Shear Behavior of Variable-Depth Concrete Beams with Wound Fiber-Reinforced Polymer Shear Reinforcement

A novel shear reinforcing system, wound fiber-reinforced polymer (W-FRP), that capitalizes on the flexibility of carbon fiber to create durable reinforcement cages for geometrically optimized concrete structures, is proposed thereby unlocking new potential to minimize carbon emissions associated with new concrete structures. Fiber-reinforced polymer (FRP) shear design methods have been extensively validated against prismatic beam tests, but variations in geometry have not yet been considered. This paper proposes revised design methods, validated using tests of eight W-FRP-reinforced variable-depth concrete beams, to examine the contributing factors to shear capacity. The corner strength, orientation, and compression concrete confinement provided by W-FRP links, along with the contribution to shear of longitudinal bars, are shown to be key design parameters. Optimizing the W-FRP pattern is found to enhance shear capacity by as much as 50%. The variable-depth geometry tested in this paper uses 19% less concrete than an equivalent-strength prismatic beam. Both reinforcement and geometry optimizations are the key steps toward achieving minimal material use for concrete structures.