Modelling curved surface sliding bearings with bilinear constitutive law: effects on the response of seismically isolated buildings

This research work is related to the evaluations of some modelling assumptions of the stick–slip phase of the Friction Pendulum™ System (FPS) on the seismic response of base-isolated buildings. Although several theoretical and experimental research findings show the complexity of the FPS nonlinear behaviour, the current international seismic design codes allow the designer to model the FPS nonlinear response using simple bilinear constitutive relationship in order to reduce the computational effort for modelling and performing the analyses. Therefore, the problem that has to be faced by practitioners and researchers is related to the way of modelling the stick–slip phase and the corresponding friction phenomena with a simple bilinear constitutive model. This research work has been encouraged by some experimental evidence and performed for investigating, through a large parametric study, the influence that many modelling assumptions may have on the global and local responses of buildings. The study has been carried out without claiming to be innovative but for being a valuable tool in the design practice and, mainly, in modelling the nonlinear response of the FPS with the bilinear simplification allowed by design codes.