超高层建筑风致振动的背景与共振响应相关性

Study on the correlations between the background and resonant response of super-tall buildings

国内外风工程界在超高层建筑结构的风振分析中习惯把风振响应分为背景和共振2部分,再通过平方和开方法计算结构总的响应,这种处理方法忽略了背景与共振分量的相关性,从而有可能导致风振响应的计算结果产生误差.文章以530 m高的广州东塔为例,进行高频底座天平测力风洞试验,采用近似算法与精确算法分别计算其风振响应,对背景响应和共振响应的相关性进行分析,并采用相关性系数来定量表达2者的相关性.结果表明,对于本案例,多数风向角下2者的相关系数大致在-10%～10%之间变化,但在结构响应峰值处其相关系数往往较大,最高可达-86%.忽略背景响应与共振响应的相关性在部分情况下会导致响应被低估,而在有时则会导致响应被高估.因此,建议直接采用精确算法计算超高层建筑的风振响应.

Traditionally, the wind-induced vibration of a tall building can be categorized into two parts, the background response and the resonant response, and the total response is then computed by the SRSS （Square Root of the Sum of the Squares） method. This treatment helps understand the mechanism of wind-induced vibration for a tall building at the expense of computational errors. In this study, a super-tall building, the Guangzhou East Tower with a height of 530 m is sampled to show the relative error between the results by the accurate method and those obtained from the approximate method. The wind tunnel test is carried out by adopting the high-frequency force balance technique, and some wind-induced responses such as base overturning moment response, displacement response and acceleration response atop the building. The correlations between the back-ground response and the resonant response are analyzed. The results indicate that for the Guangzhou East Tow- er, the correlation coefficients vary mainly in the range of - 10% to 10% under most wind directions, however in some particular wind direction at which the maximum response occurs, the correlation coefficients are usually large. The maximum correlation coefficient is around 86%. Neglecting the correlation between the background response and the resonant response could cause overestimation or underestimation of the structural response. It is suggested that the accurate method be adopted directly to compute the wind-induced response of super-tall buildings.