Crack growth prediction of deck plate-stiffener joints in orthotropic steel bridge decks

Orthotropic deck structures are used in many steel bridges. Due to the typical detailing applied as around 1970, a significant number of deck structures constructed in that period suffer from fatigue damage. In many countries cracks have been detected, in particular in the weld between the deck plate and the trapezoidal stiffener. These cracks tend to grow relatively slowly, but are difficult to detect in an early stage because they initiate from inside of the trapezoidal stiffener. This paper presents a model with which the growth of these cracks can be predicted. The model is aimed at the growth rate prediction of through-thickness cracks that can be detected by visual inspection. Stresses are extracted from a detailed finite element model of the entire deck. A second, local finite element model including the crack is used as the basis of a fracture mechanics model. The growth rate determined with the model is calibrated and validated with measured cracks in various bridges.