Seismic Performance Research And Comparative Study Of Different Vibration-mitigated Structures Of AP1000 Nuclear Power Plant

After 40 years of development,the concept of structural vibration control has been improved.By applying control devices to the structure,the seismic input energy is redistributed during the earthquake by the control device,which can effectively reduce the response of the structure,equipment and piping components under ground motion.Due to higher seismic requirement of the nuclear power plant,the integrity and safety of the structure should be guaranteed during earthquakes.So the structural vibration control technology is more of importance to the nuclear power plant.In this paper,the shielding factor of AP1000 nuclear power plant was taken as the research object.The seismic response analyses on AP1000 with TMD(Tuned Mass Damping)structure or base-isolated structure were carried out.While the parameters'optimization of the above structures was completed.The effects of seismic mitigation were discussed through comparative study on the above the structures.First,under the combination of equipment excitation and seismic excitation,based on the governing equation of structural vibration and the vibration reduction principle of conventional TMD structure,the parameter optimization of simplified models with or without main structure damping was studied by using fixed-point theory and particle swarm optimization(PSO).The large mass ratio TMD structure was designed combining with the conventional TMD structure and the characteristics of the shielding factor structure.By establishing the energy equilibrium equation and constructing Lyapunov equation of the large mass ratio TMD structure,parameter optimization of large mass ratio TMD structures was realized.Second,for base-isolated seismic structure,mechanical properties of isolation bearings and dampers were discussed.The hysteretic curve of vibration-isolated system was linearized effectively based on bilinear hysteretic model,and the hysteretic performance was analyzed based on hysteretic.Meanwhile the parameters of vibration-isolated system were optimized.At last,taking the shielding factor of AP1000 as the research object,the vibration-mitigated structures of the shielding factor were designed combining with passive containment cooling system.The finite element models of the shielding factor of AP1000 were established.The acceleration-time history?displacement-time history and base shear-time history on the models were obtained and support height of the large mass ratio TMD structure was optimized by numerical calculation.Compared with conventional TMD structure and base-isolated seismic structure on seismic responses,the large mass ratio TMD structure has better seismic performance.