基于希尔伯特-黄变换的超高层建筑模态参数识别

Identification of Modal Parameters of Super High Buildings Based on Hilbert-Huang Transform

基于改进的希尔伯特—黄变换（HHT）即结合随机减量技术（RDT）的HHT对7~9级风力作用下,超高层建筑——上海金茂大厦的加速度响应现场实测数据进行分析与处理,以识别出上海金茂大厦东西和南北方向的第12、阶自振频率及相应的阻尼比。在识别中,为了避免结构模态的混叠现象,本文引入了巴特沃斯带通滤波器来对加速度实测数据实行滤波处理。识别结果显示：上海金茂大厦东西方向和南北方向的第1阶自振频率近似相等,但是东西方向和南北方向的第2阶自振频率相差较大;结构东西和南北方向的阻尼比皆小于结构材料的阻尼比,而且随着模态阶数的增大识别出的阻尼比标准差呈现增大的趋势。这些研究结果对未来超高层建筑的设计具有借鉴意义。同时,识别结果也表明,HHT＋RDT＋巴特沃斯带通滤波器方法可以有效地识别出超高层建筑的模态参数。

The improved Hilbert-Huang transform（HHT）,coupled with the random decrement technique（RDT）,is been proposed in this study to analyze the wind-induced responses of Shanghai Jin Mao Tower with height of 420.5m under wind-force of 7～9 grades,so the first and second natural frequencies and the corresponding damping ratios are obtained in its east-west and north-south direction.To avoid the mode mixing problems in the identification process,the Butterworth band-pass filter is then taken into account to filter the field measurement data of acceleration responses.Numerical results reveal that the first frequency in both directions is almost identical,but the second frequency in the north-south direction is greater than that in the west-east direction.Additionally,the damping ratio of Shanghai Jin Mao Tower is less than that of material itself.Likewise, with the modal order increasing,the standard deviations of the identified damping ratios increase.These findings will give a reference to the wind-resistant design and construction of super high buildings in the future.Simultaneously,numerical results also indicted that the improved HHT,coupled with both the RDT and Butterworth band-pass filter,is able to identify the modal parameters of super high buildings commendably and effectively.