Research On The Reasonable Value Of Elastic-story-Drift Limit Under Wind Load

To ensure that structures are in a state of elasticity and non-structural components are in good condition,current codes adopt measures to control the inter-story drift of structures under horizontal loads.With increasing height of buildings or basic wind pressure comes that,the wind loads gradually controls the calculation of structural behaviors.The inter-story drift limit under wind loads restricts the structural stiffness,and impacts on the economic efficiency.Highrise or super high-rise buildings worldwide are still safe and serviceable as for various interstory drift limits of different national(regional)standards,suggesting that these limits all satisfy the relevant requirements.However,current codes of different nations(regions)have great divergences in the degree of controlling the inter-story drift under wind loads.For the purpose of researching the rationality of elastic inter-story drift limit under wind loads in Chinese codes,this dissertation analyzes different codes of China,Europe,the United States,Australia/New Zealand,Japan,China Taiwan,and China Hong Kong,by combining both mathematic and computational models.The research contents and results are as follows:(1)Simplify the calculation of wind loads and establish mathematical models according to these seven national(regional)standards.Define an inter-story drift limit ratio to reflect the degree of controlling the limit in different national(regional)standards.Design computational models of frame,frame-shear,frame-tube,and shear wall structures,and afterwards,adopt the relevant standards of the seven nationals(regions),to analyze the computational models based on unified basic wind velocity and site type.The results show that,the mathematical models can accurately reflect the structural deformation patterns and precisely predict the relationship of the inter-story drift limit ratio of the seven nations(regions).In addition,the Chinese codes are more stringent on the control of the inter-story drift under wind loads for structures with shear walls as the main vertical components.(2)Chinese codes are also applicable to Hong Kong,therefore,Chinese codes and Hong Kong standards are used to analyze the computational models respectively.The results show that,the Chinese codes is more stringent than the Hong Kong standards,in terms of specifying the inter-story drift limit under wind loads for structures with shear walls as the main vertical components.(3)According to the results,it is suggested that the elastic inter-story drift limit under wind loads should be taken as 1/500,which are identical for different structure types or structure height.To obtain the influence of the inter-story drift on the economy,the maximum inter-story drift of a real construction project was adjusted from 1/600 to 1/1000,and it is indicated that,with decreasing the inter-story drift,the use of reinforcing steel raises,while the use of concrete and the total cost reduce.