This report describes experiments relating to deck plate joints in orthotropic bridge decks, under transverse bending. The investigation involved fatigue tests on full-size specimens, strain measurements under load and strain measurements on specimens containing simulated residual welding stresses. The main findings were that the joint is load-carrying and the most likely mode of failure is by crack propagation from the weld root through the throat under the action of a bending moment in the stiffener. As a result of the presence of tensile residual welding stresses at the weld root, applied stress ratio had little effect on the fatigue strength for weld failure. The presence of tensile residual stresses near the weld could transfer failure to the weld toe in the deck plate or stiffener. For given loading conditions, the fatigue strength of the joint was virtually the same for any of the failure modes experienced. The results obtained from specimens which failed in the weld were correlated with data in the literature in terms of the calculated stress range in the weld throat. The results form a basis for a design s-n curve which, for the available results, could be extended to lives of the order of 60 x 1000000 cycles.

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