Flexural and Shear Performance of Concrete Beams Strengthened with Fiber Reinforced Polymer Laminates

Fiber Reinforce Polymer (FRP) composites are a very promising alternative to the use of traditional materials and methods in the repair and strengthening of under-designed or deteriorating structures. While most results indicate that strengthening with FRP is very effective, the wide variety of testing techniques used among researchers make it very difficult to compare results. Objectives of this research were to gain a broader understanding of FRP's effects on the failure modes and performance of reinforced concrete beams, to investigate a variety of strengthening schemes, and to validate current design methods used for shear and flexural strengthening of reinforced concrete members. This was achieved by comparing a variety of FRP systems under similar conditions. The seventy-one specimens tested exhibited a variety of failure modes depending on the strengthening scheme, thickness of the laminates, and material (carbon or glass fibers). The beam failure modes showed strong dependency on the FRP thickness. As the thickness of the composite laminate increased, debonding or concrete shear failure dominated. The effectiveness of FRP reinforcement was studied as a function of FRP rigidity and the effective strains developed in the fibers.