Seismic Motion Incoherency Effects on Soil-Structure Interaction (SSI) and Structure-Soil-Structure Interaction (SSSI) Responses of Nuclear Structures for Different Soil Site Conditions

The paper investigates the effects of motion incoherency (3D random wave propagation) on seismic responses of nuclear structures with a focus on the seismic SSSI analysis.Basic theoretical aspects are briefly reviewed.Two NPP case studies are investigated.The incoherency effects are computed for both the single, standalone structure SSI models and the multiple structure SSSI models.The paper considers both rock and soil sites.The incoherent analyses were performed using stochastic simulation.Comparative SSI and SSSI responses include acceleration in-structure response spectra (ISRS), structural forces and moments.It is shown that the motion incoherency could amplify significantly SSSI effects for the soil sites.The seismic SSSI effects could impact significantly on the ISRS, soil pressures and bending moments in basement walls and slabs.