规范方法计算高层结构风振底部剪力的精确度研究

Accuracy of base shear force of tall building wind-induced vibration response produced by Chinese Load Code

中国荷载规范利用惯性风荷载(IWL)法来计算等效静力风荷载,由这样的等效静力风荷载可得到精确的1阶位移响应,但计算其他类型响应的背景分量往往误差较大,特别是结构底部剪力的背景分量。分别利用IWL法和随机振动理论计算出结构总动力响应(包括背景响应和共振响应),定义两者之比为IWL法精确度因子C。通过对因子C的研究,得到结论:(1)当结构的第1阶振型为弯曲型时,对绝大部分的钢结构和频率f1≤0.29Hz的钢混结构,由IWL法计算的总动力底部剪力精确度C≥95%;(2)当结构的第1阶振型为剪切型时,对f1≤0.7Hz的钢结构,由IWL法计算的总动力底部剪力精确度C≥95%;由IWL法计算的钢混结构总动力底部剪力精确度小于95%;(3)IWL法计算的总动力响应的精确度不满足要求时,需要进行修正,提供了对总动力底部剪力响应进行修正的方法。

The static equivalent wind load provided by the Chinese Load Code is equal to the inertial wind force called inertial wind load（IWL） method,which can produce the same first mode displacement response as the actual value,but cannot exactly produce other responses,especially the base shear force.The total dynamic responses（including background and resonant one） of structure are evaluated by IWL method and method of random vibration theory,respectively,and then accuracy factor of the IWL method,C is defined as the ratio of the two kinds of total dynamic responses.Studies on the factor C show that when the first mode of the structure is bending style,the accuracy factors of the base shear force are not less than 95% to almost steel structures and some reinforced concrete（RC） structures whose first natural frequency is not more than 0.29 Hz,when the first mode is shear style,the accuracy factors of the base shear force are not less than 95% to some steel structures whose first natural frequency is not more than 0.7Hz;but the accuracy factors of the base shear force are less than 95% to all of RC structures.When accuracy of the responses produced by IWL method is too low to meet the engineering requirements,the response values must be corrected and a method is suggested.