State-of-the-art of fatigue performance and estimation approach of orthotropic steel bridge decks

The structural service behaviors and fracture failures of orthotropic steel bridges are significantly depended on its anti-fatigue performance. Therefore, an urgent requirement is needed for a state-of-the-art summary of the fatigue failure mechanism and life evaluation is needed, to sort out research focuses and development direction, such as to establish the whole-life anti-fatigue theory of steel bridges. The fatigue failure mechanism of cracks observed at U-rib-to-deck joints is revealed with a higher appearance rate of 50.0 %, compared to U-ribs and U-rib-to-crossbeam joints. Fatigue cracks are validated to originate at weld toe or root of U-rib-to-deck joints, and propagated along the deck thickness direction. Then the fatigue performance of deck plates is improved using advanced techniques, such as steel jacketing and polymer rebars. A suitable S-N curve-based anti-fatigue design approach can be adopted based on the application scope, stress amplitude and joint types. Advanced techniques have been implemented to monitor the health state of steel bridge components, and detect the potential appearance of fatigue cracks. Further, the fatigue failure life of orthotropic steel bridges is extended by 1 to 12 times at most, and the fatigue strength of vulnerable positions is correspondingly reduced by 20 % to 80 %.