Research on Wind Field Characteristics Measured by Lidar in a U-Shaped Valley at a Bridge Site

Abstract

Currently, research on wind fields of U-shaped valleys is rarely reported, and anemometers or wind observation towers are usually used for field measurement, but the measured position is limited and the cost is high. In order to study the wind characteristics in a mountainous U-shaped valley, a long-range, all-weather, high-precision Wind3D 6000 lidar was placed at a bridge site located in a U-shaped valley. Then, according to the data effective ratio and wind speed, nearly 6 months of original data ranging from 0 m to 810 m were analyzed statistically. It was found that the spatio-temporal distribution of wind speed and direction is obviously not uniform, and the wind parameters are correlated among different virtual wind towers (VWTs). By classification, the effective data of midspan position is taken as the research object, and the wind speed profile is divided into three categories. Type-1 shows disorderly characteristics; Type-2 shows a linear relationship; and Type-3 shows a nonlinear relationship. The wind direction is consistent with the main wind direction at the bridge site and the average wind direction of different VWTs has a high consistency. The concept of wind-direction deflection rate is put forward to describe the variation of wind direction with height. These measured wind parameters could be used as a reference for bridge wind-resistant design.

Keywords

• bridge engineering
• wind characteristics
• field measurement
• U-shaped valley
• lidar
• bridge site