Seismic Analysis Of Ultra-high-rise Frame-core Tube Two-way Bias Structures

With the development of ultra-high-rise buildings with greater height,more complex structural arrangement and more functional requirements,influenced by building function,body shape and vertical traffic,some cores are gradually set on one side of the structural plane in the frame-core structural system,and under the horizontal and vertical loads.The overall forces performance of these structure are different from the usual frame-core structures.The relevant provisions of the current national codes and regulations are exceeded.This paper focuses on the force performances of frame-core tube two-way bias offset supertall structures.Numerical analysis methods are used for such core tube two-way bias offset structures to summarize the relationship between the force characteristics of the structure and the different degrees of core bi-directional offset under vertical and horizontal loads.After reviewing the research results on frame-core structure both at home and abroad,this paper focused on the current engineering situation of core offset,combined with domestic engineering examples and research.With Yingjianke(YJK),ETABS and Perform-3D finite element analysis softwares.We carried out small to medium to large seismic analysis of some ultra-high-rise frame-core tube two-way bias structures as the research object.The study was carried out to investigate the force characteristics of ultra-high-rise frame-core tube two-way bias structures,to analyze the variation laws of structural properties such as torsional effects and torsional period ratios with the degree of core offsets,and to further propose corresponding strengthening measures to reduce the influence of core offsets.The main research contents are as follows:First,three-dimensional spatial models were established by using YJK and ETABS finite element analysis softwares to study ultra-high-rise frame-core tube two-way bias structure with a seismic intensity of 7 degrees and a structure height of 169.90 m.The vibration decomposition reaction spectrum method was used to analyze the structure in elasticity under multiple earthquakes and to compare various seismic performance indexes of the structure;for the purpose of verifying the structural performance under the effect of medium earthquakes In order to verify the performance of the structure under medium earthquakes,the structural analysis was carried out,and the elasticity and unyielding of the structure under medium earthquakes were verified and compared with the results under small earthquakes.The elastic time analysis method was used to supplement the vibro-decomposition reaction spectrum method and compare the seismic performance indexes.Secondly,in order to study the force characteristics of frame-core bi-directional offset supertall structure,numerical analysis method is used to establish a total of 36 computational models for core centering,uni-directional offset and bi-directional offset by ETBAS according to different offset degrees and structure heights,and analyze the torsional displacement ratio,torsional period ratio,torsional period ratio of the structure with core unidirectional and bi-directional offset under horizontal load and vertical load are summarized,The changes of structural properties such as horizontal deformation with the degree of offset and the height of the structure are summarized.Finally,in order to further study the force characteristics and member performance of the ultra-high-rise frame-core tube two-way bias structure under the action of rare earthquakes,the finite element software Perform-3D is used to perform dynamic elasto-plastic time history analysis on the ultra-high-rise frame-core tube two-way bias structure engineering example,and analyze the shear forces,top displacement,inter-story drift angle and member performances under the action of rare earthquakes.According to the force characteristics and member performance,we can take effective strengthening measures for this kind of core offset ultra-high-rise structure purposely.The results of the study show that the cores are bidirectionally biased.The research results show that the force characteristics of the core bi-directional offset supertall structure under horizontal and vertical loads are as follows: the torsional displacement ratio of the structure is linearly related to the degree of barrel offset,and the increase of the barrel offset will intensify the torsional effect of the structure;when the height of the structure is small,the greater the degree of barrel offset,the greater the torsional period ratio of the structure,but when the height of the structure is high,the relationship between the degree of barrel offset and the torsional period ratio of the structure is not obvious.The relationship between the degree of cylinder bias and the torsional cycle ratio of the structure is very weak when the height of the structure is high,which shows that the height of the structure has a greater influence on the torsional cycle ratio of the core offset super tall structure.