Substructured pseudodynamic and cyclic tests on a seismic protection system including steel-Teflon bearings and fluid viscous devices

An experimental investigation was carried out on a base isolation system incorporating stainless steel-Teflon bearings, operating as sliders, and silicone fluid viscous spring-dampers. In this system, dampers are connected to the base-floor of an isolated building to provide the desired passive control of response in the superstructure, as well as to guarantee its complete re-centring after termination of a seismic action. Two types of experiments were conducted: sinusoidal and random cyclic tests, and a pseudodynamic test in “substructured” configuration. The cyclic tests were aimed at characterising the hysteretic response of the spring-dampers, the frictional behaviour of steel-Teflon bearings, and the combined response of their assembly. The pseudodynamic test simulated the installation of the protection system at the base of a three-story steel frame structure. The results of the performed tests, as well as of relevant mechanical interpretation and numerical simulation analyses, are presented in this paper.