EARTHQUAKE RESPONSES OF SECONDARY SYSTEMS IN BASE-ISOLATED STRUCTURES

This paper presents the results of a series of numerical simulation studies on seismic responses of secondary systems in base-isolated structures including equipment-structure in-teractions. A three-story building is used as the primary structure, while the equipment is modeled as a single-degree-of-freedom linear system. A number of base isolation systems such as the Laminated Rubber Bearing, the Pure Friction, the Resilient-Friction, and the Electricite de France systems are considered. Several earthquake records including the NOOW component of El Centro ۱۹۴۰ and the S۱۶E component of Pacoima Darn ۱۹۷۱ earthquakes are used as ground accelerations. Acceleration and deflection response spectra of the secondary system under different conditions are evaluated and the effects of equipment-structure inter-actions are studied. It is shown that the use of base isolation provides considerable protection for structural contents. However, peak responses of the secondary systems vary substantially depending on the base isolation system used. Among the base isolation systems considered, the Laminated Rubber Bearing system appears to be remarkably effective in reducing peak responses of secondary systems under a variety of conditions.