Study on the Mechanical Performance of CRTS III and CRTS II Ballastless Track-Girder Systems Under Static Load

The proprietary China Railway Track System (CRTS) III ballastless track-girder system is gradually replacing the CRTS II system in high-speed railway projects across China. However, the influence of these two distinct track-structure systems on the overall stiffness of the track-girder system is often overlooked, and their boundary conditions with the box girder in finite element analysis (FEA) are sometimes not adequately addressed. To optimize the ballastless track structure for high-speed railways and improve finite element models (FEMs) of track-girder systems, it is essential to explore the differences in boundary conditions between the CRTS III-girder and CRTS II-girder systems. This study involved casting a 1:4 scale model of a three-span ballastless track-girder structure based on the CRTS III system prototype. Static load tests were conducted before and after laying the track structure to compare the structural performance of single-girder and track-girder systems under load. Refined FEMs of both the CRTS III and CRTS II systems were developed, allowing for a detailed analysis of their mechanical performance and damage evolution before and after track laying. The results indicated that, after track laying, the CRTS III system exhibited smaller reductions in vertical deflection and increases in vertical stiffness than the CRTS II system. The established FEM effectively simulated the cooperative working performance of the track-girder system above the neutral axis of the box girder. Compared with the CRTS II system, the CRTS III system limited the deformation of the top slab of the box girder, thereby reducing the likelihood of tensile failure at the end of the box girder top slab.