Behavior and modeling of fiber reinforced polymer-confined concrete

One important application of fiber reinforced polymer (FRP) composites in the retrofit of reinforced concrete structures is to provide confinement to columns for enhanced strength and ductility. As a result, many theoretical and experimental studies have been carried out on FRP-confined concrete. This paper provides a critical review of existing studies, with the emphasis being on the revelation of the fundamental behavior of FRP-confined concrete and the modeling of this behavior. Aspects covered in this paper include stress-strain behavior, dilation properties, ultimate condition, and stress-strain models. The paper concludes with a brief outline of issues which require further research. Although the paper is explicitly limited to concrete confined by FRP jackets in which the fibers are oriented only or predominantly in the hoop direction, many of the observations made in this paper are also applicable or relevant to concrete confined by FRP jackets with a significant axial stiffness, as found in concrete-filled FRP tubes as new columns.