Examination of local stresses in relation to fatigue failure at the rib to floorbeam joint of orthotropic plated bridge decks

Abstract

A substantial number of orthotropic decks suffer from fatigue-related problems, which can be attributed to increase in traffic loads, bad detailing, or lack of understanding of the mechanisms leading to these problems. Of the various fatigue-prone locations, the rib to floorbeam joint is the most challenging, since it is subjected to a complex set of in- and out-of-plane stresses. In this paper, the case of continuous longitudinal ribs passing through the floorbeam web by an additional cope hole is addressed. In such a configuration, the first fatigue crack initiating at the joint can either grow in the floorbeam web or in the rib walls, depending on the geometric conditions. Both situations are addressed in the paper, providing a parametric study of distortion-induced rib stresses as well as a simplified method for cutout stress calculations.