A base isolation system for structures subject to extreme seismic events characterized by anomalous values of intensity and frequency content

The purpose of the analysis is to highlight the features offered by the proposed HDHSI base isolation system compared to the traditional LRB base isolation system in the seismic protection of structures. Nonlinear dynamic analyses are performed for base isolated multi-storey RC structures. In the analysis the inputs of different seismic events are adopted which can be considered as extreme events in terms of peak ground acceleration and in terms of frequency content. The seismic records are related to seismic events obtained by suitably amplifying the El Centro earthquake. They are characterized by their high values of the peak ground acceleration. Another seismic event considered in the analysis is the Erzincan earthquake which is characterized by high energetic content at low frequencies. Accordingly, the seismic events adopted in the analysis are characterized by anomalous values of intensity and frequency content. A nonlinear dynamic analysis is illustrated for a multi-storey RC building base isolated by the proposed HDHSI system compared with the traditional LRB base isolation system. The time history of the base shear and the time history of the base displacement of the superstructure are illustrated for the different analyzed seismic events. The benefits of the presented composite HDHSI base isolation system are shown to be appropriate in conferring a suitable seismic protection to multi-storey RC buildings even under extreme seismic events.