Full-Scale Testing of CFRP-Strengthened Slender Reinforced Concrete Columns

The paper presents an investigation into the performance of slender rectangular reinforced concrete columns strengthened with carbon fiber-reinforced polymers (CFRPs) in two manners. The first approach is a well-known form of CFRP sheet jacketing with the effect demonstrated in many studies, and a second one is a relatively new retrofit method of near surface mounted (NSM) CFRP strips. A total of eight full-scale specimens with rectangular cross sections ($210\times 150\mathrm{mm}$) were tested to failure under eccentric compressive loading. The total length of the specimens was 4,100 mm. The results of this study demonstrate a significant difference in slender and short column strengthening in accordance with the predominant stress manner. It was confirmed that the effect of CFRP wraps on the increase in column strength is proportionally greater for short RC columns subjected to predominant compression. The longitudinal fibers in CFRP strips bonded into grooves in concrete cover are more effective in enhancing the flexural load-carrying capacity of slender reinforced concrete columns subjected to eccentric loading. The most effective approach to flexural capacity enhancement was demonstrated by a synergistic effect of NSM CFRP reinforcement ensured by CFRP sheet wrapping.