Shaking table test of 4-DOF base-isolated structure with variable oil damper

A new device is proposed for controlling seismic displacement of a base-isolated building structure by means of a variable oil damper (VOD). This damper provides large damping to reduce the response displacement of the base-isolation layer in severe or extreme seismic events, whereas it provides small damping to reduce the response acceleration of the superstructure in moderate seismic events. Through shaking table tests, it is shown that the VOD can effectively reduce the maximum displacement of the base-isolation layer without increasing the damper force. Comparisons on analytical and experimental results verified the validity of the proposed analysis method.