Increasing load rating of a deteriorated RC bridge using CFRP fabric

A two span Reinforced Concrete (RC) girder bridge in Oldham County, Kentucky, had extensive deterioration of concrete along with exposure and corrosion of reinforcing steel. The main areas of deterioration included the pier cap ends and the ends of the outside beams over the pier cap. The damage was primarily caused by deicing agents passing through the deteriorated joint between the two spans. In addition to the deterioration, the bridge had a load posting preventing heavy vehicles from traversing the bridge. A retrofit design was developed to strengthen the deteriorated areas and increase the beams’ load carrying capacity. A thick unidirectional carbon FRP fabric was applied to the bottom face of the RC beams to increase their flexural capacity. Triaxial carbon fabric was used to confine the pier cap ends following the repairs, and U-wraps of triaxial and uniaxial carbon fabric were used to increase the beams’ shear rating. The retrofit, carried out in accordance with the ACI and AASHTO codes and guidelines, extended the bridge’s service life and enabled heavy trucks and school buses to pass over the bridge. The retrofit proved the most economical option for the county government and caused limited traffic disruption, establishing retrofitting as a viable alternative to bridge replacement.