Improvement of FRP-to-concrete bond performance using bidirectional fiber patch anchors combined with FRP spike anchors

Fiber reinforced polymer (FRP) composites have become the most widely used material to strengthen reinforced concrete (RC) structures when subjected to various loading actions. It has been demonstrated that the governing failure mode of FRPs when used as externally-bonded reinforcement is by premature debonding of the FRP material from the concrete substrate. Research has shown that FRP-to-concrete bond performance may be improved is to provide anchorage systems that resist the interfacial shear and peeling stresses that are generated in the FRP bond line. FRP spike anchors and bidirectional fiber patch anchors are a proven means to enhance the bond performance of FRP materials when bonded to concrete. Although these anchorage systems have shown significant promise when investigated independently, their combined efficacy has not been investigated. The present research aims to combine the unique properties of these two anchorage systems to form a hybrid anchorage system with superior strength properties. The results from an experimental program are presented, derived from FRP-to-concrete anchored joints, where FRP spike anchors were used to anchor bidirectional patches and used to restrain FRP laminates. All specimens demonstrated significant enhancements in the strength of the joints as a result of the hybrid anchor.