Prediction of Anchorage Failure for Reinforced Concrete Beams Strengthened with Fiber-Reinforced Polymer Plates

Reinforced concrete beams strengthened with externally bonded fiber-reinforced polymer (FRP) plates to the tension face can exhibit ultimate flexural strengths several times greater than their original strength. Delamination of the concrete cover (anchorage failure) due to stress concentrations that develop at the plate curtailments, however, may occur before the beam can achieve its enhanced ultimate flexural strength. This paper investigates the anchorage failure mode of FRP-strengthened reinforced concrete beams. An improved analytical procedure for calculating shear and normal stresses at the plate curtailment is presented. The analytical expressions are developed from linear elastic theory and statistical analyses of experimental results. The procedure is validated by comparisons with experimental results reported in the literature. Also presented are simplified, closed-form expressions for estimating the anchorage failure load for FRPstrengthened beams subjected to either concentrated or uniform loads.