Shear Behavior of Reinforced High-Strength Concrete Beams

This paper describes the shear behavior of reinforced high-strength concrete (RHSC) beams (f(c)' > 100 MPa [14,500 psi]) without web reinforcement. The use of high-strength concrete (HSC) has led to some concerns about its shear strength because of its brittleness, smooth fracture surface, and high early-age shrinkage. Test results indicated that the ratio of uniaxial compressive strength to tensile strength (the ductility number) of the concrete relative to that of the aggregate governs the shear strength of HSC. When the ductility number of the concrete coincided with that of the aggregate, the shear strength remained constant, irrespective of concrete strength. When the ductility number of the concrete was higher than that of the aggregate, however, shear strength started to decrease due to the smooth fracture surface and brittleness. By introducing early-age shrinkage and a suitable aggregate size, the modified compression field theory (MCFT) was found to accurately predict the shear strength of RHSC beams.