Abstract
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. A new type of controllable friction damper with a fail-safe mechanism was developed to solve the problem 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. Excitation tests were carried out for the semi-active system using the friction dampers, therefore the seismic isolation effects and the relative displacement reduction effects improved in comparison with the passive seismic isolation system.
