Seismic Response Analysis Of Nuclear Island Building Considering Fluid-structure Interaction Effect Of Gravity Cooling Water Tank

The constructions of nuclear power plants are developed rapidly in China since twenty-first century.“Large advanced Pressurized Water Reactor?PWR?and High Temperature Gas-cooled Reactor?HTGR?nuclear power plant”is established as“National Science and Technology Major Project”,public safety is recommended as important research field,monitoring and defense are recommended as priority themes.Earthquake is one of the external threats which could influence the safe operation of nuclear power plants,and adverse effect may be brought directly or indirectly.Compared with the traditional nuclear power plants,passive idea is introduced into new PWR nuclear power plants.As one important component of passive containment cooling system?PCS?,gravity cooling water tank which has high position and large mass is at the top of shield building.So the fluid-structure interaction?FSI?effect between water and tank should be considered.Different from common high-rise buildings,the nuclear island building has large rigidity,and there is not a conclusion whether FSI effect could reduce the seismic response of nuclear island building.Aiming at the above backgrounds and problems,one new PWR nuclear island building was chosen as the research object.Considering the FSI effect of gravity cooling water tank,shaking table test of water tank model,structural dynamic characteristics,verification of numerical method,influence of FSI effect and simplified model of FSI effect were studied in detail and some results were got.The main research works of this paper are as follows:1.A 1/16 scaled model of gravity cooling water tank was designed and the shaking table test was done.The dynamic response of structure,hydrodynamic pressure time histories and attenuation data of wave height were recorded.The stiffness characteristic of structure was evaluated.The sloshing frequencies and damping ratio were identified.The degree of anastomosis between test results and standards was verified.2.According to the water tank model,numerical model was established by finite element software.Based on the potential-based fluid element and interface element,the FSI effect was simulated and modal analysis and seismic response analysis were done.The sloshing frequencies were calculated by theoretical formula and the reasonableness of equivalent method was verified.After comparing the hydrodynamic pressure time histories between numerical results and test data,the reasonableness and accuracy of numerical method were verified.3.The codes for seismic design of nuclear power plants in China and United States were compared.There were some differences in fortification objects,peak accelerations,control points of design response spectra and response spectra values.4.Modal analyses and seismic response analyses of two models which considering FSI effect or not were done.Natural frequencies of nuclear island building were compared.The acceleration responses,floor response spectra and effective stresses of reference points at water tank,shield building and auxiliary building were analyzed.The influence of FSI effect was studied.5.Based on Housner model,the simplified model which can be used for three direction seismic response analyses was derived and the related parameters were calculated.Modal analyses and seismic response analyses of model considering FSI effect and simplified model were done.The relative errors of 1^st sloshing frequency and natural frequencies were compared.The degree of anastomosis in acceleration responses,floor response spectra and effective stresses between two models were studied and the application scope of simplified model was investigated.