Study On Seismic Performance Of A New Disperse Core Tubes Structure With Energy Dissipating Braces

As the core part of a super high-rise building,the core tube can resist most of the shear force and nearly half of the overturning moment generated by horizontal forces in the building.If crush failure or shear failure occurs to the base walls of the core tube in an earthquake,causing severe damage to the base wall columns of the core tube,the restoration of the columns will be very difficult.Besides,as modern high-rise buildings get ever higher,once the base wall columns of the core tube get damaged,the incalculable loss will be incurred.For this reason,it's necessary to improve the shear walls of the core tube so as to curb damage to the walls.To fundamentally solve the problem of severe damage to the walls because of excessively concentrated rigidity in the core tube,this paper combines other scholars' research approaches on improving the shear walls of the core tube,and systematically comes up with a new disperse core tubes structure with energy dissipating braces.The core tube is separated into multiple disperse tubes to make the rigidity of the core tube less concentrated;framed beams and energy dissipating buckling-restrained braces are used to connect the disperse tubes,and CFST embedded columns are deployed at tube corners to guarantee lateral rigidity of the structure.Buckling-restrained braces can dissipate earthquake energy,protecting the core tube walls from too much damage,and meanwhile,they can be replaced quickly and easily after an earthquake,making structural restoration after an earthquake no longer a daunting task.This paper takes a super high-rise frame-tube structure with a regular plane layout as its object of research,makes changes to the plane layout,and creates a new disperse core tubes structure with energy dissipating braces.Then,the earthquake-resistant performance of the structure is studied from aspects including vertex displacement,inter-floor displacement angle,base shear,damage to core tube material,earthquake energy dissipation,etc.Finally,to more comprehensively study the earthquake resistant performance of the new disperse core tubes structure with energy dissipating braces under the influence of key parameters,changes are made to the yield strength,lateral rigidity ratio and other key parameters to conduct elasto-plastic time history analysis on the new structure,study the distribution pattern of dissipated hysteretic energy between structural members and the dissipated hysteretic energy distribution of each member along the vertical direction,and determine the key design parameters of the new structure as well as each parameter' rational value scope,which will provide a theoretical basis for design of the new structure.The research work and conclusions of this paper cover the following aspects:(1)In order to study the difference between the earthquake resistant performances of the new structure and the common reinforced concrete frame-tube structure,a super high-rise frame-tube structure with a regular plane layout is used as the object of research,and 7 seismic waves are selected based on code response spectra to conduct nonlinear time history analysis on the two structures.Then,comparative study on the earthquake resistant performances of the two structures is carried out from aspects including vertex displacement,base shear,inter-floor displacement angle,damage to core tube material,etc.The results show that the overall performance of the new disperse core tubes structure with energy dissipating braces is not significantly reduced,and the force of the wall bottom limb is improved.The shear strain of the shear wall concrete and the tensile strain of the steel reinforcement material are greatly reduced.The damage of the cylinder material has been optimized,and it has been verified that the energy-dissipation support-dispersed core tube structure system has better seismic performance than the common frame-core tube.(2)To further study the earthquake-resistant performance of the new disperse core tubes structure under strong earthquakes,changes are made to peak ground acceleration and longperiod seismic waves of varied spectral characteristics are selected to conduct analysis.Research work is not limited to aspects including vertex displacement,base shear,inter-floor displacement angle,damage to core tube material,etc.,but also covers evaluation of the structure's earthquake-resistant performance through seismic oscillation energy dissipation and structural members' energy dissipation distribution.The conclusions are as follows: the new disperse core tubes structure with energy dissipating braces is under slight or slight damage to core-reinforced concrete reinforcement materials under seismic action that exceeds fortification intensity,but damage to the concrete reinforcement material of core tubes is without exception slight or insignificant,and no severe damage beyond repair occurs.Under long-period seismic conditions,the new disperse core tubes structure's reinforcement materials does not reach serious damage,the earthquake-resistant performance of the new structure improves substantially than that of the common frame-tube structure.(3)In order to study the influence of critical performance parameters of decentralized cores with energy dissipation on the hysteretic energy damage of structures,models are created through changes made to key parameters including yield strength of buckling-restrained braces,lateral rigidity ratio of braces,shear wall thickness of core tubes to study the distribution proportion of each energy item in the structure and the influence of key parameters on the dissipated hysteretic energy ratio of the structure.The transmission and distribution patterns of dissipated hysteretic energy in each structural member as well as the distribution pattern along the vertical direction are analyzed.For the purpose of reducing damage to the core tube walls,it's recommended the ratio of the anti-buckling support to the core tube should not be too large when the structural rigidity is ensured.Low yield material should be selected as the core material for the buckling-restrained support.