Seismic reliability analysis of 3D base-isolated structures through FPS with non-linear superstructure

The aim of the study consists in evaluating the seismic reliability of a 3D non-linear base-isolated structure with FP isolators considering the non-linear behavior of the overall system (superstructure, substructure and isolation level) for different values of the isolation degree and assuming both isolator properties (i.e., coefficient of friction) and earthquake main characteristics as random variables. Assuming appropriate probability density functions for each random variable and adopting the LHS method for random sampling, the input data set has been defined. Several 3D non-linear dynamic analyses have been performed considering both the vertical and horizontal components of each seismic excitation in order to evaluate the system performance and the exceeding probabilities (structural performances) at each level. Estimating the reliability of the superstructure, substructure and isolation level led also to define reliability-based abacus and equations useful to design the FP system depending on the isolation degree by considering the non-linear interaction between the superstructure, substructure and FP bearings.