Seismic Frigility Analysis Of Nuclear Power Plant Containment Considering Soil-structure Interaction

Containment is the last barrier to prevent leakage of the nuclear power plant, henceits seismic safety is of much important significance. This paper has analyzed the seismicfragility of the containment considering the soil-structure interaction with the aid of thefinite element analysis platform SAP2000and OpenSees.The completed work and mainachievements of this thesis are as follows:(1) On the base of fine model in numerical simulation, the existing restoring forcemodel of the containment has been improved and validated.The seismic fragilityanalysis has considered the soil-structure interaction(SSI).The soil lumped parametersmodel has accounted the the quality of the soil, which has a higher analysis precision.(2) Seismic fragility analysis based on the monte carlo method and responsesurface method is performed,respectively.Seismic fragility curve consideringsoil-structure interaction has been obtained. A mathematical method for proceding theresult from the nonlinear time history analysis is introduced, which has greatly reducedthe workload of monte carlo simulation.It is indicated by the analysis of the results offragility that the fragility depends on the selected damage index. In this paper, topdisplacement is suggested to be the damage index, for which has considered the positiveaffection of the plasticity of structure.(3) The seismic fragility analysis result based on the monte carlo method andresponse surface method coincide with each other through comparison, which verifiedthe validity of the model at the same time.The fundamental frequency of thecontainment is much high, corresponding to the up section of response spectrum.Hencethe response of the containment increase when considering the soil-structure interactionbecause of the decreased structural stiffness.So the SSI effect can not be ignored.