System reliability analysis of CRTS III track slab considering multiple failure modes.

Under train loads, temperature loads, and subgrade deformation, CRTS III track slabs may experience various failure modes such as longitudinal bending, transverse bending, steel yielding, and fatigue damage. To explore the system reliability of CRTS III track slabs under various failure modes, this study is based on analytical expressions and finite-element techniques. The load effects on track slabs were calculated, and the limit state functions corresponding to different failure modes of track slabs were analyzed. To perform series system analysis of various failure modes, and establish dimensionless limit state functions, eight different load combination forms are generated. Reliability considering individual failure modes and system reliability of track slabs are analyzed using the method of moments. Results show that combined load effects in the same direction are more likely to cause track slab failure. For instance, under the combined action of negative temperature gradient and subgrade settlement, the reliability of longitudinal bending is β = -0.2536, which is seriously unsatisfactory for meeting safety requirements. Conducting an independent analysis of individual failure modes would overestimate the reliability of track slabs, thus emphasizing the necessity of analyzing the system reliability of the track slabs.