Finite Element Study of Stability of Corroded Metal Culverts

The development and the use of finite element analyses in the 1970s and 1980s changed the nature of culvert assessment because they permitted consideration of the geometrical and material details of the burial condition, as well as the construction process, culvert geometry, and earth and vehicle loads. While these procedures have been used to study a wide range of new culvert and pipe structures, there has been little consideration of the structural deterioration that is precipitating most current infrastructure investments. This study therefore examines the influence of corrosion on the stability of corrugated steel culverts. Corrosion in the lower half of the structure is considered, including a range of losses in wall thickness and lateral extents. Changes in the factor of safety against yield are assessed as corrosion develops, as are changes in culvert resistance to buckling failure. For the five specific design cases considered, the governing design criterion was stability against yield, and the factor of safety against yield was found to decrease almost in proportion to wall thickness (when maximum wall thrust within the corroded zone was considered). This decrease occurred because the corroded metal culverts experienced little change in the distributions of thrust or moment as a result of local losses in wall thickness. While the results presented are purely theoretical, they provide a starting point for an appreciation of the influence of metal culvert deterioration and can guide future research, including physical test programs.