Seismic Research Of Primary-secondary Coupled System With Equipment Base Isolation

The seismic safety of industrial equipment is related to the safety of people's life and the continuity of production after the earthquake.In order to reduce the damage of the equipment,many industrial equipments use base isolation technology.The practice shows that the base isolation technology can reduce the damage of industrial equipment effectively.The structure and the industrial equipment which placed on the floor form a primary-secondary coupled system.The isolation device makes the dynamic interaction between main structure and substructure more complexity.The comprehensive analysis of primary-secondary coupled system with equipment base isolation under earthquake,which has important theoretical significance and engineering application value for the seismic design of the structure and the industrial equipment.First,mechanical models for series double degrees and multi degrees of freedom are established,which are based on primary-secondary coupled system with equipment base isolation.The dynamic equilibrium equation is given and solved.The effects of frequency ratio,mass ratio and damping ratio of isolation layer are analyzed by control variable method.The variance of displacement,velocity and acceleration of the coupling system are optimized,which can reduce the dynamic response of the coupled system.Last,modal analysis of primary-secondary coupled system with equipment base isolation or not are performed with SAP2000,and the influence of the stiffness of isolation layer on the natural vibration period of the composite system is analyzed.The article selects three seismic waves to do linear time-history analysis and nonlinear time-history analysis,which according to the characteristics of earthquake accelerationresponse spectrum and the basic natural vibration period.The internal force,deformation,displacement of coupled system are studied,and the influence of the damping ratio of the isolation layer on the horizontal displacement of the coupling system is analyzed.Research shows that the mass ratio,the frequency ratio and the damping ratio of the isolation layer are the main parameters that affect the seismic response of the system,among them,the influence of the mass ratio is small and the regularity is not obvious.The response of the whole system can be effectively controlled when the frequency ratio of the main structure and the substructures between 0.50~0.60 and the mass ratio is relatively small.The first nine order natural vibration period of primary-secondary coupled system with equipment base isolation will increase.When reducing the stiffness of isolation layer,the first three order natural vibration period of coupled system increases significantly,but from the beginning of the four period almost unchanged.Under the action of frequent earthquakes and rare earthquakes,the equipment with base isolation has little effect on base shear,floor acceleration and story displacement of the main structure,but it can obviously reduce the horizontal acceleration and increase the displacement of substructure.When increasing the damping ratio of the base isolation layer,the displacement of the main structure is very small,the displacement of substructure is more obvious,and the decreasing trend is linearly.The research work and conclusions of this paper have some reference value for the design of industrial equipment.