Flexural behavior of CFRP-strengthened and end-anchored RC beams with large fiber anchors

This paper presents an experimental study on the flexural strengthening of RC beams using externally bonded CFRP sheets combined with carbon fiber anchors to prevent premature debonding and improve flexural capacity. Ten RC beams were externally strengthened with CFRP and anchored with different configurations of carbon fiber anchors. The behavior of the beams with anchors was compared to the behavior of a control beam without anchors and to a benchmark beam without strengthening. The anchor parameters tested in this experimental program include CFRP anchor diameter, embedment depth, fan length, and fan angle. The response of the tested beams was analyzed and discussed in terms of failure modes, load-deflection curves, flexural strength, ultimate strain in the CFRP laminates, and ductility. Test results showed that the application of end-anchorage can significantly enhance the flexural performance of CFRP-strengthened RC beams, increasing the ultimate load-carrying capacity and improving the beams behavior at failure. The anchored beams exhibited increases in ultimate load-carrying capacity ranging from 7 % to 32 %, with the highest improvements observed for beams with larger anchor diameters (24 mm). The study also highlights the need for prediction models to account for anchor contributions and calls for further experimental research to improve the reliability of design guidelines. These findings show that anchoring CFRP sheets effectively prevents premature debonding and ensures that RC beams can safely achieve higher flexural capacities and ductility in practice.