Effect Of Superstructural Strength And Stiffness On Seismic Performance Of Isolated Frame Structures

The research on the existing isolated structure mainly focuses more on the isolation bearing,but less on the influence of the mechanical properties on the seismic performance of the whole isolated building.This paper designs isolated reinforced concrete frame structures that meet the requirements of the code.Based on this,the strength and stiffness of the isolated structure are sequentially increased.A total of 16 isolated structure models are established to study the strength,stiffness and at the same time,adjust the impact on the seismic performance of the isolated structure.In this paper,SAP2000 finite element software is used to adopt the Pushover analysis and dynamic time history analysis of the isolated model.The Pushover analysis selects the inverted triangle loading mode and the uniformly distributed loading mode,and studies the changes from the pushover curve,plastic hinge,and story dirft ratio.The impact of strength,stiffness,and both changes on the seismic performance of the isolated structure.For dynamic time history analysis,two sets of natural waves and one set of artificial waves are selected as seismic excitations to study the response of the superstructure’s bearing capacity and stiffness to the acceleration of the isolated frame,displacement response,interlayer shear force and energy dissipation ratio of the isolated support impact.The results of Pushover analysis and dynamic time history analysis of seismic isolation frame show:(1)The self-vibration period of the isolated structure surpasses the excellent period of the site,and the seismic performance is superior to the ordinary structure.(2)Increasing the strength can greatly reduce the degree of damage to the isolated structure.At the same time,as the strength becomes larger,the effect of reducing the degree of damage to the isolated structure decreases,that is,the effect of improving the seismic performance is weakened.However,increasing the strength has little effect on the acceleration,story drift ratio,inter-layer shear force,and energy consumption ratio of the isolated structure.(3)Increasing the stiffness has a significant effect on reducing the story drift ratio of the isolated structure,and improves the seismic performance of the isolated structure,especially the first and second floors.As the stiffness increases,the decrease in the story drift ratio decreases,that is,the new seismic the improvement effect is weakened;at the same time,increasing the stiffness has a significant impact on the acceleration of the isolated structure,the shear force between layers,and the energy consumption.(4)Increasing the strength and stiffness at the same time can greatly reduce the damage to the isolated structure and reduce the story dirft ratio.The effects on acceleration and shear between layers are similar to those when increasing the stiffness of the isolated structure.