Performance of Two Anchor Systems for Externally Bonded FRP Laminates

Fiber-reinforced polymer (FRP) composite materials have been proposed and used for the upgrade of concrete-based transportation and civil infrastructure. This technology has been proven to be effective, but issues related to bond length, end anchorage, and premature peeling have been a concern when strengthening structures in flexure or shear. This study presents two different types of FRP-based anchor system, namely, a near surface mounted (NSM) end anchor and a spike anchor. Each has been tested in an attempt to prevent or delay the problems listed above. A total of 16 specimens were tested to failure to check the effectiveness of the end anchor system and 19 specimens were tested to check the effectiveness of the spike anchor system. The focus of the study is on the influence of 1) the location, groove size, and anchor bar size for the first system; and 2) the location and embedment of the spike anchors for the second system. Test results show that each of these systems is highly effective in increasing the capacity of the strengthened member by delaying delamination of the FRP material. Bond-dependent coefficients of 0.90 (Km) and 0.25 (Kv) are recommendedwhen using these anchors for flexural and shear strengthening applications, after comparing the experimental results with the design guidelines.