轨道结构形式对箱梁中高频振动的影响研究

为探讨不同轨道结构对桥梁中高频振动的影响，在频域内建立考虑多轮对相互影响的车辆-轨道系统耦合模型和桥梁有限元模型，以某城市轨道交通30 m简支箱梁的现场动载试验为依据，对所建模型进行验证。在此基础上，采用数值方法就三种轨道结构形式（埋入式轨枕、梯形轨枕以及钢弹簧浮置板）对箱梁中高频振动的影响规律及原因进行了探讨。结果表明：“车轮-轨道系统”的固有频率影响轮轨力的峰值频段；频率低于“钢轨-扣件系统”的固有频率时，钢轨的动柔度受到轨道结构形式的影响；各轨道结构系统的固有频率决定着力传递率的衰减趋势，并在该固有频率附近放大力传递率；轮轨力（外因）与力传递率（内因）共同决定着传递到箱梁上的力，从而影响箱梁中高频振动；对于箱梁中高频振动的减振效果而言，钢弹簧浮置板最优，梯形轨枕次之，埋入式轨枕最差。

Study on the influences of different tracks on the medium- and high-frequency vibrations of a box girder

In order to study the influences of different tracks on the medium- and high-frequency vibrations of bridge, the vehicle-track coupling model in frequency domain and the FEM model of bridge are built considering the influences of multiple wheels. The coupling model is verified based on the dynamic test of one 30m simply-supported box girder in an urban rail transit. Furthermore, based on the numerical method, the influencing rules of three tracks structures (embedded sleeper, trapezoidal sleeper and steel spring floating slab) on the medium- and high-frequency vibrations of box girder and the corresponding causes are discussed. Results show that: the natural frequency of wheel-rail system influences the peak frequency band of wheel-rail force. When the vibration frequency is lower than the natural frequency of rail-fastening system, the type of track structure affects the dynamic compliance of rail. The nature frequency of track structure determines the attenuation trend of the force transmission ratio, and the force transmission ratio can be enlarged near the nature frequency of track structure. Wheel-rail force (external reason) and the force transmission ratio (internal reason) jointly determine the forces transmitted to the box girder, thus affecting the medium- and high-frequency vibrations of the box girder. As for the vibration reduction performances of three track structures, the best is the steel spring floating slab, the second is the trapezoidal sleeper and the worst is the embedded sleeper.