Dynamic characteristics of base-isolated reactor building subjected to various types of travelling waves

Studies on the base isolation systems applied to nuclear reactor building have been reported recently ( Kunar 1979 ). In the isolation systems, laminated elastomer bearing pads (LEBPs) are widely used to decrease the responses of structure by lengthening the natural period ( Jolivet 1977 ). Therefore, the characteristics of input earthquake motions should be studied in the seismic design of isolated structures. Most of the devices having LEBPs are effectively operated only for the horizontal motion, but they are ineffective for the vertical or rocking motions. For the structure subjected to seismic waves with phase difference, such as obliquely incident waves or surface waves, the rocking and torsional movements of the structure are additionally produced. However, there have been few studies on the responses of the structure with the base isolation systems subjected to the motion with phase difference ( Richili 1981 , Wolf 1983 ).