不同风障形式下桥梁断面行车风环境及颤振性能

摘要

为研究不同形式风障下的桥面风环境和结构颤振性能,以主跨为918 m的单箱悬索桥为对象,首先结合CFD数值模拟,比较3种风障下风速剖面及侧风折减系数的变化规律,进一步选取带椭圆形风障的主梁断面和无风障的原始断面开展节段模型颤振和测力风洞试验,分别对比研究风障对颤振临界风速和静力三分力系数的影响,最后借助二维三自由度方法分析设置风障前后的颤振发散驱动的变化.结果表明:设置风障能有效地降低行车高度内的平均风速,改善桥面风环境;在对比方案中,矩形断面的侧风折减效果最佳,而椭圆形风障对于侧风的折减效果可接受,且阻力系数小于其他形式;设置椭圆形风障后断面的阻力系数较原始断面提高明显,颤振临界风速小幅度的提高,断面颤振发散机理发生显著变化.%To investigate the crosswind environment and flutter performances of bridge deck with different wind barriers,a single-box-girder suspension bridge with the main span of 918 m was modeled by using the CFD.The wind speed profiles and crosswind reduction factors with types of wind barriers were compared.Then,the critical flutter wind speeds and three-component force coefficients with and without the superior wind barrier (ellipticshaped) were tested in sectional model wind tunnel tests.The diverging mechanism for two kinds of sections was studied based on 2d-3DOF method.Results show that wind barriers could effectively change crosswind environment at the range of driving height by decreasing the mean speed.The rectangular wind barrier is the best choice to reduce crosswind speed,while the elliptic wind barrier performs acceptable effects and presents a smaller drag coefficient.According to the wind tunnel test,the elliptic-shaped wind barrier could make the drag coefficient much larger than the initial section,and the critical flutter wind speed increases mildly.The analysis results by 2d-3DOF method indicate that the diverging mechanism changes quite noticeably.