Influence of the anchor fan position on the performance of FRP anchors

Abstract

Fibre-reinforced polymers (FRP) are broadly employed for structural retrofitting, both as external and near-surface mounted reinforcements. Externally bonded plates are easy to apply and offer significant flexibility of design; however, premature debonding from the substrate hinders optimization of these reinforcements. In the last decade, several anchorage techniques have been developed to delay or prevent delamination of externally bonded FRP. Among these techniques, anchors made of carbon or glass fibres (FRP anchors) guarantee durability and compatibility with both substrate and reinforcement. Installation parameters affect the performance of FRP anchors and determine their maximum load. This paper presents experimental results concerning installation parameters of carbon fibre anchors; FRP-to-concrete shear tests were conducted regarding the relative position of anchor fan and reinforcement. Three different configurations were tested and compared to an unanchored control series. The results show that the relative position of the anchor fan had great influence on maximum load, load-displacement relationship and failure load; the best performance was achieved by specimens with the anchor fan between plies; the installation of anchors piercing the reinforcement allowed increased the maximum load but caused stress concentration around the insertion point; anchors placed under the reinforcement were not able to avoid debonding, although they increased the failure load when compared to unanchored specimens.