Effect of track flexibility on fatigue life of railway concrete slab track

Abstract

Although reduction of fastening system stiffness and interlayer stiffness are two main approaches to increase the track flexibility, it is not obvious which one has a greater effect on decreasing the fatigue life of the concrete slab in different conditions. This research was carried to eliminate this limitation. In this regard, a numerical model of vehicle/slab track interaction was developed in the FORTRAN environment and a code was written in MATLAB to calculate the fatigue life of concrete slab based on the compressive and tensile stresses, Miner’s rule and a proper concrete fatigue life model. Through a parametric study, the effects of different parameters such as concrete slab thickness, concrete compressive strength, vehicle speed and vehicle axle load on the influences of rail-pad and interlayer stiffness on the fatigue life of concrete slab were investigated. The results obtained from the parametric study were summarized in contour figures to find a proper strategy to simultaneous increase in the railway track flexibility and the fatigue life. It was shown that decreasing the rail-pad stiffness and increasing the interlayer stiffness leads to simultaneous increase in the flexibility and fatigue life of railway concrete slab track. It was found that the track flexibility and fatigue life reach an acceptable level when the rail-pad and interlayer stiffness is lower and greater than 60 and 2500 MN/m, respectively.