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Structural Capacity Analysis of Corroded Steel Girder Bridges

More than 9% of the bridges in the United States were labeled structurally deficient according to the 2017 American Society of Civil Engineers’ infrastructure report card. The main causes of bridge deterioration are repeated vehicular loads and adverse environmental exposure. The most dominant deterioration form for steel bridges is corrosion, which is characterized by the loss of metal area resulting in reduction of structural capacity. Corrosion in steel multi-girder bridges is common in cold regions because of the frequent use of deicing chemicals during the winter season as well as leakage caused by bridge joint damage. At times, the rust is serious enough to disconnect the web from the flanges of the girder. This poses significant concerns for load capacity especially at girder ends. The consequences of bridge failure can be disastrous. This research investigates the structural capacity of these corroded steel girders. The mechanical behaviors of deteriorated girders are studied by 3-D finite element models built in ABAQUS and by lab testing. Our analysis is focused on web area loss and web thinning due to corrosion, and their consequences for load capacity reduction. The effects of location, size, and shape of area loss on shear and web buckling resistance will be studied. Lab tests on steel girder models will be conducted to verify the results from finite element modeling. Based on our analysis and findings, a simple and dependable rating method to evaluate deteriorated steel girder bridges will be developed.