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.
