Development of a hybrid anchor to improve the bond performance of multiple plies of FRP laminates bonded to concrete

Fiber reinforced polymer composites (FRPs) are currently one of the leading materials used to strengthen reinforced concrete (RC) structures against various loading actions such as flexure, shear and torsion. Due to the escalating loads being applied to existing structures, significant structural deficiencies have resulted in higher strengthening demands on many projects, resulting in large and often impractical quantities of FRPs being needed to achieve the required level of strengthening. Although FRP possesses significant advantages over traditional materials in terms of strength, the phenomenon of premature debonding currently limits the degree of material utilization achieved in practice. One means by which debonding may be addressed is by the use of anchorage systems that facilitate the utilization of more layers of FRP prior to failure. The paper presents an experimental investigation of a new hybrid anchor, comprising of 3 layers of ±45° bidirectional fiber sheets used to anchor 2 plies of FRP laminate to the concrete. The patch anchor concept is further enhanced by anchoring the ±45° bidirectional fiber sheets to the concrete with FRP spike anchors, with the dowel end of the anchor embedded into the concrete and the fan end attached to the bidirectional fiber sheet. Significant improvements in the bond performance of the FRP laminates were observed as a result of the hybrid anchor.