Estimation of vibration characteristics of nuclear facilities based on seismic observation records

Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*; Nishida, Akemi  ; Kawata, Manabu; Iigaki, Kazuhiko 

Several large-scale earthquakes have occurred, such as the Niigataken Chuetsu-oki Earthquake in 2007 and the 2011 off-the-Pacific coast of Tohoku Earthquake. Therefore, a three-dimensional (3D) finite element model to evaluate the local response of the reactor building is currently being developed for seismic response analysis. In order to refine the 3D finite element model, it is important to verify the correspondence to the seismic observation behaviors. In this study, the authors analyze the basic response characteristics, such as the natural frequencies and modes of the reactor building, and evaluate the effects of the amplitude of the seismic excitation on the response characteristics based on seismic observation records. This is done to clarify the behavior of a reactor building during earthquakes. These analyses will assist in quantitatively evaluating the correlation between the natural frequency of the building and the amplitude of the seismic excitation. Furthermore, the ratios of rotational displacement and displacement caused by building deformation for natural modes are discussed.