Moment-Curvature Behavior of Glass Fiber-Reinforced Polymer Bar-Reinforced Normal-Strength Concrete and High-Strength Concrete Columns

A numerical integration approach was developed to investigate the moment-curvature behavior of glass fiber-reinforced polymer (GFRP) bar-reinforred circular normal-strength concrete (NSC) and high-strength concrete (HSC) columns. The results obtained from the developed integration approach were validated with the experimental results of eight GFRP bar-reinforced circular concrete column specimens. Out of these eight specimens, four specimens were cast with NSC having a compressive strength of 37 MPa and four specimens were cast with HSC having a compressive strength of 85 MPa. A parametric study was carried out to investigate the e f fect of concrete compressive strength and GFRP longitudinal and transverse reinforcement ratios on the moment-curvature behavior of the GFRP bar-reinforced NSC and HSC circular columns under combined axial and flexural loads. The results of the parametric study indicate that increasing the concrete compressive strength or GFRP longitudinal reinforcement ratio leads to an increase in the bending moment capacity and a decrease in the ductility of GFRP bar-reinfOrred concrete columns. The confinement provided by the GFRP helixes (transverse rein forrement) improves both the bending moment capacity and the ductility of the GFRP bar-reinforced circular concrete columns. The improvement in the performance (bending moment and ductility) due to increasing the GFRP transverse reinforcement ratio was greater in the GFRP bar-reinforced NSC columns than in the GFRP bar-reinforced HSC columns.