Large-size reinforced concrete columns strengthened with carbon FRP: Validation of existing design guidelines

Current international design guidelines provide predictive design equations for the strengthening of Reinforced Concrete (RC) columns of both circular and prismatic cross-sections by means of FRP confinement and subject to pure axial loading. Extensive studies (experimental and analytical) have been conducted for the case of columns with cross-sections of the circular type, and limited studies have been conducted on the prismatic ones. In fact, the majority of this research has been on small-scale, plain concrete specimens. In this review paper, four international design guidelines are referenced, and a comparative study is presented that is based on the increment of concrete compressive strength and ductility and that, includes the experimental results from six RC columns of different cross-section shapes. The observed outcomes are used to identify and remark upon the limitations beyond the ones specifically stated by each of the guides and to reflect the absence of effects not considered in current models. The purpose of this study is to present a constructive critical comparison of the state-of-the-art design methodologies available for the case of FRP-confined concrete RC columns and to indicate a direction for future developments.