Analytical calculation of internal forces in orthotropic plated bridge decks based on the slope-deflection method

Orthotropic plated bridge decks are highly sensitive to fatigue damage, due to the large amount of welded connections, the high patch loads and the large number of stress cycles they involve. For highway bridges, the stiffener web to deck plate weld is often the determining fatigue detail for the deck design. This paper develops a detailed analytical model for the stresses in this detail, using the slope-deflection method. It models a cross-section of the deck plate, but incorporates into it the influence of the horizontal and vertical stiffness of the entire orthotropic plate as well as the torsional rigidity of the longitudinal stiffeners. This calculation method allows for the determination of all internal forces of the determining cross-section of the bridge deck.