2300m超大跨度扁平钢箱梁悬索桥颤振稳定性优化研究

Flutter stability optimization of a 2300m super long-span flat steel box girder suspension bridge

张皋过江通道南航道桥作为张皋过江通道的控制性工程,主桥采用主跨为2300 m的悬索桥设计,主梁采用扁平钢箱梁设计(宽度达51.7 m),跨中桥面距离海平面高度达77 m,具有桥梁跨度大、主梁宽度大、桥面高等特点。以上特性均导致了该桥对风的作用极为敏感,颤振设计面临着前所未有的挑战。研究表明该桥原设计断面无法达到颤振设计要求,就如何提高该类2000 m级整体钢箱梁悬索桥的颤振稳定性,采用1∶50节段模型风洞试验进行了研究。试验结果表明,上中央稳定板、下中央稳定板、水平稳定板以及改变人行道板倾角等传统气动措施已无法满足该类超大跨度桥梁的颤振设计需求,但在设置上、下中央稳定板的基础上,在人行道板端部设置斜45°导流板可显著提高该桥在各风攻角下的颤振临界风速至满足颤振设计要求,并通过1∶196全桥气弹模型风洞试验对该组合气动措施的有效性进行了验证。研究成果对采用整体箱梁的2000 m级超大跨度悬索桥颤振设计具有重要的参考意义。

As a control engineering project of Zhanggao river crossing channel,the Zhanggao south channel bridge adopts a suspension bridge design with the 2300 m main span,and 51.7 m width flat steel box main girder.The height of the mid-span bridge deck from sea level is 77 m.The characteristics of large span,large width main girder and high deck cause the bridge to be extremely sensitive to the effects of wind,and its flutter design faces unprecedented challenges.The research show that the original design girder cannot meet the flutter design requirements.1∶50 section model wind tunnel tests were used to study how to improve the flutter stability of the 2000 m class integral steel box girder suspension bridge.The test results show that traditional aerodynamic measures such as the upper central stabilizer,lower central stabilizer,horizontal stabilizer and the change of sidewalk slab angle can no longer meet the flutter design requirements of this type of super long-span bridge.However,on the basis of setting the upper and lower central stabilizer,the flutter critical wind speed of the bridge at different wind attack angle can be significantly increased by setting 45°inclined guide vanes at the end of the sidewalk slab to meet the flutter design requirements.The effectiveness of the combined aerodynamic measures was verified by using the 1∶196 full bridge aeroelastic model wind tunnel tests.The results have important reference significance for the flutter design of 2000 m class super long-span suspension bridges with integral box girders.