Recently, 3 dimensional FEM is applied to the earthquake response analysis of the soil-structure interaction system. The more the number of the elements of the interaction system is used, the larger the calculative load becomes. In the previous papers, the time domain energy transmitting boundary for 3 dimensional problem was proposed to improve the efficiency of calculation. In this paper, applicability of the time domain energy transmitting boundary to the 3 dimensional FEM of the nuclear power plant building is analyzed. First, applicability of the time domain energy transmitting boundary to the rigid soil is confirmed by comparison with the viscous boundary. Next, calculative load reduction method is proposed by using the time domain energy transmitting boundary and analyzed the accuracy of the proposed method. Finally, by using the proposed method, applicability of the time domain energy transmitting boundary to 3 dimensional FEM building is analyzed with the effect of the reduction of the calculative load.
