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根据在北冕台风及汶川远震作用下某270 m高大楼顶层实测得到的加速度响应数据,对该高楼的结构动力参数和气动阻尼进行了识别。采用两种方法识别得到了该大楼的模态振动频率和阻尼比参数。一是经验模态分解(EMD)结合随机减量法(RDT)及希尔伯特黄变换法(简称EMD+RDT),另外采用了基于贝叶斯理论和快速傅里叶变换的识别方法。利用EMD+RDT法,还得到了阻尼比随加速度幅值的变化规律。两种方法识别得到了非常一致的模态振动频率结果。然而,在台风作用和地震作用下所识别的大楼阻尼比特性却表现出明显不同的特性和规律,这种不同主要是由于在台风作用下的建筑物阻尼包含了气动阻尼成分。如果把地震作用下识别得到的该高楼阻尼比作为结构阻尼比,台风条件下识别得出的阻尼比为总阻尼比,则二者相减可以作为该楼气动阻尼比的估计。
According to the measured acceleration response data of the top floor of a 270 m tall building under the influence of the North Coronation and the Wenchuan earthquake, the structural dynamic parameters and aerodynamic damping of the high building are identified. The modal vibration frequency and damping ratio parameters of the building were identified by two methods. One is empirical mode decomposition (EMD) combined with RDT and Hilbert-Huang transform (EMD + RDT), and another based on Bayesian theory and fast Fourier transform. By using EMD + RDT method, the variation of damping ratio with acceleration amplitude is also obtained. Both methods recognize very consistent modal vibrational frequency results. However, the damping characteristics of buildings identified under typhoon and earthquakes show distinct characteristics and regularities, mainly due to aerodynamic damping components contained in building damping under typhoon. If the damping ratio of the tall building identified by earthquake is taken as the structural damping ratio and the damping ratio identified under typhoon condition as the total damping ratio, the subtraction between the two can be used as an estimation of the aerodynamic damping ratio of the building.