The identification of added mass and aerodynamic damping using HHT method under wind action

摘要

For the long-span roof structures which have relatively low frequency and light mass, the vibration property under the action of fluctuating wind is significantly influenced by the added mass and aerodynamic damping. Since the influence can be reflected by the change of structural frequency and damping ratio, the problem can be classified as modal parameter identification. Based on Hilbert-Huang Transform, Empirical Mode Decomposition method is applied on the output signal after IIR band pass filter. Then the Random Decrement Technique is used synchronously on all the components of degree of freedom to obtain the free decay signal of required mode, so the frequency, damping ratio and mode shape can be identified. The results of numerical example show that this method can restrain noise effectively and extract the modal parameters accurately. Taking the Geiger type cable dome as example, the added mass and aerodynamic damping under the action of fluctuating wind was identified according to the principle of highly similar mode shape, and the change law of these two parameters was also obtained compared with still air environment.