A strain-based index for monitoring laminates of FRP-strengthened beams

Carbon fibre reinforced polymer (FRP) laminates are increasingly being used to strengthen reinforced concrete beams. Monitoring the integrity of the adhesive bond between the laminate and the concrete is important to establishing the long-term reliability of this technique. This paper discusses the development of a strain-based index in which the loss of strain compatibility can be used to identify regions where debonding has occurred. Theoretical and experimental work was conducted and the laminate tensile strain profiles were shown to be sensitive to the presence of induced debonded zones. The method has potential for broad implementation in many field monitoring applications.