Improving the mechanical performance of timber railway sleepers with carbon fabric reinforcement: an experimental and numerical study

This paper proposes an externally bonded carbon fabric system to mitigate the causes of timber sleeper deterioration. Therefore, three methods of carbon fabric application for timber sleeper reinforcement, namely, carbon fabric-wrapped timber sleepers (CWT), one-layer carbon fabric timber sleepers with anchors (OCT), and two-layer carbon fabric timber sleepers with anchors (TCT), are studied and compared with conventional timber sleepers (CTS). Modal analysis is performed to obtain the sleeper damping ratios, and three bending moment tests are conducted to compare their load capacities. Furthermore, finite-element method (FEM) modeling is developed to compare the stress levels within each carbon fabric-strengthened sleeper. The bending moment test results indicate a high improvement in the load–displacement behavior of timber sleepers in the presence of carbon fabric, especially for the CWT, which shows a 55% improvement compared with the CTS, followed by the TCT and OCT, which show 50% and 33% improvements. Wrapped and two-layer and one-layer anchored systems have damping ratios of 0.21, 0.26, and 0.18, respectively, which are higher than that of conventional timber sleepers, at 0.17. The FEM results show that the stress levels of the timber sleepers with carbon fabric-strengthened systems decrease compared to CTS. Finally, a desirability function is developed to select the optimum carbon fabric system based on the load–displacement behavior, damping ratio, and insertion loss, which indicates a two-layer carbon fabric reinforcing system.