Shear capacity of high-strength concrete beams with their point of inflection within the shear span

Abstract

The shear strength of concrete does not increase in proportion with the concrete grade. Thus, when high-strength concrete is used in place of normal-strength concrete, the shear capacity of the structure could become critical. In the study presented, the effect of concrete strength on the shear capacity of concrete beams was investigated. As previous research on normal-strength concrete beams has shown that the presence of an inflection point within the shear span can significantly influence the shear capacity, particular effort was made to study this influence in the case of high-strength concrete beams. The results indicate that, as the concrete strength increases, the shear capacity of the beam also increases, but the shear capacity is proportional to the cube-root rather than the square-root of the concrete compressive strength. It is also revealed that the presence of an inflection point can increase the shear capacity by as much as 100%, regardless of whether normal-strength or high-strength concrete is used. Finally, the test results were analysed by comparing them with the predicted strength values calculated using the formulae given in the various codes and Aoyagi's equation.