基于结构健康监测的苏通大桥实测强风演变功率谱

Evolutionary Power Spectral Density of Recorded Strong Wind at Sutong Bridge Based on Structural Health Monitoring

对基于小波变换的非平稳时间序列演变功率谱密度函数的估计方法进行了总结.以苏通大桥结构健康监测系统实测的台风达维、海葵以及冬季强北风数据为研究对象,基于Morlet小波计算了上述3个实测典型强风的演变功率谱密度函数.实测风演变谱在时域内的均值与傅里叶谱吻合良好,验证了演变谱估计结果的准确性.实测强风的演变功率谱分析结果表明,脉动风的能量主要集中在低频部分,且脉动风速功率谱随时间变化显著,具有较强的非平稳特性.基于平稳随机过程假设的传统风谱计算方法无法准确描述实测强风风谱的非平稳特征.研究结论可为桥址区三维非平稳脉动风场的准确模拟以及强/台风作用下苏通大桥的非平稳抖振分析提供实测参考.

The methods for estimating the evolutionary power spectral density （EPSD） of nonstationary time series using the wavelet transform were summarized. Taking typhoon Dawei, typhoon Haikui and the winter monsoon recorded by the structural health monitoring system （SHMS） of Sutong Bridge were as examples, the EPSDs of the three measured strong winds were calculated with the Morlet wavelet. The mean values of EPSDs in the time domain agree well with the traditional Fourier-based PSDs, which verifies the accuracy of the estimated results of the EPSDs. The analysis results of the EPSDs show that the energy of turbulence wind mainly concentrates on the low frequency range. Besides, the EPSDs of turbulence wind vary remarkably with time and possess strong nonstationary characteristics. Therefore, the traditional wind spectrum calculation method based on the hypothesis of the stationary random process cannot exactly describe the nonstationary characteristics of the measured strong wind spectrum. The conclusions can provide field measurement references for accurate simulation of 3D nonstationary turbulence wind field of bridges and nonstationary buffeting response analysis of Sutong Bridge under strong winds.