邻近三幅桥气动干扰效应对桥梁抗风稳定性的影响

Influences of Aerodynamic Interference Effects of Adjacent Three Separated Deck Bridges on Wind Stability of Bridges

为研究邻近三幅桥的气动干扰效应,以宁波甬江上2座邻近的桥梁(甬江铁路桥——单幅混合梁斜拉桥和甬江公路桥——双幅结合梁斜拉桥)为背景,对平行的三幅桥梁节段模型(缩尺比1∶60)进行风洞试验,分析三幅桥面之间气动干扰效应对桥梁成桥和施工状态颤振稳定性和涡振特性的影响。结果表明:邻近桥梁的气动干扰效应使平行多幅桥的颤振临界风速明显降低,且对最下风侧桥梁的颤振临界风速影响最大;该气动干扰效应对主梁断面的A*2项气动阻尼(对系统扭转运动起稳定作用)影响不大,但会导致下风侧主梁断面的A_1*×H_3*项气动阻尼(驱动流线箱梁发生弯扭耦合颤振)增大;该气动干扰将对下风侧桥梁的涡振性能产生影响,特别是扭转涡振性能。

To investigate the aerodynamic interference effects of the adjacent three separated deck bridges ,two adjacent bridges over the Yongjiang River in Ningbo （the Yongjiang River Rail‐way Bridge ,a single‐deck hybrid girder cable‐stayed bridge and the Yongjiang River Highway Bridge ,a twin‐deck composite girder cable‐stayed bridge） were cited as the examples ,the wind tunnel tests for the sectional models （the scaled‐dow n ratio being 1∶60） of the parallel three sepa‐rated deck bridges were made and the influences of the aerodynamic interference effects among the three separated deck bridges on the flutter stability and vortex‐induced vibration performance of the bridges in the completion and construction state w ere analyzed .T he results of the analysis in‐dicate that the aerodynamic interference effects of the adjacent multiple deck bridges cause the flut‐ter critical wind speeds of the bridges to significantly decrease and the influences of the effects on the flutter critical wind speed of the bridge on the most leeward side are the greatest .The influ‐ences of the effects on the aerodynamic damping terms A2^＊ （to play the role of the stability for the system torsion motion） of the main girder sections are not great ,but will cause the aerodynamic damping terms A1^＊ × H3^＊ （to drive the streamlined box girders to generate the bending and torsion coupling flutter） of the main girder sections on the leeward side to increase .The aerodynamic in‐terference can generate influences on the vortex‐induced vibration performance of the bridges on the leeward side ,particularly the torsional vortex‐induced vibration performance .