Influence of FRP anchors on the strength and ductility of FRP-strengthened RC slabs

Extensive experimental verification has shown that existing reinforced concrete (RC) members can be strengthened with externally bonded fibre-reinforced polymer (FRP) composites. Two well documented limitations to the strengthening technology though are premature FRP debonding failure and non-ductile member behaviour. A recent study by Smith et al. [1] showed anchors made from FRP (also known as FRP anchors) to be effective in delaying debonding and also effective in enhancing the deformability (and ductility) of RC slabs strengthened in flexure with FRP plates. This paper extends the work of Smith et al. by reporting the results of tests on 10 FRP-strengthened RC slabs anchored with FRP anchors of varying geometry and positioning. Optimal arrangements of anchors in this second series of tests have enabled the load and deflection capacities of the FRP-strengthened slabs, in relation to the unanchored but strengthened control slab, to be enhanced by up to 44% and 216%, respectively. Strain utilisation of the FRP plate has also been shown to increase from 44% of the flat coupon strain capacity for the unanchored but strengthened control slab to 95% for an optimally anchored FRP-strengthened slab.