Experimental and analytical behavior of short concrete columns reinforced with GFRP bars under eccentric loading

This paper presents experimental and analytical studies on short concrete columns reinforced with glass fiber-reinforced polymer (GFRP) towards characterizing compressive behavior GFRP bars. The experimental program consisted of fourteen 500 mm-long specimens with a square cross-section (150 × 150 mm) including nine GFRP reinforced (6#5) and five plain concrete specimens. The specimens were tested under concentric and eccentric compressive load up to failure. Three eccentricity to width ratios of 0.1, 0.2, and 0.3 were considered, where the eccentricities applied symmetrically at both ends of simply supported columns. The experimental program showed no crushing of GFRP bars at peak load and the corresponding strain did not reach 50% of their crushing capacity obtained from material test. In addition, an analytical model was developed and verified against the experimental test data. The model considered both material nonlinearity and geometrical nonlinearity. Using the model, a parametric study was performed on the effect of eccentricity, reinforcement ratio, and concrete strength, which confirmed the capability of GFRP bars to sustain high strains without reaching the compressive strain capacity of the bars. The study showed that GFRP bars can be considered as load bearing longitudinal reinforcement of concrete columns and ignoring their effect is not necessary.