Study On The Influence Of Steel Mega Frame Seismic Behavior Owing To Sub-Truss In Subordinate Structure

With the continuous development of high-rise buildings,the traditional forms of anti-side force structure can not meet the multi-function of high-rise buildings,as well as integrated use of building space of high-rise buildings' requirements.Mega-frame structure as a new,highly efficient mechanical system,is the high-level understanding and development of the traditional sense of the concept of the structure of framework.This system meets multiple serve requirements of high-rise buildings.This paper presents the characteristics of mega-frame structural system and summarizes study and recent application of the mega-frame structural system.Based on that,the author utilizes two categories of supports in mega-frame structural system.One is steel support,the other is the viscous damping support.The author analyzes the consideration of sub-structure and sub-structure with adding supports which affect properties of seismic resistance of mega-frame steel structural system.Finite element analysis software SAP2000 is used to establish seven models of mega-frame steel structure.After analyzing static performance and dynamic response analysis of models as well as addressing elastic-plastic destruction behaviors of 4 of those models when under 8 degree earthquake,conclusion is showed below:(1) The characteristics of mega-frame structural system are that framework in the structure system comprises main frame and sub-frame.The sub-frame only supports vertical loading of several stories and deliver it to main frame.The main frame support the majority of anti-overturning moment and shear force.(2) At the aspect of static performance of models,the structural advantages of sub-frame of mega-frame steel structure with adding steel support are obvious.Meanwhile,lateral rigidity of mega-frame steel structure is enhanced significantly and the lateral displacement and story drift angle of the structure under wind load is control efficiently as well as the reduction of mutation value of vertical internal forces of the structure.It can be clearly seen that properties of static performance of mega-frame steel structure adding supports is better than the one with non-supports.(3) In this paper,three typical seismic waves are chose of which two are natural wave (EL-centro wave and the Taft-wave) and one is an artificial wave(Lanzhou-wave 3,â…¡-type sites(LAN4-2) to be conducted time-history analysis under 8 degree earthquake.According to construction seismic resistance criteria,top-level lateral displacement and story drift angle of four models under earthquake meet requirements,top-level lateral displacement and story drift angle of three models adding supports are much smaller than the one without supports. At the same time,reasonably locating supports can improve dynamic properties of the structural system. (4) When conducting elastic-plastic time-history analysis of models under 8 degree earthquake,analysis has shown the improvement of structural seismic resistance properties of the structural system without supporting and the structural system with different location of supporting.The results has showed that sub-frame with supports improves mechanism performance as well as yield orders of mega-frame structure suffering rare earthquake,and enhances relative stiffness of the structure.Sub-frame with supports not only reduce lateral displacement at top-level of mega-frame steel structure,but decreases maximum story drift angle.If the location of supports is proper,same amount of supports can have better influence on seismic resistance.(5) Sub-structure settings viscous damper support,the effect of structural damping significantly.Viscous damper supports inherit the advantages of steel support,reduce the deformation of the structure,overcome the shortcomings of the steel supports and decrease seismic response of mega-frame steel structure.Moreover,the support of viscous damper hysteresis curve of hysteretic loop is full,on behalf of many energy-consuming on the support of viscous damper damping effect.This paper shows that adding supports in sub-frame can strengthen the cooperation of main-structure and sub-structure.The supports to sub-frame can yield in the early stage under rare earthquake,which is the first defensive line of mega-frame steel structure against earthquake.Turing mega-beam and sub-frame from the first defensive line to the second one, can improve the whole capacity of seismic resistance.