Optimally Robust Reliability-Based Design of Base Isolation Control System in Nonlinear Structures Considering Uncertainties

The seismic performance of isolated structures depends on the properties of base isolation devices like lead rubber bearings (LRB). Determining the optimal LRB parameters to achieve favorable seismic behavior involves solving optimization problems. To address uncertainties arising from variations in geometrical and mechanical parameters of the structures, reliability analysis is essential in the design process. This study employs two strategies for the optimal design of LRB: metaheuristic-based and reliability-based design optimization (RBDO). In the RBDO method, a double-loop approach combining meta-heuristic algorithms and reliability analysis is used, with a constraint according to the target reliability index. To analyze isolated structures, a nonlinear time history dynamic analysis method is employed, while the LRB isolator's nonlinear behavior is simulated using a bilinear hysteresis model. Mechanical properties of the LRB are considered as design variables. Through sensitivity and reliability analysis, the study assesses the impact of uncertainties and their significance in determining the system's reliability. The results highlight that the strategy of RBDO effectively designs LRB with a remarkable performance in reducing seismic responses.

Keywords:

Base Isolation , Lead Rubber Bearing , Optimization , Uncertainty , Reliability