Impact responses of prestressing tendons in railway concrete sleepers in high speed rail environments
Prestressed concrete sleepers (or railroad ties) are designed in order to carry and transfer the wheel loads from the rails to the ground and are installed as the crosstie beam support in railway track systems. They are subjected to impact loading conditions that are resulted from train operations over wheel or rail abnormalities, such as flat wheels, dipped rails, crossing transfers, rail squats, corrugation, etc. The magnitude of the shock load relies on various factors such as axle load, types of wheel/rail imperfections, speeds of vehicle, track stiffness, etc. This paper demonstrates the development of finite element modelling to evaluate the dynamic responses of prestressed tendons or wires embedded in concrete sleepers, particularly under a variety of impact loads. The force prediction under high speed rail environment was conducted using D-TRACK. The 3D finite element model of prestressed concrete sleeper has been developed using a finite element package, LS-Dyna. It has been verified by the experiments carried out using the high capacity drop-weight impact machine at the University of Wollon-gong, Australia. The experimental results provide very good correlation with numerical simulations. In this paper, the numerical studies are extended to evaluate the dynamic behaviors of high strength steel wires and their responses under different parameters in high speed rail environments. The outcome of this study can potentially lead to the dynamic design guideline for prestressed concrete sleepers under low-cycle fatigues. Future work includes more detailed investigation into the effect of track bed and rail pad degradation subject to higher frequency impacts.
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