Semi-active seismic isolation system with controllable friction dampers using piezoelectric actuators

Semi-active seismic isolation systems using controllable friction dampers had been proposed to reduce response accelerations and displacements comparing with those of passive systems, although they had a problem that the dampers might fail to generate damping forces due to malfunctions in strong earthquakes. To solve the problem, a new type of controllable friction damper with a fail-safe mechanism was developed in this study. For the damper, piezoelectric actuators were used to make the mechanism simple. The actuators are compact, and can make quick responses and produce large forces. Simulations and excitation tests were carried out for the semi-active system using the friction dampers, showing good performance in reduction of response acceleration and displacement together with higher reliability comparing with systems using conventional friction dampers.