Dynamic Performance of Unbonded Pre-Stressed Steel Bar in CRTS I Ballastless Slab Track under Train Load

With increasing vehicle operation speed and increasing service life, the damages to varying degrees occur on the unbonded pre-stressed steel bar in CRTS I ballastless slab track structure, and the fractured or sprung unbonded pre-stressed steel bars have already been found on different railway lines with ballastless track structure. Thus it is necessary to analyze the dynamic performance of unbonded pre-stressed steel bar in CRTS I ballastless slab track under train load in terms of time domain and frequency domain, including its force and deformation features. In this paper, based on the modal analysis, the relationship between impacting frequency induced by train load and natural frequency of unbonded pre-stressed steel bar is found. With the application of ANSYS/LS-DYNA explicit dynamic analytical software, the vertically coupled vehicle-track system calculation model is established to evaluate the indexes indicating the dynamic performance of unbonded pre-stressed steel bar in service like additional stress at various vehicle operation speed. The results show that the dynamic response of the steel bar is the most severe at the vehicle speed of 160km/h, but it cannot result in fracture. The action of train load is not the direct cause leading to the fractured unbonded pre-stressed steel bar.