Steel prestressed cored slab superstructures are a structural system commonly used for bridges in coastal North Carolina. However, due to the aggressive marine environment several of such bridges are in need of major repairs or replacement after being in service for little more than 40 years. In order to prevent the premature deterioration of future bridges, an investigation was conducted into replacing steel prestressed cored slabs with FRP prestressed cored slabs.
A research program was undertaken to design, manufacture, and test to failure full-scale cored slabs prestressed with carbon FRP (CFRP) and reinforced with glass FRP (GFRP) stirrups. Direct tension tests were conducted on the CFRP strands and GFRP bars to validate the manufacturers’ design values. Beam-end specimens were tested to comparatively evaluate the bond characteristics of the CFRP strand. Two 45-ft long CFRP prestressed cored slabs were tested in flexure, while two were 15-ft long and tested in shear. The concrete section and CFRP strand layout were designed to be similar to those of current steel prestressed cored slabs so that they may be cast using existing stressing beds at precast facilities familiar with the production of cored slabs. Test results of the experimental program were compared to the predicted performance and strength of the CFRP prestressed cored slabs relative to current design recommendations given in the current ACI 440 design guides. Direct comparison to control steel prestressed cored slabs ensured that the CFRP cored slabs would be a suitable replacement alternative.
