FIELD MEASUREMENT OF WIND CHARACTERISTICS OF A BRIDGE SITE WITH COMPLEX YELLOW RIVER TERRAIN

Using a bridge across the Yellow River as an example, an 85 m tall wind observation tower was built to measure the wind speed and direction at 10 m, 30 m, 50 m and 80 m high. The measured wind data were transmitted by means of GPRS. A program based MATLAB environment was developed to calculate the wind speed and direction from the measured wind data. The results show that the average wind speeds along height direction generally obey a power-law distribution. The wind profile index fitted value from strong wind data is about 0.167, which is near to a class B roughness surface as recommended by the Wind-Resistant Design Specification for Highway Bridges. The average attack angle of strong wind at 10 meters high (defined as having a wind speed larger than 10 m/s with 10min intervals) is in the range of -4.9° to 6.7°, and the average attack angle of strong wind at 80 meters high is in the range of -4.4° to 5.3°. The turbulent intensity and wind spectrum of the turbulent wind at main deck level are close to the values recommended by the Wind-Resistant Design Specification for Highway Bridges.