Performance Evaluation of Glass Fiber-Reinforced Polymer Shear Reinforcement for Concrete Beams

Using fiber-reinforced polymer (FRP) reinforcing bars as the main reinforcement for concrete structures in severe environments is becoming a widely accepted solution to overcome the problem of steel corrosion and the related deteriorations. Due to the relatively lower cost of glass FRP (GFRP) bars compared to the other commercially available FRP bars, the use of GFRP bars in reinforced concrete (RC) structures has been widely investigated in the last few years. This paper reports experimental data on the shear strength of concrete beams reinforced with GFRP stirrups. A total of four large-scale RC beams with a total length of 7000 mm (276 in.) and a T-shaped cross section were constructed and tested up to failure. The test variables were type and ratio of shear reinforcement (stirrups). The test beams comprised three beams reinforced with sand-coated GFRP stirrups of 9.5 mm (3/8 in.) diameter spaced at d/2, d/3, and d/4 (where d is the beam depth), and a reference beam reinforced with conventional steel stirrups of 9.5 mm (3/8 in.) diameter spaced at d/2. As designed, the beams failed in shear due to GFRP stirrup rupture or steel stirrups yielding. ACI 440.1R-06 and the updated version of CAN/CSA S6-06 are able to predict the shear strength of beams reinforced with GFRP stirrups with a reasonable accuracy. The analytical approach using Response 2000 (R2K), which is based on the modified compression field theory (MCFT), predicted well the shear capacity of the beams reinforced with GFRP stirrups, but overestimated their shear crack width.

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