Model test study of wind field characteristics of long-span bridge site in mountainous valley terrain

Taking Aizhai bridge—a super long suspension bridge with a main span of 1176m as backgrond,this paper bring forward a way to test the wind field characteristic of deep valley in wind tunnel.The effects of valley wind on design wind speed of bridge were mainly studied and presented.According to the ratio of wind speed at the height of bridge deck in the terrain model to the gradient wind speed of the wind field in front of valley model,a method of calculating design wind speed of bridge by the ratio and actual gradient wind speed in front of the valley was proposed.Test results in wind tunnel show that the mean wind speed profile in valley changes along the bridge span,and it cannot be simulated as a uniform wind speed profile.The attack angle at the bridge deck altitude is higher than the scope of ±3° prescribed by the code and when considering the magnification effect of wind speed in valley,the height of measuring point and the shape of mountain on both sides should be taken into account.