Bridge deterioration is mainly caused by repeated traffic loads and adverse environmental exposure. According to the 2017 American Society of Civil Engineers' infrastructure report card, more than 9% of the bridges in the United States were labeled structurally deficient. For steel bridges, the most dominant deterioration form is corrosion, which is characterized by the metal area loss resulting in structural capacity reduction. Corrosion is very common in steel multi-girder bridges because of moisture exposure, leakage through bridge joints as well as the frequent use of deicing detergents during the winter season in cold regions. Over the years, the rust can be serious enough to disconnect the web from the flanges of the girder, which poses significant concerns for load capacity especially at girder ends. This research studies shear strength loss in deteriorated steel multi-girder bridges by 3-D finite element models built in ABAQUS. Our analysis is focused on web area loss and web thinning due to corrosion, and their consequences for shear and web buckling capacity reduction. Area loss will be modeled by removing materials from the web, and web thinning will be simulated by reducing the web thickness. The numerical models resemble real steel corrosion forms by changing the shape, size and location of the area loss. A load rating method will be proposed based on the analyses.
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