Base Isolation Systems for Structures Subject to Anomalous Dynamic Events

Abstract

A base isolation system is investigated which is suitable for structures subject to dynamic events characterized by high intensity and critical values of frequency content. The analyzed base isolation system is defined as high damping hybrid seismic isolator since it is realized by the assembly in series of a lead rubber bearing isolator and a friction slider isolator characterized by a high friction coefficient. A nonlinear dynamic analysis is performed for a base isolated structure characterized by irregularity in plan. The base isolation system is designed to cope with extreme dynamic events in terms of peak ground acceleration and in terms of frequency content. A nonlinear dynamic analysis is performed for the considered base isolated structure by investigating the time history of the base shear and the time history of the base displacement of the superstructure for the different analyzed dynamic events. The characteristic features of the presented base isolation system are compared with the ones of a traditional lead rubber bearing base isolation system for the dynamic protection of structures. The advantages of the illustrated high damping hybrid base isolation system are shown to be useful for the safeguard of structures under extreme dynamic events in terms of peak ground acceleration and frequency content.