Study on the Influence of Anchorage Configuration on the Flexural Performance of CFRP-Reinforced RC Beams

Carbon fiber reinforced polymer (CFRP) has been widely used to strengthen reinforced concrete (RC) beams because of its high strength, light weight, corrosion resistance, and convenient construction. CFRP sheets can effectively improve the flexural capacity of RC beams. However, premature debonding between the CFRP sheet and the concrete surface often occurs during loading. This problem limits the full utilization of the tensile strength of CFRP. Effective end anchorage is therefore required to delay or prevent debonding and to ensure better stress transfer. In this study, four-point bending tests were conducted to investigate the influence of different end anchorage methods on the flexural performance of CFRP-strengthened RC beams. Several beams were designed and tested under monotonic loading. The crack development, failure modes, load–deflection responses, and strain distributions were recorded and analyzed during the loading process. The behavior of unstrengthened beams was also compared with that of strengthened beams. The experimental results show that the use of end anchorage can significantly improve the cooperative behavior between the CFRP sheet and the concrete substrate. Both U-wraps and carbon fiber bundle anchors effectively restrained crack propagation and delayed the debonding of CFRP sheets. These anchorage methods also changed the failure mode of the strengthened beams and allowed the CFRP sheets to participate in the load-carrying process for a longer period. As a result, the strength utilization of the CFRP sheets was improved. Compared with the unstrengthened beam, the ultimate load of the beams anchored with U-wraps and carbon fiber bundle anchors increased by 35.2% and 42.3%, respectively. The maximum strain decreased by 12.5% and 31.3%. The results indicate that the carbon fiber bundle anchor provides a more uniform stress distribution in the CFRP sheet. It also shows the most significant improvement in the flexural performance of the strengthened beams. The findings provide useful guidance for the design and application of end anchorage methods in CFRP-strengthened RC beams.