带高防护结构的边箱叠合梁斜拉桥涡振性能及抑振措施研究

为研究跨铁路站场的带高防护结构边箱叠合梁斜拉桥的涡振性能及抑振措施,开展1:50节段模型涡激振动风洞试验研究。试验分析风攻角(+3°,0°和-3°)以及防护结构对主梁涡振性能的影响。在此基础上,综合测试水平稳定板、梁底稳定板、风嘴、改变防护结构透风率等气动措施对桥梁涡振性能的提升效果。试验结果表明:带高防护结构的边箱叠合梁涡振性能较差,3个风攻角工况均出现了大幅竖向涡激振动;防护结构以及断面本身较钝的外形造成了主梁的气动不稳定,考虑到其本身较明显的钝体效应,建议在断面两侧安装风嘴;采用风嘴+两道梁底稳定板的方式能显著提高主梁涡振性能;在安装风嘴的基础上,增大防护结构下部实心段的透风率能够较好的控制主梁涡激振动。

Experimental study on vortex-induced vibration performance and aerodynamic countermeasures for a double-box composite beam cable stayed bridge with high protective structure

To investigate the vortex-induced vibration(VIV) performance and aerodynamic countermeasures for a double-box composite beam cable-stayed bridge with high protective structure across a railway yard, a series of wind tunnel tests were conducted with a 1:50 section model. The effects of wind attack angles(+3°, 0°,-3°) and high protective structure on the aerodynamic performance of double-box composite beam were investigated. Furthermore, the influence of some wide used countermeasures such as horizontal stabilization plate, baffle plate, wind fairing and ventilation ratio of protective structure on VIV performance were also investigated respectively. The results indicate that the VIV performance of original double-box composite beam with high protectivestructure is poor, and large vertical vortex-induced vibration occurs at the three wind attack angles. The high protectivestructure and bluff body characteristic result in the VIV of double-box composite beam. Considering the significant bluff body effect, it is recommended to install wind fairing on both sides of the section. The countermeasures of wind fairing + two baffle plate can significantly improve the VIV performance. Increasing the ventilation ratio of the protective structure of double-box composite beam with wind fairing can suppress the VIV effectively.