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



Dat Duthinh, M A. Starnes


Seven concrete beams reinforced internally with steel and externally with carbon fiber-reinforced polymers (FRP) applied after the concrete had cracked were tested under four-point bending. Results show that FRP is very effective for flexural strengthening. As the amount of steel increases, the additional strength provided by the carbon 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.
NIST Interagency/Internal Report (NISTIR) - 6830
Report Number


anchorage, beam, building technology, carbon fiber-reinforced polymers, ductility, flexure, FRP, reinforced concrete, strengthening


Duthinh, D. and Starnes, M. (2001), Strength and Ductility of Concrete Beams Reinforced with Carbon FRP and Steel, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed May 22, 2024)


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Created November 1, 2001, Updated June 2, 2021