Comparative Study of Shear-Span-To-Depth and Reinforcement Ratio on High-Strength Concrete Beams

The shear strength of reinforced concrete members with or without shear reinforcement is influenced by the shear span to effective depth and longitudinal tensile reinforcement ratios. In high-strength concrete, if the paste has a higher strength than the aggregates, then propagation of cracks is possible through the aggregates rather than around the aggregates, and the concrete may fail with a brittle failure, which is against most of the guideline’s philosophies. This paper investigates experimentally the influence of the shear-span to effective depth ratio and the longitudinal tensile reinforcement ratios on the behavior of the shear strength of HSC beams having no shear reinforcement. A total of fifteen reinforced high-strength concrete beams with different longitudinal reinforcement ratios were fabricated and then tested under a two-point bending test with shear-span to effective depth ratios varying from 1 to 3. Experimental results were compared based on design codes and state-of-the-art models. The influence of shear-span to effective depth ratio and longitudinal tensile reinforcement ratio is unaccounted for in most design guidelines and prediction models; therefore, the predicted values are either underestimated (up to 50%) or overestimated, except for the Zsutty Model, which has accurately predicted the shear strength values for all shear-span to effective depth and longitudinal tensile reinforcement ratios. As in the future, high-strength concrete will be more likely used in RC construction, this study directs the understanding of model assumptions for shear prediction before its use.