基于Hilbert-Huang变换的大跨屋盖气动阻尼识别

Aerodynamic damping identification of long-span roof based on Hilbert-Huang transform

当风流经大跨柔性屋盖时,屋盖在内外压共同作用下表现出显著的流固耦合特性.根据Hilbert-Huang变换的特点,在比较多种气动阻尼识别方法的基础上,提出联合采用经验模态分解法(EMD)、改进的随机减量法(MRDT)和Hilbert变换法(HT)进行大跨屋盖气动阻尼识别研究,并详细阐述了联合法的技术原理.通过大跨屋盖气弹模型风洞试验,将采集的信号经EMD法得到各阶模态响应(IMF),提取主要IMF经过MRDT、HT及带通滤波技术,识别出屋盖在四周封闭和突然开孔两种状态下的气动阻尼和固有频率.研究了在不同风速下屋盖气动阻尼的变化特性.在突然开孔时,气动阻尼对屋盖风致振动的影响不可忽略.

During wind flows around long-span flexible roofs, the fluid-structure interaction characteristic of the roof is significant. Hilbert-Huang Transform（HHT） is a newly developed powerful method for time series analysis. After reviewing many aerodynamic damping identification methods, a new identification method combined with empirical mode decomposition （EMD）, modified random decrement technique （MRDT） ,and Hilbert Transform（HT） for long-span roof was proposed. The aeroelastic model wind tunnel test was carried out to decompose the measured response data into modal responses using the EMD approach. Then, the MRDT, HT and band-pass filter approach were applied to main modal response to identify the natural frequency and damping ratio from the instantaneous amplitude and phase angle in the cases of building closure and sudden opening, respectively. It was found that the effect of aerodynamic damping in the case of sudden opening cannot be ignored.