論文ID: 24-00462
This study investigates the effects of the Fluid-Structure-Soil Interaction (FSSI) on the seismic responses of a deeply embedded nuclear facility with large water pools under severe earthquakes. This paper presents an efficient seismic analysis method for considering FSSI using 3D FEM for deeply embedded typical RC (Reinforced Concrete) shear wall nuclear buildings. In the proposed method, the commercial SSI analysis software, ACS SASSI was used with Option AA-F, which treats ANSYS fluid element FLUID80 dynamic matrices in ACS SASSI environment. Using the proposed method, it was confirmed that large pool water in the building provides significant local deformation of the pool walls, while the effects on other parts of the structure are almost negligible from engineering point of view. To capture the structure behavior during severe earthquakes, the nonlinear behavior of the structure was taken into account. The proposed FSSI method was applied using the ACS SASSI NQA Option NON software. To model the RC walls nonlinear behavior, their nonlinear back-bone curves (BBCs) were computed using both Japanese and US standards. Then, the nonlinear analysis SSI responses with both standards were compared. It was confirmed that the nonlinear structure behavior produced a visible shift of the ISRS (In-Structure Response Spectra) peak responses to the lower frequencies in comparison with the response of linear analysis. It was also confirmed that the amplification of ISRS in nonlinear analyses comparing with elastic linear analyses are strongly influenced by the frequency content of in the in-column input motion at foundation level. Consequently, it was shown that differences between the formulations and requirements in the two standards could affect seismic responses more or less depending on the frequency content of in-column input motion, structure dynamics, and nonlinear modeling of structural behavior.
