Experimental Evaluation of Slender High-Strength Concrete Columns with GFRP and Hybrid Reinforcement

The behavior of slender high-strength concrete columns reinforced with glass fiber-reinforced polymer (GFRP) bars and spirals subjected to concentric and eccentric axial loads was evaluated. Large-scale tests were conducted for nine circular concrete columns (three short and six slender) reinforced with internal GFRP-spirals and either steel, GFRP, or a combination of steel and GFRP longitudinal bars. The short and slender columns had slenderness ratios equal to 10 and 49, respectively. Axial load tests were conducted with loads placed concentrically (short columns) and at two eccentricities (slender columns) to observe the general behavior associated with different geometric and loading conditions. The behavior of slender columns with small eccentricity (8.3% of the column size) was governed by material failure, while that of slender columns with large eccentricity (33% of column size) was governed by a buckling failure. The research shows that GFRP spirals and GFRP longitudinal bars are a viable method of reinforcement for slender concrete columns subjected to eccentric axial loads. (C) 2016 American Society of Civil Engineers.