Why is Shear Strength of Concrete dependent on % of Longitudinal Reinforcement ?
- The increase in pt in the flexural tension zone contributes to enhanced dowel action Vd and control the propagation of flexural cracks.
- This results in increase in the position of the neutral axis as evidenced by the equation 𝑥𝑢/ 𝑑 = 0.87 𝑓𝑦 𝐴𝑠𝑡 / 0.36 𝑓𝑐𝑘 𝑏𝑑
- The increased area of uncracked concrete in compression zone enhances contributions of Va and Vc .
- Thus the higher the percentage tension reinforcement, the greater the shear resistance in the concrete – up to a limit :