Robustness analysis of 3D base-isolated systems

The aim of the study consists of evaluating the seismic robustness of a 3D r.c. structure equipped with single-concave friction pendulum system (FPS) devices in reliability terms considering differ-ent models related to different malfunctions of the seismic isolators. The elastic response pseudo-acceleration corresponding to the isolated period is assumed as the relevant random variable and, by means of the Latin Hypercube Sampling technique, the input data have been defined in order to perform 3D inelastic time-history analyses. In this way, bivariate structural performance curves at each level of the r.c. structural system as well as seismic reliability-based design abacuses for the FP devices have been computed and compared in order to evaluate the robustness of the r.c. system considering different models related to the different failure cases analysed. Contextually, the seismic robustness of the abovementioned r.c. structural system has also been ex-amined by considering both a configuration equipped with beams connecting the substructure columns and a configuration without these connecting beams in order to demonstrate their effectiveness in improving the seismic robustness for a malfunction of a seismic device and provide very useful design recommendations for base-isolated structures equipped with FPS.