A Study on Spatial Correlation and Power Spectrum of Natural Wind at Xihoumen Bridge

In design of a long-span bridge, gust response of the bridge is very important and must be taken into account. The long-span structure has low natural frequency, small mass and extremely low inherent damping. The spatial correlation and spectrum of the wind in the low-frequency range affect the gust response However, there are very limited field data about spatial correlation of natural wind and wind spectrum. In the wind-resistance design, the decay factor is set to be 7, which affects the wind-resistance design of a long span bridge. Therefore, natural wind were measured at Xihoumen Bridge and the wind speed spectrum and spatial correlation are calculated. The results show that the spatial correlation of the natural wind is lower than that specified in the wind-resistance design specification of China in the low-frequency ranges. The most appropriate wind spectrum and decay factors fitting to the field measurements are recommended. This means that there is a possibility of being able to modify the design specification of long span bridge concerning gust response. The calculated results provide credible technical guide to construction of Xihoumen Bridge and ensure wind resistance safety.