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

An experimental study was undertaken to assess the performance of shear-critical reinforced concrete (RC) beams strengthened with externally bonded carbon fiber-reinforced polymers (FRPs). Fifteen large-scale beam specimens were tested in reversed cyclic three-point loading to simulate a seismic event. Specimens were designed to fail in shear with three variations of internal transverse steel reinforcement. For each variation, specimens were strengthened with different FRP configurations: U-wrap strips, U-wrap sheets, closed wrap strips, and closed wrap sheets. Testing showed that FRP strengthening was effective at improving shear performance, which was not adversely affected by reversed cyclic loading prior to the occurrence of flexural yielding, even when transverse steel yielded. Design codes CAN/CSA S6-06 and ACI 440.2R-08 were found not to accurately predict the FRP shear contribution of the test specimens, particularly for closed wraps when the design strain limit of 0.4% was applied.