桥面不平度对主梁气动力及涡振性能的影响

Impact of Deck Roughness on Aerodynamic and VortexInduced Vibration Characteristics of Main Girder

为研究不同桥面状况下大跨度悬索桥气动力稳定性及涡振范围和极值的变化规律,以寸滩长江大桥为背景进行分析。选取3种桥面不平度,通过MATLAB编程模拟得到各桥面不平度的变化范围,在此基础上根据节段模型缩尺比选取相应的砂纸模拟3种桥面不平度,在风洞开展主梁节段模型静力三分力系数和涡振试验。利用CFD软件从微观上分析主梁周围的流线轮廓、压强及速度随桥面不平度的变化特征。结果表明:随桥面不平度的增加,在正攻角范围内,阻力系数CD减小,升力系数CL增大;桥面不平度对力矩系数CM基本没有影响。随着桥面不平度的增加,主梁的竖向涡振振幅、扭转涡振角度及扭转涡振区间减小,扭转涡振响应变化幅度大于竖向涡振响应。

To investigate the changing laws of the aerodynamic stability and the vortex-induced vibration ranges and extreme values of the main girder of long span suspension bridge under the different deck conditions,the Cuntan Changjiang River Bridge was taken as an example and was analyzed.Three kinds of the deck roughness were selected and by way of the MATLAB programming and simulation,the changing ranges of the different deck roughness were obtained.On the basis of the programming and simulation,the corresponding sandpapers were chosen to simulate the three kinds of the deck roughness according to the scale-down ratios of the sectional model and in the wind tunnel,the static three-component force coefficient and vortex-induced vibration tests for the sectional model of the main girder were carried out.The software CFD was also used to microscopically analyze the characteristics of the streamline profile,pressure intensity and speed around the main girder changing with the deck roughness.The results of the analysis demonstrate that with the increase of the deck roughness and in the ranges of the positive wind attack angles,the drag coefficient CDdecreases,the lift coefficient CLincreases and the deck roughness essentially has no impact on the moment coefficient CM.With the increase of the deck roughness,the amplitudes of the vertical vortex-induced vibration and the angles and intervals of the torsional vortexinduced vibration of the main girder decrease and the changing amplitudes of the torsional vortexinduced vibration responses are greater than those of the vertical vortex-induced vibration responses.