An Evaluation of Anchorage Systems for Fiber-Reinforced Polymer (FRP) Laminates Bonded to Reinforced Concrete Elements

Abstract

Many studies have shown that fiber-reinforced polymer (FRP) laminates are an effective alternative for structural retrofit and repair of insufficiently reinforced concrete members; however, achieving the full tensile capacity of the externally bonded FRP is often very difficult. This is especially true when FRP is used on elements where there is inadequate length to develop the full tensile strength of the FRP laminate, leading to premature debonding failure. Anchorage systems attempt to mechanically restrain the FRP or improve the FRP-to-concrete bond, thus reducing the length required to develop its full design strength. Many types of anchorage systems have been tested by different investigators, but mixed and inconclusive results have been presented. Additionally, no evidence exists to show that one particular type of anchorage system is completely effective in developing the full tensile strength of FRP. The lack of conclusive results is exacerbated by the absence of a consistent testing procedure for evaluating anchorage strength and a system for categorizing the purpose of the anchorage system, despite the current design guide's recommendation that anchorage testing should precede the strengthening of a structure with FRP. An overview of previously tested anchorage systems is presented along with applicable testing procedures from existing literature. The limitations of each anchorage system are mentioned with respect to specific structural strengthening applications. The existing anchorages are then categorized according to their specific application to FRP anchorage, and the applicability of testing procedures to each anchorage category is discussed. Finally, the need for systematic testing is discussed and potential research topics are explored.