Debonding Failure in FRP Reinforced SHCC Beams Induced from Multiple Flexural-Shear Cracks under Three-Point Bending Test

Strain hardening cement-based composites (SHCC) beam externally bonded with glass fiber-reinforced polymer (FRP) plate was examined under three-point flexural test. The effects of the type of substrate used (plain cement mortar vs. SHCC), the use or not of a FRP plate to strengthen the SHCC beam, and the thickness of the FRP plate on the flexural performances were studied. Results show that the ultimate load of SHCC beams strengthened with FRP plate has improved greatly in comparison with plain SHCC beams. The deformation capacity of beams makes little change with an increase in the thickness of FRP plates. The formation of multiple flexural-shear cracks (MFSC) is the unique feature of SHCC beams bonded with FRP plates under three-point bending. The debonding of the FRP plate is initiated from MFSC. The initiated debonding area (IDA) is formed by the joint points of the flexural-shear cracks with the FRP plate. Then the debonding strain is represented using the average strain of FRP plate within IDA, which decreases with an increase of FRP plate thickness. The experimental values of the debonding strain of SHCC beam reinforced with FRP plate are close to those predicted by the JSCE?s equation.