John T. McNaughton Bridge Rehabilitation

Orthotropic bridge decks are a bit of a dichotomy. Unlike conventional reinforced concrete bridge decks, steel plate with a thin protective wearing surface is used to bear the brunt of roadway traffic. But if the plate is designed too flexible, the protective surface may begin to crack, exposing the steel deck to water and other harmful agents. This was the case with the McNaughton Bridge. It was a common problem, but one with few instances of successful abatement. 

 

An advanced state of corrosion had developed on the top of the McNaughton Bridge steel deck plate. To combat the problem, our technical experts performed an initial review and investigation of the long span girder bridge. This included an evaluation of replacement overlays for rehabilitation. Next, Modjeski and Masters identified a solution for final design. The fix: to replace the deteriorating wearing surface with a layer of fiber-reinforced concrete. Fiber reinforcement improves concrete’s resistance to cracking and, therefore, minimizes water infiltration. Along with a layer of reinforcing bars, shear studs were used to unite the new layer with the existing steel deck plate. Construction of the new robust deck was completed in 2002, and continues to serve today, without the cracking.