Floor Response Spectrum Analysis Of Nuclear Power Plant Structures Based On Three-dimensional Solid Model

In this paper, against the nuclear power plant structure, the influence of soil parameters on the floor response spectra is investigated by considering soil-structure interaction (SSI), and two models, namely complicated three-dimensional solid Finite Element (FE) model and simple lumped mass model, are founded,then respectively carry through numerical analysis under two conditions(with SSI effect and without),this paper may provide a referenced approach to evaluate the seismic safety of nuclear power plant structures,at the same time,via breadthwise comparing two models'calculated results under the same condition,bring forward some advice for how to establish logical numerical model of the nuclear power plant structure. The main contents as follows:(1)Based on the linear elasticity analytics and deterministic theoretics(without considering material randomicity)to account the results,the substructure(impedance)method is employed to consider the SSI effects.(2)According to the structural design of the reactor building of Ling-ao nuclear power station, the two analytical models, three-dimensional FE model and lumped mass model, are constructed using the universal FE software ANSYS as basic analysis tool. The seismic response analysis on each model is conducted under the conditions with SSI effects and without respectively. Just the spring and damping elements are set to simulate SSI effects in ANSYS program.(3)Artifical wave LBNS is selected as the ground motion input. For each case, the outputs from the analysis are the nodal time history displacements and then the resultant accelerations are calculated. These accelerations are input to a computer code that calculates the floor acceleration response spectra by Fast Fourier Transform (FFT). After that,the results from the two different models are compared.The comparison indicates that considering SSI effects can affect the seismic response of structures remarkably, and it is safer to using the lumped mass model than the three-dimensional FE model.