Test and analysis of plain and steel fiber high strength concrete beams reinforced with GFRP bars

In this study, the behavior of plain and steel fiber high strength concrete beams reinforced with GFRP bars was examined. A total of five plain and steel fiber reinforced high strength concrete beams with GFRP reinforcement were manufactured and tested under four-point bending. One beam was a control specimen constructed with plain concrete, while the other four specimens were steel fiber reinforced high strength concrete beams. In the experiments, the crack propagations, deflections, load capacities, and failure modes of the beams were observed. The experimental load versus deflection responses of the beams were obtained. Besides this, the effects of steel fibers on ductility, crack propagation and the flexural behavior of the beams were investigated. The results indicated that the inclusion of steel fibers had considerable effect on ductility and stiffness capacity of beams and the use of steel fibers reduced crack width and spacing. The tested beam specimens as well as high strength concrete beams reinforced with GFRP bars available in the literature were analyzed for their theoretical load capacities and load-deflection curves. The nonlinear stress-strain model suggested for plain and steel fiber high strength concrete was used in the analysis. The results indicated that increasing reinforcement ratio led to an increase in the ultimate load capacity. The flexural strength capacity enhanced by increasing the concrete compressive strength. The increase in the modulus of elasticity of GFRP bars resulted in an increase in beam capacity. The increase in reinforcement ratio caused a significant improvement in the strength of beams. Increasing a/d ratio reduced the load carrying capacity of the beams.