Continuous welded rail (CWR) on a bridge structure typically experiences a large amount of additional longitudinal axial forces due to longitudinal rail-structure (or track-bridge) interaction under temperature change and train vertical and traction/braking load effect. In order to reduce the additional axial forces, a special type of fastener, such as zero longitudinal restraint (ZLR) and reduced longitudinal restraint (RLR) or rail expansion joint (REJ) should be applied. Sliding slab track system is developed to reduce the effect of rail-structure interaction through the application of a low-frictional sliding layer between slab track and bridge structure. This study presents a track-bridge interaction analysis of the sliding slab track and compares them with conventional fixed slab track on bridges. Various types of span length and longitudinal profiles of bridges are considered in the analysis, which also include multiple continuous spans and extra-dosed bridges. The analysis found that the sliding slab track can reduce the additional axial forces of the continuous welded rail from 80% to 90%, and the difference is more significant for long and continuous span bridge. By the application of the sliding slab track, the use of any other special type of rail fasteners or REJ can be avoided. In addition, span length will not be restricted by the rail-structure interaction effect in planning the railway bridge layout. Continuous span bridge has been usually avoided for railway bridges, but it is preferred for the application of the sliding slab track because the interaction effect can mostly be removed. A continuous span bridge usually has an economical cross-section for the bridge girder, pier and foundation and better dynamic characteristics compared to simple span bridge, and its application eventually will reduce the construction cost of the railway infrastructure.
Comparative Analysis of Track-Bridge Interaction of Sliding Slab Track and Rail Expansion Joint for Long-Span Railway Bridge
