Estimation of the residual bearing strength of corroded bridge girders using 3D scan data

Abstract

The main cause of structural deficiency in steel bridges is corrosion damage at girder ends caused by the leakage of bridge joints. This localized corrosion damage reduces steel girders’ bearing strength and affects bridge structures’ overall load-carrying capacity. Accurate estimation of the residual strength of corroded elements is critical for prioritizing repair projects and allocating funding and resources. However, due to the varied environment around the metal surface, corrosion damage on bridge girders is highly variable in severity and shape. The inspection results could vary greatly from inspector to inspector using the current methods. The accuracy of the inspection cannot be ensured. To address this limitation, this study proposes a methodology for creating a computationally efficient finite element (FE) model of a steel plate girder end with the exact representation of the geometry of the corroded region using 3D scan data. The point cloud data from a high-resolution structured-light 3D scanner is used to obtain geometric features such as plate boundaries, connectivity between plates, and thickness variations across plates. This information is used to automatically create a FE model of the damaged girder using shell elements. The applicability and accuracy of the proposed methodology were evaluated using the results from the load testing of a full-scale girder with corrosion damage. The agreement between the experimental and analytical failure mode, force–displacement relationship, and strain distribution on the plates demonstrated the accuracy of the method for estimating the residual bearing strength of plate girders with corrosion damage.