For welded bridge components, the knowledge of residual stresses induced by welding is essential to determine their effect on the fatigue life behavior resulting in optimal fatigue design and a better knowledge about the fatigue strength of these welded connections. The residual stresses of a welded component in an orthotropic steel bridge deck are determined with the incremental hole-drilling method. This method is specified by the American Society for Testing and Materials ASTM E837-13a and it can be used only when the material behavior is linear-elastic. However in the region of the bored hole, there are relaxed plastic strains present that can lead to significant error of the measured stresses. The hole-drilling procedure is simulated with three-dimensional finite element modeling including a simplistic model of plasticity. The effect of plasticity on uniform in-depth residual stresses is determined and it is concluded that residual stresses obtained under the assumption of linear-elastic material behavior are an overestimation. Including plasticity for non-uniform in-depth residual stress fields results in larger tensile and smaller compressive residual stresses. Larger tensile residual stresses cause premature fatigue failure. Therefore, it is important to take these larger tensile residual stresses into account for the fatigue design of a welded component.

No abstract

No abstract

Modern fatigue design in civil constructions is mainly limited to the use of S-N curves and the hypothesis of Palmgren-Miner, as described in design standards and Eurocode. While using the latter, the fatigue evaluation may be conservative, since the outdated S-N curves are compared to current construction technology and weld properties. This shortcoming has a direct influence on the current design of orthotropic steel decks. To increase the understanding of the fatigue behaviour, an improved analysing tool using linear elastic fracture mechanics and extended finite element model is proposed. As a result, thickness effects are evaluated for both the longitudinal stiffener and the deck plate. These calculations indicated that increasing the thickness of the deck plate and the longitudinal stiffener increases the fatigue life of the structure. However, the thickness should be limited to maintain the advantage of a lightweighted construction.

No abstract