基于精细建模的大跨度公轨两用桥梁端转角限制机理研究

Beam-end rotation angles of long span rail-cum-road bridges under road vehicles and trains are so significant that they could affect the serviceability of the track structures and even endanger running safety of the trains. Reasonable vehicle-track-bridge interaction analysis is required to find good solutions for these problems. However, former investigations usually ignored dynamic effect caused by moving road vehicles, neglected nonlinear dynamic interaction between girder and rail, and disregarded reasonable match of beam-end rotation angles and track structrues, leading to either potential safety hazard or construction waste.. The proposed project aims to improve calculation models and methods for local vibration and nonlinear interaction analysis of track and bridge structrues, so as to realize refined study on vehicle-track-bridge coupling vibration of long span rail-cum-road bridges. On this basis, the influence of beam-end rotation angles on train running performance and passenger feeling will be analyzed, the dynamic effect of fastening system at beam ends under moving vehicles will be investigated, the dominant factors influencing the beam-end rotation angles restriction under the condition of complex constitution will be illustrated, and the optimized control system will be proposed to achieve optimization design of track and bridge structrues. The research outcomes of this project can be utilized for optimal design, normal service and safe operation of the long span rail-cum-road bridges and the track structures on them.

汽车和列车荷载共同作用下大跨度公轨两用桥的梁端转角变位显著，是导致轨道结构失效并危及行车安全的控制因素，需依靠科学的车-轨-桥相互作用分析来寻求合理控制策略。目前研究极少将汽车视为动力子系统，不计轨桥非线性动力相互作用，忽视梁端转角与轨道结构的合理匹配，导致安全隐患或建设浪费。. 课题拟改进桥梁/轨道结构局部振动和非线性动力相互作用计算模型和计算方法，以实现对大跨度公轨两用桥车-轨-桥耦合振动的精细化分析。在此基础上，分析梁端转角对汽车乘坐舒适性、列车走行性的影响机理，探讨列车通过时梁端扣件系统动力特征，研究复杂构造条件下梁端转角限制的敏感参数，提出相应控制策略。为大跨度公轨两用桥及桥上轨道结构匹配设计、正常使用及安全运营提供理论支撑。

汽车和列车荷载共同作用下大跨度公轨两用桥的梁端转角变位显著，是导致扣件失效并危及行车安全的重要因素，如何合理限制大跨度公轨两用桥的梁端转角是工程中亟需解决的问题。对此，本项目编制了可考虑桥轨结构精细建模的车-轨-桥耦合系统振动计算程序。应用该计算程序，针对典型大跨度公轨两用桥进行了汽车-列车-轨道-桥梁耦合振动分析，研究了汽车动力效应对大跨度公轨两用桥动力响应及桥上列车走行性的影响，发现列车过桥时车体加速度最大值发生在梁端位置，由汽车、列车静载作用引起的梁端转角大小对列车车体加速度大小起控制作用，而梁端转角引起的车体振动具有瞬时冲击特点。指出梁端发生较大转角可满足列车走行性要求，但超过桥上无砟轨道扣件系统安全受力范围，扣件上拔力成为限制大跨度桥梁梁端转角的控制因素。提出了梁端采用过渡板及点支承浮置式轨道结构两类过渡装置来适应大跨度公轨两用桥梁端的大转角与大梁缝构造，研究了两类过渡装置的不同布置方式及结构参数对扣件受力的适应性，给出了两种措施情况可适应的最大梁端转角值，以及相应设置方法。参考本项目研究结论合理设置梁端过渡装置，可适当放宽梁端转角限制、节省造价。