Comparative Study On Design Method Of Inter-story Isolated For Twin Tower Structures With Large Base

The theory and technology of inter-story isolation is an extension of base isolation application.The isolated layer is placed in the middle of the structure to control the seismic response of the structure.Extending the natural vibration period of the structure by using the flexible and isotropic characteristics of the horizontal direction of the support,increase structural damping,and the energy input to the upper part of the isolated layer is reduced.The main feature of the seismic isolation design method given in Chapter 12 of the “Code for Seismic Design of Buildings” GB50011-2010 is the partial design method.Establish a seismic isolation model,the elastic time history analysis is carried out according to the medium earthquake.Contrast the damping effect of the inter-story shear force and the overturning moment,determine the horizontal damping coefficient.The seismic influence coefficient is determined according to the horizontal damping coefficient and feed back to seismic structures,superstructure design using traditional seismic design methods.The main disadvantage of this design method is the design of seismic structures with the horizontal damping coefficient,and not to design the isolated structure directly.The newly compiled“Code for isolated Design of buildings”(draft for soliciting opinions)has made up for the above deficiencies.In this paper,a practical project in a certain area of Guangzhou-a twin tower structure with large base is researched.Seismic and isolation schemes are selected respectively,in the isolated scheme,the design method of chapter 12 of “Code for Seismic Design of Buildings” and the design method of isolated based on performance are analyzed and compared.Provide calculation basis for newly compiled “Code for isolated Design of buildings”(draft for soliciting opinions).The main work of this article is as follows:(1)Explained the background and significance of the research,in this paper,the present situation of the research on inter-story isolated and the application of inter-story isolatedstructure are summarized.the characteristics and application range of inter-story isolation system.(2)The equivalent analysis model of interstory isolated structures is introduced,general situation of engineering project and design flow of isolation.Determination of equivalent stiffness and damping ratio of isolation layer by iterative method.Taking the actual engineering project as an example,the paper compares three kinds of structures:designed by the horizontal damping coefficient method,the seismic isolation structure directly designed under the fortification earthquake and the aseismic structures.(3)Establishment of 3D finite element model for isolation design of two design schemes and comparison the effect of shock absorption.The dynamic time analysis method is used for earthquake,comparison of seismic and isolation structures to determine the damping coefficient.According to damping coefficient,the reinforcement design of the corresponding aseismic structure is carried out under frequent earthquakes.Consideration of equivalent damping ratio for isolated structures designed directly for medium earthquake and reinforcement design based on response Spectrum of Building isolated Design Code(draft for soliciting opinions)(4)Data extraction of seismic structure of frequent earthquake design,isolated structure of frequent earthquake and isolation structure designed by medium earthquake.Including:interlayer shear force,overturing moment,total steel,shear weight ratio,structural interlayer displacement angle(medium earthquakes,rare earthquakes,very rare earthquakes).ABAQUS software was used to analyze the structure of the above method.The maximum compressive stress and minimum tensile stress of the isolation bearing are studied and analyzed,displacement and deformation of isolation bearing and hysteresis curve of bearings,analysis of structural damage of three schemes.