双幅并行连续刚构桥箱梁断面三分力系数气动干扰效应数值模拟

以咸阳至旬邑高速公路三水河连续刚构桥箱梁桥为依托，采用CFD软件FLUENT计算了主梁跨中及支点断面在不同风攻角、双幅桥间距及有无护栏情况下的风阻力系数，并与相同条件下的单幅桥进行对比，研究了双幅桥风阻力气动干扰效应。结果表明：气动干扰效应对双幅桥风荷载均有影响，总体上随双幅桥间距减小而增大，随结构尺寸增大而增大，而随风攻角的变化规律不明显；上游桥阻力系数干扰因子为0．994～1．147，略大于1或在1附近变化，表明气动干扰效应对上游桥的阻力系数影响较小；下游桥阻力系数干扰因子为-0．356—0．973，变化范围很大，表明气动干扰效应对下游桥的阻力系数影响很大，双幅桥间距较小时来流风对下游桥的作用甚至表现为吸力。

Numerical Study on Static Aerodynamic Coefficients Aerodynamic Interference Effects of the Box girder Section of Continuous Rigid Frame Bridge with Close Twin Deck

Taking San-Shui-He bridge, a continuous rigid frame bridge with close twin deck in Xianyang to Xunyi Highway, as an example, wind forces and resistance coefficients on the girder＇ s mid- span and surpport section are simulated by FLUENT, with guardrail or without, and in different wind an- gle of attack and different gap of the twin deck. The wind resistance aerodynamic interference effects of the bridge with twin deck are studied by comparing the results to that of the single deck bridge under same conditions. The results show that the aerodynamic interference effect has impact on wind loads on the double - width bridge both, and the degree of influence increase as the spacing of the two deck de- creases, as the size of the structure increases, while not change significantly with the wind angle of attack changes. Interference factor of the upstream bridge drag coefficient is O. 994 to 1. 147, slightly larger than 1 or in a nearby change, indicating that the aerodynamic interference effects have relatively small impact on the resistance coefficient of the upstream bridge. Interference factor of the downstream bridge drag coefficient is - 0. 356 to 0. 973, fluctuated widely, indicating the aerodynamic interference effects have great impact on the drag coefficient of the downstream bridge. When the gap of the two deck is small, the effect of comin~ wind to downstream bridges even performed for suction.