Study On Dynamic Analysis Models And Seismic Performance Of Story Isolation Structure

Seismic isolation technology is one of the most efficient seismic methods for building structures.Fully understanding the response characteristics of story isolation structure under earthquake action is of great significance to the design and application of isolation structure.It is also an essential link in the process of realizing earthquake science and technology innovation,implementing "resilient urban and rural" plan,and improving the seismic disaster resilience of urban and rural areas.Because of the different location of the isolation layer,the whole structure is divided into three parts.the superstructure and the substructure and the isolation layer,which is weak in the structure due to the smaller horizontal stiffness.Compared with the base isolated structure,the story isolation structure does not simply move the isolation layer up,but the deformation form and working mechanism of its superstructure and substructure are also different due to the different isolation layer positions.Therefore,in this paper,the dynamic analysis models and seismic response characteristics of story isolation structure are studied as follows:（1）Based on assumptions,a distributed parameter system model of story isolation structure is established,and the calculation method of structures response of the model is obtained by mode superposition method.On this basis,taking a 10-story made by ETABS structure as an example,different dynamic analysis models of story isolation structure are compared.The results show that the particle system model can not effectively calculate the response of upper layer of the structure,and the accuracy of the shear model is lower than that of the distributed parameter system model.The distributed parameter model based on the finite element method is the best method to calculate and analyze the structure response with both accuracy and efficiency.（2）The influence of different parameters of story isolation structure on the structural response is studied,based on the distributed parameter system model.The results show that.when the design is unreasonable,the response of the substructure of story isolation structure is amplified,and increasing the mass of the superstructure will effectively reduce the response of the substructure;when the isolation layer is located in different positions,the optimal mass ratio of the structure increases linearly with the location of the isolation layer.At the same time,the first-order sensitivity of structural response to random parameters is also analyzed,and it is found that the substructures are coupled with each other under random earthquake action.The sensitivity of structural response to random parameters runs as the rule of"damping ratio of isolation layer>mass>stiffness",while the responses of the isolation layer is the most sensitive to the change of parameters,and the response of other substructures shows different variation rules.（3）The nonlinear response characteristics of story isolation structure under extremely rare earthquake are studied.The results show that:under the strong earthquake excitation,each substructure obviously enters the plastic state,the maximum inter story displacement of the structure occurs in the isolation layer,and the deformation of the isolation layer lags behind the input obviously,even if the earthquake stops,the isolation bearing will continue to deform or even destroy,causing damage to the structural safety.With the increase of the isolation layer position,the maximum interlayer displacement angle of the substructure decreases;When the structure is in the form of lower isolation,the probability of the maximum interlayer displacement angle of the top layer is the largest;When the structure is in the form of upper isolation,the maximum inter story displacement angle occurs in the substructure,so the strength of the top layer and the bottom layer of the structure should be paid special attention in the design of story isolation structure.