Diagnosis of Risk on structural failure for deteriorated bridge beams

In this paper the risk on structural failure of some heavily deteriorated bridges constructed with post-tensioned prefabricated T-girders is described. The bridges have undergone three detailed inspections with an interval of approximately five years. All visual deterioration was recorded and classified. To check the actual state of corrosion, at four viaducts with severe deterioration, the risk of corrosion of the prestressing bars has been thoroughly assessed. With high pressure water-jetting the anchorages of the prestressing bars where carefully partly uncovered. Parallel to this for two of these viaducts thorough structural assessments has been carried out. For the other viaducts the risk on structural failure is determined by a specifically developed quick-scan-model. With this model the bridges are ranked with respect to the risk on structural failure. Depending on this risk, a solution for conserving these structures was proposed and a Design and Construct contractor was chosen to repair and conserve the structures.