Fatigue crack-propagation law of diaphragm-to-rib welded joint in steel bridge deck

The crack-growth characteristics at different lengths are diverse, while blind maintenance for cracks cannot achieve satisfactory arresting effect. By carrying out numerical simulation and fatigue tests of diaphragm-to-rib welded joint (DU) specimens, the crack-growth rates, morphology and stress state at the crack tip were explored. The crack-growth process was segmented and reasonable maintenance occasions for DU cracks were proposed. The result shows that the oblique DU crack is affected by in-plane shear under out-of-plane deformation of diaphragm, driving the crack to grow to the horizontal. The DU crack presents the three-stage characteristics of fast-slow-rapid growth with the approximate demarcations of 8 mm and 40 mm. It is recommended to carry out maintenance in the first two stages to avoid entering the third rapid-growth stage. Combined with the applicability of maintenance technologies, classified maintenance methods of ICR, drilling and bolt reinforcement were proposed for cracks in three stages, respectively.

Automated summary

In this study, the crack-growth characteristics at different lengths were investigated through numerical simulation and fatigue tests. Reasonable maintenance occasions and classified maintenance methods for diaphragm-to-rib welded joint cracks were proposed, which are of great significance for maintenance of such joints.