上中央与侧边稳定板对扁平箱梁气动性能的影响

Influence of Upper Center and Side Stabilizers on Aerodynamic Performance of Flat Box Girder

提升扁平箱梁的气动性能可同步提升大跨度桥梁的抗风性能,而增设气动措施则是简单易行的有效方法。基于节段模型风洞试验,在-5°~+5°风攻角范围内测试了某扁平箱梁的颤振和涡振性能,系统研究了上中央稳定板与侧边稳定板对改善扁平箱梁断面气动性能的影响。在此基础上,采用CFD数值模拟技术,研究了最不利风攻角下组合稳定板对流场的改善作用和涡致振动机理。风洞试验结果表明:扁平箱梁原设计断面在+3°与+5°风攻角下的颤振临界风速显著低于检验风速,且在各风攻角下均存在显著的涡激振动现象,气动性能不满足规范要求;设置上中央稳定板与侧边稳定板后,能显著提升扁平箱梁在+3°和+5°攻角下的颤振临界风速,可将最不利风攻角(+5°)下的颤振临界风速提高112%左右,并削弱检修车轨道对气动性能的影响;该组合措施能够显著抑制甚至完全消除扁平箱梁原有的涡激振动,相当于同时改善了颤振和涡振性能,使其满足设计要求。数值模拟计算结果表明:设置上中央稳定板与侧边稳定板后,断面会产生新的小尺度旋涡,可以干扰和削弱原设计断面在尾流处由于卡门涡所产生的周期性气动力,从而对涡振起到了有效的制振作用。

Improving the aerodynamic performance of flat box girder can simultaneously improve the wind resistant performance of long-span bridges,and adding aerodynamic measures is a simple and effective method.Based on the segmented model wind tunnel test,the flutter and vortex performances of a flat box girder are tested within the wind attack angle range of-5°-+5°,and the influences of upper center and side stabilizers on improving the aerodynamic performance of the cross-section of the flat box girder are systematically studied.On this basis,the improvement effects of combined stabilizers on the flow field and VIV mechanism at the most unfavorable wind attack angle are studied by using CFD numerical simulation technology.The wind tunnel test result shows that(1)the flutter critical wind speed at the original design section of the flat box girder is significantly smaller than the inspection wind speed at+3°and+5°wind attack angles,there is significant VIV phenomenon at all wind attack angles,and the aerodynamic performance does not meet the requirements of the specification;(2)after installing the upper central and side stabilizers,the flutter critical wind speed of the flat box girder can be significantly increased at+3°and+5°attack angles,and the flutter critical wind speed at the most unfavorable wind attack angle(+5°)can be increased by about 112%,and the influence of the maintenance vehicle track on the aerodynamic performance can be weakened;(3)the combined measure can significantly suppress and even eliminate the original VIV of the girder,equivalent to improving both flutter and vortex performances to meet the design requirements.The numerical simulation calculation result shows that after installing the upper central and side stabilizers,new small-scale vortices will be generated in the cross-section,which can interfere with and weaken the periodic aerodynamic force generated by the Karman vortices at the wake of the original designed cross-section,thereby effectively suppressing vortex vibration.