Nonlinear Seismic Performance of Nuclear Structure with Soil–Structure Interaction

In the present study, the emphasis is made on the seismic performance of nuclear containment constructed on layered medium to dense silty sand soil considering the nonlinearity of the containment structure using the concrete damage plasticity (CDP) model and Drucker–Prager plastic model for soil. The finite element model is prepared using the ABAQUS. From the static pushover analysis, it is noticed that yielding force is reduced up to 8.37% and 2.37% in the case of with and without embedment, respectively, as compared to a fixed base. Furthermore, incremental dynamic analysis is performed for the motion range of 0.1 g to 0.6 g, corresponding to the fundamental frequency. For the dynamic analysis, Kelvin element is used at boundaries to incorporate the truncated soil mass. The results are shown in the form of base shear, base moment and displacement ductility, drift ratio, normalized peak settlement, and normalized peak foundation sliding. Moment demand is reduced up to 25.89% and 51.31% in the case of with and without embedment, respectively, as compared to a fixed base. Similarly, base shear demand is increased up to 21.85% in the case of with embedment. It may reduce up to 29.08% in the case of without embedment of foundation as compared to a fixed base. Drift demand of nuclear power plant (NPP) structure is increased up to 14.47% and 38.16% in the case of with and without embedment of foundation, respectively, as compared to a fixed base. In contrast, displacement ductility demand reduced up to 47.95% and 57.52% in the case of with and without embedment of foundation, respectively. Settlement demand is increased linearly in the case of with embedment with respect to ground motion intensity; however, it increases sharply for ground motion intensity > 0.3 g in the case of without embedment. The sliding demand of foundation increase with a low and fixed amount of sliding is examined in the condition of with embedment case; however, it rises steeply in the case of without embedment case, indicating that without considering the embedment effect may increase the design requirement and therefore lead to uneconomical designing. The effect of the CDP model shows the need to consider the nonlinearity of structure along with the nonlinearity of soil.