Behavior of Shear-Critical Reinforced Concrete Beams Strengthened with Fiber-Reinforced Polymer-Analytical Method

Test specimens from a study on shear-critical reinforced concrete (RC) beams strengthened using fiber-reinforced polymer (FRP) wraps were found to be poorly predicted using FRP design formulations from CAN/CSA S6-06 and ACI 440.2R-08, which resulted in overpredicted FRP debonding failures and underpredicted rupture failures. In addition, some specimens reached FRP failure after the occurrence of flexural yielding, which is beyond the scope of current shear design provisions. An analytical method is presented to predict the load-deformation response of FRP strengthened beams, thereby determining ductility and accounting for shear failures that occur after flexural yielding. This paper also presents revised FRP strain limits for design based on developed theoretical expressions for debonding behavior. Presented strain limits for closed wraps account for both direct tensile rupture within the web and reduced rupture strain at the wrapped beam corners.