Causes of Daily Strong Wind on Bridge Site in Deep Gorge with High Altitude and High Temperature Difference

In order to investigate the causes of daily strong wind on a bridge site in a deep gorge with a high altitude and a high temperature difference, the field measurement of wind characteristics was carried out on the Dadu River bridge site with the CAW600-RT automatic-weather-station (AWS), hand anemometer and portable thermometer. The property of wind environment on the bridge site was explored through analyzing its influence factors, including mean wind speed, temperature, sunlight, topography and so on. The research results show that the Dadu River bridge is located in a deep gorge with a high altitude and a high temperature difference, where strong wind occurs nearly every afternoon and its mean wind speed is often more than 10 m/s. The causes of strong wind can be classified into two types. The first type of wind is induced by large-scale general atmospheric circulation, while the second type of wind, i.e. daily strong wind, is driven by local thermal disequilibrium, and the daily strong wind is also influenced by local terrain and time-varying sunshine. Though frequent daily strong wind has not effect on the design wind speed of the bridge, it can affect bridge durability and driving comfort to some extent.