Seismic response of structures with friction pendulum inerter system (FPIS) under near-fault earthquakes.

This article focuses on improving the seismic performance of base-isolated structures subjected to near-fault ground motions by using a composite isolation system called FPIS, which combines a friction pendulum system (FPS) with an inerter system. Two mechanical layouts of the inerter subsystem—series-parallel inerter system-I-FPS (SPIS-I-FPS) and series-parallel inerter system-II-FPS (SPIS-II-FPS)—were analyzed using nonlinear time-history analyses solved via the fourth-order Runge-Kutta method. Results indicate that FPIS, particularly the SPIS-I-FPS designed based on the principle of maximum damping enhancement, more effectively reduces both the maximum displacement of the isolation layer and the acceleration response of the superstructure compared to traditional FPS or FPS combined with viscous dampers. The study recommends increasing the inerter system’s design parameters and maintaining the FPS friction coefficient within 0.05 to 0.10 to optimize seismic mitigation under near-fault excitations.