Field Measurements Study on High-Altitude Wind Characteristics of Bridge Site in Deep Gorge

Long-span bridges built in deep gorges are usually inaccessible and it is difficult to obtain wind characteristics of these bridge sites from the wind-resistant design code owing to the complex terrain and the great gap between the deck and the valley bottom. To confirm the high-altitude wind characteristics of a bridge site in a deep gorge, field measurements of such properties were conducted using 3D sonic anemometers located in the mid-span and arranged on the catwalk during the construction process. A total of 7 899 valid fluctuating wind speed time series were obtained. On the basis of this data, the high-altitude wind characteristics of the bridge site were studied, including the average wind speed velocity, wind direction, wind attack angle, turbulence intensity, turbulence integral, and power spectrum densities. The results show that the impact of the landscape on the high-altitude wind characteristics of the bridge site in the deep gorge weakened substantially, while the wind attack angle tends to 0. Simultaneously, the turbulence integral at high altitude is more characteristic of that in plain regions, where the mean value is greater than that recommended by the wind-resistant design code.