Review on bond properties between wood and fiber reinforced polymer

Retrofitting of existing ancient and modern timber structures has been an important project recently. And it triggers a need of excellent strengthening methods, so does the strengthening of newly built architecture. Traditional strengthening methods have shortcomings such as high costing and destroying the aesthetic of the structure, many of which can be overcome by means of using fiber reinforced polymer (FRP) composites. However, the behavior of FRP-to-wood systems has yet to be thoroughly researched compared with their FRP-to-concrete or FRP-to-steel counterparts. As FRP retrofitting and strengthening timber structures has a promising future, better understanding of their failure modes will enable more precise designs balancing safety and cost. Three of the most common FRP-to-wood systems in the literature are discussed in this paper, namely, the externally bonded reinforcement (EBR), the near-surface mounted (NSM) and the glued-in rods (GiR) techniques. Debonding of the FRP from the substrate is one of the most common failure modes, which exhibits the signif-icance of the interface bond between FRP laminates and wood. Hence, bond properties and behavior of FRP-to-wood composite systems are described, parameters influencing the composite action are summarized in this paper, previous works on the bond interface of FRP and timber element are reviewed and future topics are also suggested. This work can provide a reference for future research and engineering applications.