Abstract: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.
