基于小波变换的苏通大桥非平稳抖振响应演变谱实测研究

FIELD MEASUREMENT STUDY ON THE EPSD OF NON-STATIONARY BUFFETING RESPONSE OF SUTONG BRIDGE BASED ON WT

台风风速具有较为明显的非平稳特征,使得非平稳风荷载作用下大跨斜拉桥的动力响应也势必表现出非平稳特性。为考察台风作用下大跨桥梁抖振响应的非平稳性,该文以苏通大桥为研究背景,采用基于小波变换的非平稳时间序列演变功率谱密度估计方法分析了该桥在"海葵"和"达维"台风期间的非平稳抖振响应。研究表明,苏通大桥主梁振动能量主要集中在若干特定频段内;由于台风风速存在非平稳性,主梁抖振响应也表现出一定程度的非平稳特征;基于小波变换的演变谱估计方法适用于开展实测结构响应的演变特性分析,可较好地弥补传统傅里叶方法用于非平稳分析的不足。研究结论可用于验证大跨度斜拉桥非平稳抖振分析理论的可靠性,同时可为大跨度斜拉桥的抗风设计提供参考。

The wind speed of typhoon exhibits obvious non-stationary characteristics, which leads to the non-stationary features in the dynamic response of long-span cable-stayed bridges. To investigate the non-stationary characteristics existing in buffeting response of long-span bridges under the action of typhoon, Sutong Bridge is taken as the research object. Based on wavelet transform（WT）, the evolutionary power spectral density（EPSD） estimation method is employed to analyze the non-stationary buffeting response of Sutong Bridge during Typhoon Haikui and Damrey. The analytical results show that the vibration energy of the girder in Sutong Bridge is predominated by specific frequencies. Due to the non-stationary features of the typhoons, the buffeting response of the main girder exhibits non-stationary characteristics to some extent as well. The wavelet-based EPSD estimation method is suitable for analyzing the evolutionary characteristics of the measured structural response, and it is a good supplement for the traditional Fourier method in non-stationary analysis. The results can be utilized to validate the reliability of the non-stationary buffeting analysis theory and provide references for the wind-resistant design of long-span cable-stayed bridges.