| With the rapid development of economy domestically and overseas,and the rapid increase of urban population in all regions,the building structures are getting higher.So the control of the shear-weight ratio is becoming more difficult.The shear-weight ratio is one of the important design indexes of the overall performance of high-rise building structures,which mainly controls the minimum earthquake force of each floor so as to ensure structural safety.Therefore,it is significant for the code to stipulate the minimum shear-weight ratio.Many scholars have analyzed the shear-weight ratio of super high-rise buildings.It is very popular to study the control of the shear-weight ratio and its influencing factors.In this paper,the requirements for shear-weight ratio in China and overseas are compared.The influence of site classification on minimalshear-weight ratio is not considered in China's code.In addition,some studies have shown that the basic natural vibration period,vibration mode mass participation coefficient and damping ratio also have certain effects on the shear-weight ratio of the structure.The model A was established based on a RC core tube + outer frame + ring truss structure of a super high rise building in Shanxi.The response spectrum analysis of the model A was conducted by two software,Midas Gen and SATWE,and the influence factors of the shear-weight ratio were discussed.In Midas Gen software,the model A was used as the original model.Under the condition that the outer wall area of the core wall of the structure model was constant,the elastoplastic contrast model B was established by changing the outer wall arrangement.The model C was established by decreasing the thickness of the outer wall in the core tube of the model B,and.The response spectrum analysis,elastic time history analysis and elastoplastic time history analysis of the model were carried out.The conclusions are given below:(1)By changing the period reduction coefficient,the modal mass participation coefficient,the site category and the damping ratio of the model A,the response spectrum analysis was carried out.When other factors are constant,the smaller the period reduction coefficient is,the larger the shear-weight ratio is;the greater the modal mass participation coefficient is,the greater the shear-weight ratio is,but the change is notobvious;the softer the site soil is,the larger shear-weight ratio is,indicating that the same building structure is not easy to meet the shear-weight ratio requirement in better site conditions,and it is obvious that the minimal shear-weight ratio limit of the code is not reasonable;the larger the damping ratio is,the smaller the shear-weight ratio is;and the fundamental vibration period and the site category of the structure have great influence on the shear-weight ratio.(2)The results of the response spectrum analysis of three models show that the minimal shear-weight ratio of the model B and the model C is the same,which is closer to the limit of the minimal shear-weight ratio stipulated in the code.It is considered that the simple adjustment of the structural stiffness does not necessarily achieve the purpose of adjusting the shear-weight ratio.The story drift of model A and model C were greater and the material performance exerted more.(3)The results of the elastic time history analysis of the A and B models show that,compared with the response spectrum results,the corresponding base shear of each seismic wave is more than its 65%,and the average value of the corresponding base shear of three waves is more than its 80%,which satisfies the 1/800 limit value of the elastic story drift.The results of the elastoplastic time history analysis of three models show that the elastoplastic story drift is in conformity with the 1/100 limit value of the code.The structure of the model has good ductility to meet theaseismic requirements of large earthquakes.Considering the shear-weight ratio and story drift,the model C is better than model A and model B. |
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