RESPONSE OF CONTAINMENT STRUCTURE WITH NONLINEAR SOIL-STRUCTURE INTERACTION

Abstract

Design of critical facilities such as nuclear power plant requires an accurate evaluation of seismic demands, as any failure of these facilities poses huge threat to the community. Design complexity of these structures enforces the inevitability of a robust 3D modeling and the soil-foundation interface. This report includes past research related to effect of soil structure interaction especially on nuclear facilities. Analytical model of NPP along with the underlying soil presented here. Finite element model of nuclear structure and soil surrounding to it is done using F.E software Abaqus. For superstructure, concrete damage plasticity model has been adopted. Concrete damage plasticity model has been validated with three point beam problem. Reinforcements in superstructure are modeled as truss elements and embedded in concrete with the assumption of full bond with surrounding concrete. Soil is modeled as an elastoplastic material using Mohr-Coulomb failure criteria. To avoid reflection of waves back into problem domain absorbing boundaries are used at the finite soil boundaries. Dashpot elements are used as absorbing boundaries which eliminates box effect and act as quite boundaries. Mesh convergence tests have been performed before adopting mesh of the structure and soil for analysis. Change in fundamental time period of structure after introduction of soil has been observed. Also, response of nuclear containment structure in terms of crown acceleration and displacement have been noted for fixed base, linear SSI and nonlinear SSI. Three component nonlinear time history analysis has been performed to compare with one component time history analysis. Damage study of superstructure has also been performed.