Shear Behavior and Diagonal Crack Width for Reinforced Concrete Beams with High-Strength Shear Reinforcement

ACI 318-11 specifies that the yield strength of shear reinforcement be limited to 420 MPa (60,000 psi) in a shear design equation. However, this is not the case in other design codes, such as EC2-04, CSA-04, and JSCE-02, where a yield strength of shear reinforcement of more than 420 MPa (60,000 psi) is allowed in shear design. The primary reason for the limit of 420 MPa (60,000 psi) in ACI 318-11 is to provide enough transverse reinforcement and, hence, control diagonal crack width. To investigate this, a total of 18 reinforced concrete (RC) beam specimens incorporating high-strength shear reinforcement were tested and the applicability of the reinforcement was then assessed In addition, the diagonal crack widths from the current test results and the 38 RC beam experimental results available in the technical literature have been evaluated by comparison with the crack regulation of ACI 318-11. Comparative results reveal that diagonal crack width can be influenced by the amount of shear reinforcement and compressive concrete strength. In short, the width is inversely proportional to amount of shear reinforcement divided by compressive concrete strength.