Seismic Performance Analysis Of Frame Core Tube Structure With Buckling Restrained Braces In Super High-rise Duilding

The frame core tube structure with strengthened stories in super high-rise building is able to increase the lateral stiffness of the structure,however,it leads to mutation of internal force.If it is removed,the structure can not meet the requirements of the specification on the inter story drift angle.The buckling restrained brace has the advantages of good energy dissipation capacity and stable bearing capacity,which can be used to remove the lateral stiffness of the whole structure.Therefore,in this thesis,the strengthened layer in the original structure is replaced by the buckling restrained brace,and the internal force distribution is changed and the mutation is relieved when the horizontal lateral displacement of the structure meets the requirements of the specification.Firstly,this thesis taking the super high-rise building with a frame core as the background,this thesis compares the structure characteristics of the stress and deformation after removing original model strengthened stories.Secondly,the design procedure of buckling restrained braces and the calculation method of relevant parameters are introduced.In super high-rise frame core tube structure,for the study of BRB arrangemen in the whole facade's affection of force and deformation,it sides by side span,middle span and cross arrangement.Based on the finite element method,the numerical simulation is carried out by using SAP2000 software.The response spectrum method is used to investigate the periodic,mass,stiffness ratio,seismic shear force,moment of beam,column axial force and proportion of overturning moment of frame column to total overturning moment under different layout schemes of BRB.Besides,the elastic dynamic time history analysis method is used to discuss the characteristics of internal force and deformation under different layout schemes of BRB.It studies layer displacement,inter-story displacement angle,floor shear and base shear time history curve of structure.The design bearing capacity of buckling restrained brace is checked.Finally,the nonlinear constitutive equations and parameters of SAP2000 are defined,and the elastic-plastic time history analysis of the BRB under cross span is presented.It investigats inter-story displacement angle and peak displacement time curve of the structure under different seismic waves.The elastic and elastic-plastic base shear time history curve of structure under earthquake are compared.The results show that the natural vibration period is slightly longer,the lateral stiffness ratio is uniform,the structural quality is obviously reduced,the reduction rate is 7.3%,and the material consumption is saved after removing strengthened stories and adding BRB;The maximum reduction rate of internal force mutation amplitude can reach 35.4%;Under small earthquake,the cross span can reduce the layer displacement more effectively,and the maximum decrease is 20.2%,which shows that the continuity of the BRB throughout longitudinal direction,the better the effect of layer displacement control;Under the rare earthquake,the inter-story displacement angle can meet the requirements of the code,and the base shear force is less than the base shear force of the elastic model under the rare earthquake,the maximum reduction ratio is as high as 25.4%,which shows that the BRB can reduce the seismic response.Through the optimization of the original structure,not only to overcome mutation of internal force and appearance of seismic weak floors that are prevalent in today's super high-rise structure,but also meet the specification of the inter-story displacement angle limit.It provides some reference value for the structural design of this kind of practical engineering.