大跨度连续刚构桥钝化主梁气动特性数值分析

Numerical simulation of aerodynamic characteristics of the blunt deck of long span continuous rigid frame bridges

以某大跨度连续刚构桥为工程背景,基于CFD商用软件FLUENT,对该桥主梁5个典型截面进行了定常与非定常计算,得到了不同工况下截面的三分力系数以及升力系数功率谱曲线。进一步讨论了钝化主梁截面静力及动力风荷载随梁高及攻角变化的规律,分析了FLUENT软件定常和非定常分析产生差异的原因,对比了成桥及施工状态主梁截面气动特性的差异,发展了一种基于非定常所得气动力时程判断结构涡振性能的方法。研究结论对实际工程具有一定的指导意义。

A long span continuous rigid frame bridge is regarded as the engineering example in this paper. Based on commercial software FLUENT for CFD analysis, a series of steady and unsteady analysis for five typical sections of this bridge arc carried to obtain aerodynamic coefficient and the lift coefficient power spectrum curve of deck section in different cases. Further the static and dynamic loads on the blunt deck sections with the different height at the various angle of attack are discussed. The reason why FLUENT offers the different results by steady and unsteady analysis is explored. The aerodynamic characteristics of deck sections at the service and the construction stage are compared. Based on the aerodynamic force history, a method is developed to evaluate the possible vortex-induced vibration. The obtained conclusion has some significance for the actual engineering.