novel system lead-rubber bearings (LRB) electromagnetic inertial mass (EIMD). Based on Bouc–Wen hysteretic model LRB, derive semianalytical solutions response variances simplified base-isolated subjected stationary excitations. Then, based solutions, propose procedure for optimizing EIMD aimed at minimizing interstory drift. addition, investigate effect site conditions postyielding preyielding stiffness ratios LRB optimal parameters corresponding It found achieves better soft than firm site. Results building under artificial real earthquake excitations illustrate both response, outperforms conventional viscous (VD).