干热河谷区大跨度钢桁梁悬索桥颤振性能研究

Study on flutter performance of a long-span suspension bridge with steel truss girder in dry-hot valley

针对某跨越干热河谷区深大峡谷的千米级钢桁梁悬索桥,通过节段模型风洞试验对其颤振性能进行了研究,确保了结构的颤振稳定性。首先,采用ANSYS软件对桥梁结构的动力特性进行了计算分析。然后,设计了相应的试验模型,并分析了竖弯阻尼比和扭转阻尼比对桥梁颤振性能的影响。最后,提出了一种气动优化措施使桥梁的颤振稳定性满足要求。研究结果表明:该钢桁梁悬索桥的颤振形态以扭转振动为主,因此,扭转阻尼比的改变对其颤振性能的影响将明显大于竖弯阻尼比;大风攻角来流下桥梁的颤振临界风速将会降低,如果封闭桥面系的中央开槽并在其下侧设置竖向中央稳定板,可以使该悬索桥的颤振临界风速满足颤振检验风速的要求。

Flutter performance of a kilometer-scale suspension bridge with steel truss girder in dry-hot valley with deep canyon was studied by section model wind tunnel test to ensure the structural flutter stability. Firstly,the dynamic characteristics of the bridge were calculated by the ANSYS software, and the corresponding test model was designed. Then the effects of vertical and torsional damping ratios on the structural flutter performance were analyzed. Finally, an aerodynamic optimization method was presented to ensure the flutter stability of the bridge. The results show that the effect of torsional damping ratio on the structural flutter performance is larger than that of vertical damping ratio due to the torsional divergent type instability. Large angles of attack make the critical flutter wind speed of the bridge decrease. If the central slot of bridge deck is closed and a vertical central stabilizer is installed below the deck,the critical flutter wind speed of the bridge will be larger than the checking wind speed.