摩擦型中央扣在超大规模单跨悬索桥的应用

Application of Friction Central Buckle in Mega Single-span Suspension Bridge

为研究摩擦型中央扣对超大跨单跨悬索桥静动力性能的影响规律,以某主跨2 180 m单跨钢桁梁悬索桥为研究对象,采用有限元分析方法,建立了三维空间有限元分析模型。对设置柔性中央扣、摩擦型中央扣、梁端约束装置及其组合应用等不同工况的大桥进行了静动力特性分析。重点关注梁端位移、跨中缆梁相对位移、桥塔内力、中央扣内力及应力幅值,明确了不同工况对超大跨悬索桥静动力性能的影响。开展了风-随机车流-桥梁耦合振动仿真分析,研究了运营阶段设置摩擦型中央扣对主梁在风和随机车流共同作用下的纵向变形规律。在此基础上,提出了大跨径悬索桥中央扣设置建议。结果表明:设置中央扣可大幅降低静力和地震作用时的梁端纵向位移及缆梁间相对位移,有效减小汽车荷载作用时梁端及缆梁间累计位移;当中央扣与梁端约束装置组合应用时,对超大跨悬索桥纵向位移控制效果更佳,但会增大梁端限位装置内力;摩擦型中央扣可有效解决普通柔性中央扣地震作用时内力大的问题,当与梁端约束装置组合应用时,摩擦型中央扣内力进一步减小。根据研究结果,可将摩擦型中央扣作为一种辅助附加措施与梁端约束装置进行组合应用,可增大桥梁纵向刚度,降低随机车流、风及制动力等频遇荷载下缆梁的相对位移。

In order to study the influence of friction central buckle on the static and dynamic performance of mega single-span suspension bridge,on the study background of a single-span steel truss girder suspension bridge with 2180 m main span,a 3D finite element analysis model is established by using the finite element analysis method.The static and dynamic characteristics of the bridge under different working conditions(flexible central buckle,friction central buckle,girder end restraint device and their combined applications)are analyzed.Focusing on the amplitudes of displacement of girder end,relative displacement between cable and girder at mid-span,internal force of pylon,central buckle force and stress,the influence of different working conditions on static and dynamic performance of mega long-span suspension bridge are clarified.The simulation analysis of wind-stochastic traffic-bridge coupling vibration is conducted,and the longitudinal deformation rule of the girder with friction central buckle under the combined action of wind and stochastic traffic during the operation phase is studied.On this basis,the suggestion for installing central buckle on long-span suspension bridge is proposed.The result shows that(1)installing central buckle can greatly reduce the longitudinal displacement of the girder end and the relative displacement between the cable and the girder under static and seismic actions,and reduce the cumulative displacement between the girder and the cable under vehicle load effectively;(2)when the central buckle is combined with the girder end restraint device,the longitudinal displacement control effect of the mega long-span suspension bridge is better,but the internal force of the girder end restraint device will increase;(3)the problem of large force of ordinary flexible central buckle under earthquake can be solved effectively by using the friction central buckle,and the internal force of the friction central buckle is reduced further when combined with girder end restraint devices.According to the study result,the friction central buckle can be used for an auxiliary additional measure in combination with girder end restraint device to increase the longitudinal stiffness of the bridge,and reduce the relative displacement between cable and girder under frequent loads,i.e.,stochastic traffic,wind,and braking force.