Effect of Fiber-Reinforced Polymer Configuration on Reliability of Flexurally Strengthened Concrete Beams

Abstract

External bonding of composite materials in the form of strips, plates, and laminates to add tensile capacity in deficient zones has proved to be an efficient strengthening technique. The performance of composite materials in strengthening ailing infrastructure components has made them a mainstream alternative in some applications such as strengthening concrete structures. The technique is mature enough that design standards have been published. Few researchers have investigated the reliability of concrete structures strengthened with fiber-reinforced polymer (FRP). The results of these reliability investigations were incorporated in some of the recently published design guidelines. It is a well-known fact that FRP debonding is the dominant mode of failure. Nevertheless, the impact of different FRP configurations on the reliability of strengthened concrete beams in flexure has not yet been investigated. An analytical study is presented of the reliability of FRP-strengthened concrete beams in two of the most popular configurations: U-wrap and soffit-only. Material, fabrication, and model uncertainties are accounted for in a strength limit state function to analyze the reliability of strengthened reinforced concrete beams by using the first-order reliability method. Results from this study show that the reliability of U-wrap configurations is higher than that of soffit-only configurations. This finding can be used in establishing different resistance factors for each case such that the use of more materials in the U-wrap configuration is rewarded by the ability to predict its performance better.