Numerical Investigation of Rail Bending Behaviour Focusing on the Effect of Track Modulus

Thorough understanding of steel rail response to wheel load is a key step towards design and evaluation of the railway track structure. In current practice, maximum vertical deflection and bending moment are calculated using the theory of infinite beam on continuous elastic foundation (Winkler model), in which the foundation stiffness is assumed as constant. However, variation of track modulus along the rail is an inherent feature of the railway track structure. Inevitable variation in local geology, layer properties, layer thickness and track construction procedure along the track disturb track support uniformity. Track modulus can also rapidly change over a short length of the track at transition zones or at the locations of local problems, such as hanging or broken ties. This study aims to investigate the effect of track modulus variation on rail bending response using finite element method. In the proposed dynamic track model, various track modulus distributions are considered and track response to a moving wheel load set is calculated using direct integration time history analysis. The envelope profile of the rail maximum vertical deflection and bending moment derived from finite element models are then compared with the corresponding Winkler model results.