Applicability of equivalent linear three-dimensional FEM analysis of reactor buildings to the seismic response of a soil–structure interaction system

• The applicability of the equivalent linear analysis method for RC is evaluated. • 3D FEM analysis of RB with a small computational load considering SSI is performed. • The nonlinear and equivalent linear analysis results are compared. • The equivalent linear analysis shows good agreement with the nonlinear analysis. • We consider that the effectiveness of the equivalent linear analysis is confirmed. This paper evaluates the applicability of equivalent linear analysis of reinforced concrete, which uses frequency-independent complex damping with a small computational load, to the seismic design of nuclear power plant reactor buildings. To this end, a three-dimensional finite element method analysis of the soil–structure interaction focusing on nonlinear and equivalent linear seismic behavior of the building embedded in an ideally uniform soil condition (shear wave velocity Vs = 880 m/s) was performed for the Kashiwazaki–Kariwa Nuclear Power Plant Unit 7 reactor building. The equivalent linear analysis results correlated well with the nonlinear analysis results of the shear strain, acceleration, displacement, and acceleration response spectrum, demonstrating the effectiveness of the equivalent linear analysis method. Moreover, the equivalent linear analysis results were more conservative than those of nonlinear analysis using the material constitutive law in evaluating the shear strain of the external wall of the reactor building. From this observation, equivalent linear analysis tended to obtain a lower building stiffness than nonlinear analysis under the analysis conditions used in this paper. The equivalent linear analysis calculation results should be conservative in shear strain evaluation for seismic safety.