Seismic Isolation Using Slide and Rubber Bearings: Large Amplitude Free Vibration Tests on "Rapolla Residence Building"

An application of a mixed seismic isolation system (slide bearings for isolation and steel rubber bearings to have a recentering force) is presented. Such technique has been applied to a residence building, built in Italy at Rapolla (PZ- Basilicata). The application has allowed to investigate, through a series of dynamic Snap-Back tests, the behaviour of base isolated structure with only elastomeric bearings or with joined system (slide bearings and elastomeric bearings). Tests were carried out by using a mechanical device purposely designed to give the initial displacement, of the order of design base drift equal to 180 mm, to the building and then produce free damped vibrations acquired by using an accelerometer station. As far as the protection level is concerned, the seismic response of the structure on the mixed isolation system has been compared with that of the structure mounted on a steel rubber isolation system, confirming the effectiveness of the slide bearing technique