Shear strengthening of RC beams with NSM FRP strips: Concept and behaviour of novel FRP anchors

The high efficiency of the near-surface mounted (NSM) fibre-reinforced polymer (FRP) technique for improving the shear capacities of reinforced concrete (RC) beams has been proved by numerous studies. However, premature debonding failures including interfacial debonding and concrete cover separation, which could largely limit the utilization of FRP strength, were frequently observed in RC beams strengthened in shear with NSM FRP. Proper anchoring measures of NSM FRPs can mitigate or even prevent such debonding failures and thus enhance the FRP strengthening efficiency, but relevant research on anchoring measures for NSM FRP shear-strengthened beams is still limited. Against the above background, a novel FRP anchor for NSM FRP shear-strengthened beams is proposed in this paper. A test program consisting of eight full-scale RC beams is carried out to investigate the effectiveness of the proposed FRP anchor system. It can be seen from the test results that the proposed FRP anchor is capable of mitigating or preventing the FRP debonding failures and thus significantly enhancing the load-carrying and deformation capacities of RC beams strengthened in shear with NSM FRP strips, and the configuration of the anchor can largely influence the performance of strengthened beams.