Protecting Base-Isolated Structures from Near-Field Ground Motion by Tuned Interaction Damper

This paper deals with the combined use of a low-damping base-isolation system and a semiactive control system referred to as a tuned interaction damper (TI damper). The TI damper generates friction-type forces (rigid-plastic behavior) through interactions between the primary isolated structure and an auxiliary structure. Because of its energy-dissipation nature, a base-isolated structure controlled by a TI damper is inherently stable, and as a semiactive control device, its operation requires only minimal external power. The efficacy of the proposed hybrid system is examined through a numerical simulation for a five-story scaled building subjected to near-field ground motions. A sensitivity analysis on the parameter dependence of the structural response on control force limit, stiffness ratio, and frequency ratio is presented. By tuning these parameters to optimal values, the performance of the base-isolated structure equipped with a TI damper can be enhanced. Based on the numerical simulation results, it is concluded that a TI damper is capable of suppressing the base drift of base-isolated structures subjected to near-field earthquake ground motions while maintaining the superstructure interstory drift and accelerations at small levels.