台风作用下某高层建筑结构气动阻尼比的实测分析

Field measurements of the aerodynamic damping ratio of a high-rise building under action of typhoon

在台风"灿鸿"、"杜鹃"影响期间,对温州某矩形截面高层建筑进行了现场实测,得到其顶层的风速、风向及多个楼层的加速度响应数据。将加速度数据经EMD处理,应用ERA、ERA-NEx T及AR三种方法,对建筑结构的模态参数与气动阻尼动力特性进行了计算分析,结果表明:ERA、ERANEx T和AR这3种方法得出的频率值及振型都非常接近,频率差值不超过2%,即均可以用计算频率及分析判断振型;但振型阻尼比结果却不同,除一阶振型的比较接近外,其它各阶的数值都有一定程度偏差;在一定频率段的振型结构阻尼比拟合曲线中,柯西(Caughey)阻尼模型(b=2时)与Sergio Lagomarsino经验曲线最为接近;一阶振型气动阻尼比均为负值,且随着风速的增大,其值有减小的趋势,其中ERA、AR方法的斜率较为相似,而ERA-NEx T方法的下降速率较为平缓。

During the passage of typhoons ＂Chan-hom＂ and＂ Dujuan＂ , the on-site measurements of a rectangular highrise buildings in Wenzhou City was carried out, which include wind speed, wind direction of the top floor and the response data of multiple floor acceleration. The acceleration response data were processed by EMD and ERA, ERA-NExT and AR methods, the modal parameters and aerodynamic damping characteristics of building structure were calculated and analyzed. The results show that the frequencies and models obtained from three methods, i. e. ERA,ERA-NexT and AR are very close, the frequency difference is not more than 2% ,which all can be used to calculate the frequency and analyze the vibration mode. But their damping ratio has different results in certain degree except for the first-order mode. At a certain frequency, Caughey damping model（ b = 2）curve is closest to Sergio Lagomarsino experience curve. The first-order modal aerodynamic damping ratio are all negative, and their values decrease with increase of wind speed, and the drop slopes of the ratio obtained from ERA is similar to that from AR, but the slope from ERA-NExT is more gentle.