Experimental investigation into the size effect of bidirectional fiber patch anchors in strengthening of concrete structures

The strengthening of existing reinforced concrete structures using fiber reinforced polymers (FRP’s) as externally bonded reinforcement is gaining increasing attention due to the materials superior mechanical properties and light weight. However, a serious limitation in the use of FRP as a strengthening material comes from separation of the FRP from the concrete surface by premature debonding at a strain level which is well below the ultimate tensile strength of the material. A logical means to improve the performance of externally bonded FRP by mitigating the processes of debonding is by the provision of end anchorage. Of the many anchorages investigated by researchers, the use of bi-directional fiber patch anchors has shown exceptional promise. Due to the limitations of experimental data in this area, the current paper presents the first comprehensive experimental program into the size effect FRP patch anchors.