Wind field characteristics on a bridge site under complex mountain terrain

In order to obtain wind field characteristics on a bridge site on a complex mountain terrain, small-scale topographic wind-tunnel model tests are employed. The variation characteristics of the mean wind speed, wind attack angle, turbulent intensity and turbulence integral scale with respect to the wind azimuth and measuring point position are analyzed. The changes of the wind speed spectrum of typical measuring points on the complex mountain terrain are also studied. The results show that the mean wind speeds of all the measuring points on the bridge site are less than that of the gradient height. When wind blows along the valley, significant positive attack angles are produced due to the wind climbing effect, with the maximum value reaching +35.3°. The along-wind and crosswind turbulent intensities in this wind direction reach their minimum values as low as nearly 10%, and become larger in other wind directions. The turbulence integral scale in this direction is much larger than that in other directions, and increases with the increasing height of the measuring point. The wind speed power spectrum in the direction has significant differences compared with the incoming wind speed spectrum, of which the energy in the high frequency section increases significantly and the feature of the single peak diminishes.