Force-Based vs. Direct Displacement-Based Design of Buildings with Seismic Isolation

Abstract

A displacement-based design (DBD) procedure for buildings equipped with seismic Isolation Systems (IS’s) is proposed. It has been derived from the Direct DBD (DDBD) method recently developed by Priestley and co-workers. The key aspect of the proposed procedure is the definition of a target displacement profile for the structure. It is assigned by the designer in order to accomplish given performance levels, expressed in terms of maximum IS displacement and maximum interstorey drift. The proposed design procedure has been developed for different idealized force-displacement cyclic behaviours, which may be used to describe the response of a wide variety of IS’s, including: Lead-Rubber Bearings, High-Damping Rubber Bearings, Friction Pendulum Bearings and combinations of Flat Sliding Bearings with different re-centring and/or dissipating auxiliary devices. In this paper the background and implementation of the proposed design procedure are presented.