Reliability of Composite Bridge Superstructures with Fatigue-Degraded Shear Connectors

This paper proposes a methodological framework for assessing the reliability indicators of steel-concrete composite superstructures, taking into account the incomplete composite action between girders and slab caused by the accumulation of fatigue damage in shear connectors. This study summarizes the results of previous research by the authors, consolidating solutions to individual problems into a unified methodology aimed at predicting structural reliability indicators over time. Within this framework, 7 key tasks were identified: development of a model for the fatigue-induced degradation of the shear stiffness of connectors (task A); implementation of an iterative analysis of the finite element model with parametrized connector stiffness (B); development of a probabilistic model of the actual traffic load (C); calibration of the fatigue load model (D); determination of the optimal load cycle cluster size for model updating (E); tasks related to the optimization of reliability analysis (F and G). Recommendations for the most optimal solution are provided for each task. To demonstrate the applicability of the methodology, the paper includes a case study illustrating the implementation on a simple span example superstructure. The methodology can be used both for forecasting the reliability of newly designed structures and for assessing the condition of existing bridges.