Robust Optimum Design for Hybrid Vibration Control of Structures under Multihazard Scenarios of Earthquakes and Winds

Vibration control of structures under multiple hazards poses severe problems due to the inherent variability in the features of the different hazards. A robust optimum design of a hybrid vibration controller (HVC) comprising unbonded fiber-reinforced elastomeric isolators (UFREIs) and tuned mass dampers (TMDs) is proposed for the vibration control of structures under multihazard scenarios involving earthquakes and winds. Essentially, the role of the UFREI-based isolation system is to restrict the structural acceleration responses against earthquake excitations, and the aims of the TMDs are to reduce the earthquake-induced base displacements and wind-induced acceleration responses of the UFREI-isolated structure. Two TMDs are utilized, one at the base floor to control the excessive base displacements and the other at the top floor to diminish the structural acceleration responses. A novel risk-informed objective is formulated to attain the optimum design of the HVCs, considering the return periods of the various hazards. Subsequently, Bayesian optimization is used to obtain the optimum HVC parameters deterministically and also probabilistically, considering the uncertainties in the structural parameters. The robustness and performance of the optimally designed HVCs are examined under an ensemble of earthquake and wind excitations. Further, the efficacy of the proposed robust optimum HVC is demonstrated on a real-life hospital building. Results conclude that the probabilistic optimum HVC could effectively control the structural acceleration responses under the considered multihazard scenario, at the same time ensure that the base displacement of the HVC-controlled structure never exceeds the base displacement of the UFREI-isolated structure, under various uncertain scenarios.