Fatigue Assessment of Full-Scale Retrofitted Orthotropic Bridge Decks

Abstract

Full-scale fatigue tests were performed on two retrofitted orthotropic bridge decks (OBDs). The retrofitting systems consist of adding a second steel plate on the top of the existing deck. The aim is to reduce the stresses at the fatigue-sensitive details and therefore extend the fatigue life of the OBD by stiffening the existing deck plate. Two retrofitting systems were studied. The bonded system consists of bonding a second steel plate to the existing deck by vacuum infusing a thin adhesive layer (2 mm) between the two steel plates. The sandwich system consists of bonding the second steel plate through a thick polyurethane core (15 mm). The aim of the study was to assess the fatigue performance of both retrofittings. No fatigue damage was detected in the retrofitting layers during fatigue tests after three million cycles of wheel load. The stresses close to the deck-plate-to-stiffener welds decreased by at least 55% when using the bonded steel plates system and 45% when using the sandwich steel plates system. Both systems proved to have sufficient fatigue life to withstand traffic wheel loads running on orthotropic bridge decks and help extend the fatigue life of the existing OBD.