Performance enhancement of FPS-isolated buildings using an inerter-based damper: Stochastic seismic analysis and optimization

Enhancing the seismic performance of based-isolated structures during a major earthquake event using inerter-based dampers emerges as a prominent research direction. However, analysis and optimization of based-isolated structures incorporated with inerter-based dampers considering both system nonlinearity and excitation uncertainty have rarely been reported. An electromagnetic inertial mass damper (EIMD) is a high-performance passive damper that consists of an inerter element and a damping element in parallel, and its superior control performance has been validated when applied to stay cables and frame structures. This paper presents a stochastic seismic analysis and parameter optimization of a friction pendulum system (FPS)-isolated structure with an EIMD considering the Kanai-Tajimi earthquake model. Considering the nonlinear damping of the FPS system, we derive the semi-analytical solutions of the FPS-isolated structure with an EIMD under stationary stochastic excitations based on a two-degree-of-freedom model using the statistical linearization technique. The effect of the EIMD on the FPS-isolated structure is systematically investigated via parametric study. A numerical procedure is proposed for optimizing the parameters of the EIMD and the FPS for minimizing the seismic response variances. Numerical simulation of a seven-story FPS-isolated building subjected to both artificial and real seismic excitations illustrates the effectiveness of the optimization procedure based on the semi-analytical solutions. Numerical results also reveal that the EIMD is capable of reducing both the base floor responses and superstructure responses, which outperforms tuned inerter dampers and conventional fluid viscous dampers. This study might shed light on the applications of inerter-based dampers in based-isolated structures in the years to come.