Behavior of corroded reinforced concrete columns with carbon fiber reinforced polymer jackets and columns with internal glass fiber reinforced polymer spirals

This research evaluated both corroded and noncorroded reinforced concrete (RC) columns in axial compression. Carbon fiber reinforced polymer (CFRP) jackets were shown to successfully rehabilitate severely corroded steel RC columns subjected to axial compression by doubling the compressive strength and quadrupling the axial strain at peak load of the noncorroded control specimens. Current design and analytical FRP confined concrete models were implemented and were found to compare well with experimental results. The closest predictions were obtained when accounting for additional confinement provided by the internal steel spiral. Other internal reinforcing including hybrid, which is a combination of vertical steel with a GFRP spiral , and all-GFRP RC columns were also tested in axial compression. This is the first time a GFRP spiral has been tested to my knowledge. An evaluation of the corrosion rates showed that the hybrid RC specimens corroded at less than 1/3 the rate of the all-steel RC specimens. The hybrid RC specimens subjected to corrosion also had approximately double the axial strain at peak load of the corroded all-steel RC specimens and showed more ductility after peak load. Two field aged bridge columns that were in service for over 40 years, with 9 of those years rehabilitated with CFRP jackets, were tested for bond under 2,000 kip concentric and eccentric loads and the bond was maintained when the substrate had been the original concrete.