Novel Calculation Method for the Shear Capacity of a UHPC Beam with and Without Web Reinforcement

To accurately predict the shear-bearing capacity of UHPC beams, it is crucial to quantify the shear contribution of the fiber bridging effect and UHPC compression zone. Nevertheless, it should be noted that the shear contribution of UHPC in the compression zone is not fully considered in most existing calculation methods, and the probability distribution of fibers within the matrix is also not taken into full account, which reduces the calculation accuracy of the shear bearing capacity of UHPC beams. In this paper, a UHPC beam shear test database containing 247 samples was created, and the influencing factors on the shear capacity of UHPC beams, such as the shear span ratio, the web reinforcement ratio, and the volume fraction of steel fiber, were analyzed. It was found that the ratio of cracking load to ultimate load ranges from 0.2 to 0.6, and the failure in the compression zone of UHPC beams can be divided into diagonal tension failure and shear compression failure. Based on the failure mechanism of the compression zone, considering the contribution of fiber micro tensile strength, a formula for calculating the shear-bearing capacity of UHPC beams with and without web reinforcement was proposed. Verified by experimental data, the proposed formula accurately predicts the shear-bearing capacity of UHPC beams. In comparison with other shear capacity formulas in current design codes, the proposed formula in this paper provides a higher prediction accuracy.