A Novel Seismic Base Isolation System Consisting of a Lead Rubber Bearing in Series with a Friction Slider. Part II: Application to a Multi-Storey RC Building and Comparison with Traditional Systems

Abstract

In a parallel paper a new High Damping Hybrid Seismic Isolator (HDHSI) has been proposed and obtained by the assembly in series of a Lead Rubber Bearing (LRB) and a Friction Slider (FS) characterized by a high friction coefficient. In the present paper, within the context of seismic base isolation techniques for the earthquake resistance of Reinforced Concrete (RC) buildings, a multi-storey RC building is analyzed as base isolated by the seismic isolator HDHSI (High Damping Hybrid Seismic Isolator). The seismic response of this base isolated RC building is compared with the seismic response of the same structure isolated by a LRB (Lead Rubber Bearing) isolator. The analysis is developed by considering different seismic events in terms of intensity and in terms of frequency content with regard to a supervening collapse. The purpose of this comparative analysis is to highlight the features offered by the HDHSI system compared to the LRB system in the seismic protection of structures. Accordingly, a nonlinear dynamic analysis is performed for a RC structure base isolated by means of the proposed device. In the analysis anomalous seismic events are considered. They are the El Centro earthquake (N00W component, 1940) which is characterized by high intensity and the Erzincan earthquake (N90W component, 1992) which is characterized by anomalous frequency content. The comparison between the two base isolation systems is presented by analyzing the time history of the shear force and the time history of the displacement at the base of the superstructure. The benefits of the HDHSI system in conferring protection to the structure are shown to be significant even under extreme seismic events.