Fatigue enhancement in complex U-rib to diaphragm welds via rib-surface-bonded CFRP plates: Performance evaluation and configuration design

U-rib to diaphragm welds in orthotropic steel decks (OSDs) experience mixed-mode fatigue cracks and exhibit a more intricate stress state compared to the well-studied deck to U-rib welds. To mitigate the failure risks associated with such cracks, an investigation was conducted into a strengthening method using externally bonded carbon fiber-reinforced polymer (CFRP) plates through extensive fatigue experiments and numerical simulations. Three large segmental OSD specimens were tested to evaluate fatigue behavior, as well as stress indicators and crack growth rates before and after strengthening. Complementing the experimental results, validated multi-scale numerical models were established to provide further insight into stress intensity factors. This study demonstrated the effectiveness of the strengthening method and thoroughly investigated the influences of various strengthening parameters. A three-step method for determining the optimal strengthening configuration was also proposed, aiming to maximize both structural safety and the probability of crack arrest. The findings presented in this study contribute to our understanding of fatigue behavior in OSDs and provide valuable guidance for the design and application of CFRPs in bridge maintenance.