积雪条件下箱型桥梁断面气动力特性数值分析和风洞试验

Numerical Analysis and Wind Tunnel Test on Aerodynamic Characteristics of Box-shaped Bridge Section under Snow

以某斜拉桥为例,基于欧拉-欧拉理论,采用单向耦合的方法数值模拟风速为10,15,20 m/s条件下的桥面积雪的不均匀分布。同时,通过风洞试验研究3种不同风速下积雪的不均匀分布对主梁三分力系数、涡激振动性能以及颤振导数的影响。结果表明,积雪的沉积、侵蚀与壁面摩擦速度有紧密的联系,桥面背风侧积雪侵蚀量明显比迎风侧侵蚀量小,在尾流处侵蚀量最小。积雪对主梁的三分力系数影响较大,升力系数与扭矩系数绝对值增大40%左右,阻力系数绝对值增大15%左右。由于积雪作用,主梁+3°竖向涡激振动消失,同时,颤振导数A*4曲线斜率由负变为正,且不同风速下的积雪形状影响较小;当无量纲折减风速增大到一定程度时,H*2曲线相对平缓,而H*4基本保持不变。

Taking a cable-stayed bridge as an example and based on Euler-Euler theory, the uneven distribution of snow with different wind speeds of 10,15 and 20 m/s are simulated through one-way coupled method. Meanwhile,the impacts of uneven distribution of snow on three-component force coefficients,vortexinduced vibration characteristics,and flutter derivatives of girder are studied with wind tunnel test. The result shows that（ 1） the wall friction velocity is closely related with the deposition or erosion of snow,the snow on the leeward is eroded less than that on the windward and it reaches minimum in the wake of the bridge;（ 2）the influence of snow on the three-component force coefficients is significant： around 40% increase of absolute value of the lift coefficient and torque coefficient,and around 15% increase of drag coefficient;（ 3）due to the uneven distribution of snow,the vertical vortex-induced vibration of girder disappeared at wind attack angle of ＋ 3°,at the same time,the curve slope of A＊4is changed from negative to positive,and the uneven distribution of snow at different wind speeds have less different effect,when the non-dimensional reduction wind speed increased to a certain extent,the curve of H＊2is relatively flat,while the curve of H＊4remains unchanged.