Physical Models For Predicting The Aging Of Mechanical Track Systems

Railway track systems are continuously subjected to complex mechanical loading conditions that progressively degrade their structural integrity over time. Among critical track components, bi-block sleepers – widely implemented in French high-speed networks – play a pivotal role in maintaining track stability and effectively distributing dynamic loads. Their distinctive design, consisting of two reinforced concrete blocks interconnected by a steel tie bar, requires specialized modeling approaches to accurately represent their mechanical behavior and interactions with adjacent track elements. This research presents an advanced multi-scale modeling methodology for assessing bi-block sleeper performance: computationally efficient global models simulate overall track response to moving loads, while high-fidelity 3D finite element models enable detailed investigation of localized stress concentrations, particularly in vulnerable reinforcement zones. The integrated framework combines these modeling scales to systematically evaluate fatigue damage progression, employing industry-standard techniques including rainflow cycle counting and Palmgren-Miner's linear damage accumulation rule. Material behavior is characterized according to the CEB-FIP Model Code (1990) provisions to ensure reliable remaining service life predictions. By bridging global dynamic response with local damage analysis, this approach provides valuable insights for infrastructure condition assessment and maintenance optimization. The proposed methodology evaluates how operational conditions, such as hanging sleepers or ballast voids, elevate reinforcement stress and accelerate fatigue, linking support defects to reduced sleeper life for condition-based maintenance.