ROBUSTNESS ANALYSIS OF BASE-ISOLATED SYSTEMS

The study aims at evaluating the seismic robustness of a 3D reinforced concrete structure isolated by single-concave friction pendulum system (FPS) devices comparing the seismic reliability of different models related to different configurations in the case of the seismic isolator malfunctions. For the seismic reliability assessment, the elastic response pseudo-acceleration corresponding to the isolated period is considered as the relevant random variable and the input data have been defined by means of the Latin Hypercube Sampling technique. In this way, 3D inelastic time-history analyses have been performed and 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 for the different failure cases of the seismic isolators. Moreover, the seismic robustness of the abovementioned r.c. structural system has also been examined 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 in the case of a malfunction of a seismic device and provide useful design recommendations for base-isolated structures equipped with FPS.