Proposed Slenderness Limit for Glass Fiber-Reinforced Polymer-Reinforced Concrete Columns Based on Experiments and Buckling Analysis

To develop design provisions for concrete columns reinforced with fiber-reinforced polymer (FRP) bar for North American codes and guidelines (ACI 440.1R, CSA S806), a slenderness limit below which it is acceptable to ignore the induced second-order effects must be determined. Nevertheless, limited attempts have been made to define a safe slenderness limit for such columns. Therefore, this study aimed at experimentally and analytically investigating the buckling behavior of 12 full-scale concrete columns reinforced with glass FRP (GFRP) with slenderness ratios of 14, 17, 23, 26, and 33 under concentric loading. The impact of longitudinal rein-forcement ratios and confining levels on the performance of slender GFRP-reinforced concrete (GFRP-RC) columns is also presented. Test results indicate that the GFRP reinforcement contributed significantly to resisting the applied compression loads and resulted in failure modes similar to that of the counterpart steel-reinforced concrete columns at different slenderness ratios. In addition, a theoretical buckling analysis considering a total of 50 test specimens, assembled from the current study and the literature, was developed to verify the applicability of Euler-Johnson's stability envelope as well as the reduced and incremental modulus theories to FRP-RC columns. Good correlation was observed between the experimental results and the models developed analytically. Based on the experimental data and the developed buckling analysis, the safe limit of the slenderness ratio for FRP-RC columns bent in single curvature of 18 is proposed.