考虑轨道约束的高速铁路简支梁碰撞效应研究

Study of Pounding Effect of High-Speed Railway Simply-Supported Beam Bridge Considering Track Constraint

为研究轨道结构对简支梁桥碰撞效应的影响规律,以沪昆线上某4-32m简支箱梁为例,采用大质量法分析地震动的行波效应,用Kelvin单元分析桥梁碰撞,用非线性杆单元模拟梁轨接触,建立了考虑滑动支座摩阻力、桥墩弯矩曲率非线性和桩土共同作用的梁轨系统动力有限元模型,分析了一致激励和行波效应下考虑轨道约束的高速铁路简支梁桥碰撞效应,并对梁缝宽度、线路纵向阻力等设计参数进行了敏感性分析。结果表明:轨道结构对桥梁纵向位移起到了约束作用,可减弱甚至消除梁体间的碰撞效应;适当增加梁缝宽度,可大幅度减小梁体碰撞次数和撞击力;线路纵向阻力减弱时(如采用小阻力扣件时),梁体间的碰撞效应增强。

To study the law of impact of the track structure on the pounding effect of me high-speed railway simply-supported beam bridge, a 4-32 m span simply supported box beam bridge on Shanghai-Kunming High-Speed Railway was cited as an example, the effect of the ground motion traveling waves was analyzed, using the large mass method, the pounding of the bridge beams was analyzed, using the Kelvin element and the contact between the beam and track was simulated, using the nonlinear link element. The dynamic finite element model for the beam and track system considering the frictional resistance of the slide bearings, the pier moment--cur- vature nonlinearity and the pile～soil interaction was established, the pounding effect of the sim- ply-supported beam bridge considering the beam and track constraint under the uniform earth- quake excitation and traveling wave effect was analyzed and the sensitivity analysis of the design parameters like the beam gap width and railway line longitudinal resistance was made as well. The results of the analysis show that the track structure plays the role in constraining the longitu- dinal displacement of the bridge and can weaken or even eliminate the pounding effect between the beams. The proper increase o{ the beam gap width can greatly reduce the pounding frequencies and pounding forces of the beams and when the longitudinal resistance of the railway line weakens （e. g. the little resistant fasteners are used）, the pounding effect between the beams should be enhanced.