Strength and Behavior of Circular FRP-Reinforced Concrete Sections without Web Reinforcement in Shear

Considerable experimental research work has been conducted to quantify the shear strength Vcf of rectangular concrete members reinforced with fiber-reinforced polymer (FRP) bars. In contrast, no research seems to have investigated circular concrete members reinforced with FRP bars under shear loads. This paper reports on a study on the behavior and shear strength of full-scale circular concrete beams reinforced with longitudinal FRP bars. The beams, which measured 3,000mm in length by 500mm in diameter, were tested under four-point bending. The test parameters included the longitudinal reinforcement ratio and the modulus of elasticity of the reinforcing bars. Steel, glass-FRP, and carbon-FRP bars were used in the experimental program. The experimental results were compared with current codes and design guidelines as well as to recently developed shear design equations appearing in the literature. The comparison indicates that the shear capacity of FRP-reinforced concrete members with circular cross sections may be determined with the Vcf approaches developed for rectangular sections provided that certain modifications are made to take into account the effective shear depth and equivalent breadth. (C) 2016 American Society of Civil Engineers.