SEMI-ACTIVE CONTROL DESIGN OF HIGH-RISE SEISMIC ISOLATED BUILDING USING A SINGLE-MASS MODEL WITH TIME-VARYING DAMPING SWITCHING CONDITION APPLIED TO PREDOMINANT FREQUENCY OF EARTHQUAKE MOTION

Semi-active control by optimal control of two-stage variable damper determines variable damping by comparing the optimal control force obtained from structural response feedback with a threshold called damping switching condition. This study proposes a methods for varying the damping switching condition based on predominant frequency of earthquake motion. In designing the control, assuming the seismic isolated building is rigid and using a single-mass model allows design to consider only the primary natural mode. Applying the control designed using a single-mass model to a multi-mass model demonstrated superior control performance compared to conventional methods using a fixed damping switching condition.