Review of Current Design Guidelines for Circular FRP-Wrapped Plain Concrete Cylinders

With the widespread use of fiber-reinforced polymer (FRP) composites in the construction sector as a strengthening technique, the development of design guidelines for the field application of externally bonded FRP systems is ongoing in Europe, Japan, Canada, and the United States. The main goal of this study is to evaluate the current seven international design guidelines and four other design models for the prediction of confined concrete compressive strength of FRP-wrapped plain concrete cylinders against the experimental results of a large database of 812 specimens reported in the literature. The results clearly show that the reliability of predictions of confined concrete compressive strength of FRP-wrapped plain concrete cylinders by the design guidelines significantly varies for different ranges of unconfined concrete compressive strength. For example, the gain in confined concrete compressive strength of FRP-wrapped low- and medium-strength concrete cylinders is larger than that of high- and ultrahigh-strength concrete cylinders. Furthermore, a simplified model for the prediction of design/characteristic–confined concrete compressive strength is developed based on the design-assisted-by-testing approach. The developed simplified model accounts for the variation in confinement effectiveness for different ranges of unconfined concrete strengths.