Strength and Ductility of Concrete Beams Reinforced with Carbon FRP and Steel

摘要

Seven concrete beams reinforced internally with varying amounts of steel andexternally with carbon fiber-reinforced polymer (FRP) laminates applied after the concrete had cracked under service loads were tested under four-point bending. Strains measured along the beam depth allowed computation of the beam curvature in the constant moment region. Results show that FRP is very effective for flexural strengthening. As the amount of steel increases, the additional strength provided by the carbon FRP laminates decreases. Compared to a beam reinforced heavily with steel only, beams reinforced with both steel and carbon have adequate deformation capacity, in spite of their brittle mode of failure. Clamping or wrapping of the ends of the laminate enhances the capacity of adhesively bonded FRP anchorage. Design equations for anchorage, allowable stress, ductility, and amount of reinforcement are discussed.