Flexural stiffness of high strength concrete beams reinforced with GFRP bars

Deflection behavior of high strength concrete (HSC) flexural members reinforced with glass-fiber polymer bars (GFRP) is investigated. Because serviceability plays a significant role in establishing design acceptance for GFRP reinforced concrete beams, accurate modeling of flexural stiffness is critical and the effect of influencing parameters must be considered. This study accounts for variations in reinforcement ratio (r) for HSC beams. Experimental results from twelve simply supported concrete beams reinforced with GFRP bars are compared with published deflection models to establish analytic accuracy. All samples have a shear-span-to-depth ratio of 9.4 and are overreinforced with respect to a balanced strain design. Results show that the ACI 318 and ACI 440 effective moment-of-inertia expressions greatly overestimate flexural stiffness, with the degree of inaccuracy dependent upon on reinforcement ratio.