Secondary Stresses in Closed Orthotropic Deck Ribs at Floor Beams

Abstract

Analysis is made of the secondary flexural stresses in the walls of trapezoidal orthotropic steel deck ribs at the top of the floor beam web cutouts. These stresses are due to the transverse expansion of the bottom portions of the ribs caused by the Poisson's ratio effect of compressive longitudinal stress. In combination with primary stresses, they can be an important contributing factor in the development of fatigue cracks. Yet, they have been overlooked in previous investigations. The secondary stress formulas are functions of the primary rib stress and the geometry—width of the rib bottom, rib‐wall thickness, radius of rib corner curvature, and the depth of floor beam cutout. The stress is inversely proportional to the square of the cutout depth, and, therefore, the cutout should be made as deep as practicably possible. Formulas for the maximum values of secondary stresses are illustrated by numerical example. Additional recommendations for minimizing stress raisers at the junction are also made.