大跨度平行双幅桥面颤振性能干扰效应

以某大跨度平行双幅桥为背景,基于弹簧悬挂节段模型风洞试验和二维三自由度颤振分析理论,分析了叠合梁断面和箱梁断面两种常用桥梁断面形式的双幅桥的颤振性能及颤振驱动机理。研究表明,叠合梁断面双幅桥具有明显的攻角效应,0°攻角时双幅桥的颤振性能大幅降低,但大攻角下气动干扰效应对其颤振性能影响不大;而箱梁断面双幅桥的攻角效应并不明显,各攻角下其颤振临界风速比单幅桥均降低20%～25%。气动干扰效应不仅会降低颤振临界风速,还会使得桥面的颤振形态发生改变;两类断面的颤振驱动机理并不相同,气动干扰也致使上下游桥面的颤振驱动机理发生改变。

Interference Effect on Flutter Performance of Long Span Bridges with Parallel Twin Decks

The aerodynamic performance of long-span parallel twin-deck bridge is more complicated than that of single deck bridge as a result of the interference effects between two decks. By using sectional-model wind tunnel tests and two-dimensional three-degree-of-freedom (2D-3DOF) method, flutter performances and mechanisms for a long-span parallel twin-deck bridge with two commonly used sections, the composite girder and box girder, were investigated. The results show that the effects of wind attack angle on twin-deck bridges with composite girder sections are significant. Flutter performances of twin-deck bridge worsens considerably at 0 degree angle of attack, while the aerodynamic interference has little effect on those at large angle of attack. However, effects of wind attack angle on bridge with box girder section is not obvious. The flutter critical wind speeds of twin-deck bridges are 20% to 25% lower than those of single-deck bridges. Aerodynamic interference effects not only decrease flutter critical wind speeds, but also alter flutter modes. Flutter mechanisms corresponding to two section types are different, and those for upstream and downstream decks are also changed by aerodynamic interference.