Fatigue behaviour of rib-to-deck welded joints based on European standard fatigue loading models

Fatigue damage in orthotropic steel decks (OSDs) is a critical concern for bridge safety and service life. Current standards, such as the Eurocode, often provide fragmented and non-exhaustive guidance for fatigue load modelling, particularly for complex weld details like the trapezoidal rib-to-deck connection. This study systematically investigates the influence of the fatigue load models (FLMs) specified in the European standard on the stress response and predicted fatigue life of this critical connection. Using finite element models of real medium- and long-span OSD bridges, the analysis quantifies the impact of: (a) local versus global load effects, (b) point load versus realistic tyre contact patch modelling, and (c) crossbeam stiffness. The results demonstrate that these factors significantly influence the calculated stress ranges and subsequent fatigue life predictions calibrated with real traffic data, providing engineers with critical insights for more accurate and reliable fatigue assessment. The results show that modelling the tyre contact patch instead of point loads leads to a stress reduction ranging approximately from 36% to 65%, significantly affecting fatigue life predictions.