Non-stationary buffeting response of suspension bridge in mountains based on time-varying power spectrum

The mountainous terrain is complex and the temperature changes greatly, which leads to the complex time and spatial characteristics of the mountain wind field. The wind field shows obvious non-stationary characteristics. The standard power spectrum only contains frequency domain information, which cannot accurately reflect the time-frequency domain characteristics of mountain wind. It will be inaccurate to simulate mountain wind speed based on standard power spectrum, so it is difficult to get accurate buffeting response of mountain bridge. In this paper, the wind speed is measured in mountainous areas, and its non-stationary evolution power spectral density (EPSD) is obtained by Priestley method. Taking the measured EPSD as the target, the fitting is conducted according to the model of time-varying PSD, so as to obtain the fitted EPSD of the measured wind speed. The buffeting response of suspension bridge under mountain wind field is studied by simulating mountain wind field with fitted EPSD. It is shown that the fitted time-varying power spectrum can better reflect the time-frequency characteristics of measured wind speed. In addition, the fitted EPSD can simulate the measured wind speed more accurately. Furthermore, the buffeting responses of suspension bridge with stationary, traditional non-stationary (modulation function) and mountain non-stationary (modified EPSD) wind fields are analyzed. The response based on modified EPSD is the biggest, which is 17% and 5% bigger than the stationary wind field and the traditional non-stationary wind field.