DYNAMIC RESPONSES OF BASE-ISOLATED STRUCTURE UNDER THE NEAR-FAULT HORIZONTAL-VERTICAL SEISMIC ACTION

During the application process of base-isolated technology，which is a generally acknowledged measure to resist the earthquake action and reduce the loss of building structure. But the near-fault seismic action with a strong shock is not taken into account usually，and the vertical component is less especially. Some earthquake acceleration records，which include the complete horizontal and vertical components from Chi-Chi Earthquake in Taiwan，are selected and divided into three types，near-fault，far-field and non-pulse seismic inputs. The dynamic responses of base-isolated structures and the states of base-isolated supports are analyzed under the horizontal and vertical motivations of those records simultaneously. The results show that the impulsive near--fault earthquakes impact on the medium and long-period base-isolated structures strongly. However the maximum velocity-pulse period of the seismic records do not control the dynamic responses of base-isolated structures absolutely. The seismic vertical component influences the horizontal responses of structures slightly. But base-isolated supports can be in the unsafe tension state under the pulse near-fault earthquake action，and stronger apparently than that under the non-pulse one.