Numerical Simulation on Wind Characteristics at Y-shaped Valley Bridge Site
The wind field characteristics in complex mountainous areas are different from those in plain areas.The wind field is very complex and lacks a unified pattern,which has a significant impact on the structural vibration of large-span bridges.In order to study the influence of complex mountainous terrain on the wind field characteristics at bridge site,taking a cable-stayed bridge located at the intersection of several valleys as the engineering background.Based on ALOS digital elevation terrain model,the wind field characteristics at bridge site with different wind directions are calculated by CFD numerical simulation method.The influence of the main valleys at bridge site,and the local terrain at bridge site on the average wind speed,wind attack angle,wind deflection angle,and the vertical wind profile in the middle of bridge span along main beam is analyzed.The relationship between the average wind speed and the wind attack angle in the transverse direction of bridge is studied,and the relationship between the incoming flow conditions with wind speed amplification effect and the topographic characteristics of the bridge site is discussed qualitatively.The result shows that the wind characteristics at the Y-shaped valley bridge site are different from those at the general mountain bridge sites.When the incoming flow is along several relatively straight valleys,the average wind speed at bridge site is larger,and the wind speed at other wind directions is smaller.The bend of the valley results in the backflow and diversion of the incoming flow along the valley.In this case,the wind attack angle at the bridge site is large,the variation range of wind deflection angle along the main beam is relatively large,the horizontal wind speed is small,and there is no wind speed canyon amplification effect.The local topography of the valley at the intersection of bridge site has a great influence on the vertical wind profile in the middle of bridge span.The study result provides a basis for the determination of the design wind speed of bridge,and can provide guidance for the qualitative judgment of the wind characteristics at bridge site of Y-shaped valley.
bridge engineeringwind field characteristicsnumerical simulationY-shaped valleybridge site
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