Abstract
Fatigue failure origin of out-of-plane gusset welded joints used for steel bridges is usually weld toe with high stress concentration. In this case the fatigue strength evaluation is carried out using nominal stress on main plate and the fatigue strength obtained from a lot of fatigue test data. Weld root also becomes originating point of fatigue failure in case that weld toe is finished. However a stress parameter and fatigue strength are still unknown in the case of root failure. In this study, the fatigue test data for root fatigue failure have been collected, and they are arranged using nominal stress on main plate, hot spot stress, stress at the reference point, and effective notch stress. The fatigue strength evaluation method using effective notch stress and stress gradient is proposed by using fatigue test data and parametric FE analyses.
