FRP-to-concrete joint assemblies anchored with multiple FRP anchors: experimental investigation

Higher strains can be developed in fibre-reinforced polymer (FRP) composites which are bonded to the surfaces of concrete members if the FRP is anchored. Anchors made from FRP (also known as FRP spike anchors but herein referred to as FRP anchors) are a promising type of anchorage as they can be applied to a variety of different shaped structural elements and they have been shown to be effective in enhancing the strain capacity of externally bonded FRP. Limited research, however, has been conducted on understanding and quantifying the strength and behaviour of such anchors in isolation and research to date has been on mainly single anchors. A series of tests is therefore reported in this paper on FRP-to-concrete joints anchored with two FRP anchors with the main test variable being the relative position of the anchors. Displacement controlled tests have enabled the complete load-slip responses of the joints to be captured which in turn provides valuable insights to be gained in understanding the behaviour of the anchored joint over the complete loading range. The tests reported in this paper advance our understanding of FRP anchor groups in anchoring externally bonded FRP strengthening systems.