Effect of stirrups on shear performance of geometrically-similar reinforced concrete deep beams: An experimental study

Abstract

In practical engineering, reinforced concrete (RC) beams with stirrups are the predominant form of RC beams. The geometric dimensions of RC beams are large, and the brittle shear failure of them maybe show the characteristics of size effect. However, current research primarily focuses on the size effect of shear failure in RC beams without stirrups, with less emphasis placed on those with stirrups. Furthermore, when the minimum stirrup ratio is exceeded, there is no consensus regarding on whether the size effect still exists. Therefore, the objective of the present work is to discover the influence of the stirrup ratio on the size effect in RC deep beams. In this work, the shear failure experiment of RC deep beams considering the structural size (maximum beam height of 900 mm) and stirrup ratio (0%∼0.942%) is designed and completed. The experiment results indicate that: 1) for the beams without stirrups, clearly, the corresponding size effect on the shear strength is the most obvious, with beam depth increases from 300 mm to 900 mm, the nominal shear strength decreases approximately by 41%; 2) as the stirrup ratio increases from 0 to 0.942%, the size effect is weakened with the presence of stirrups; 3) however, size effect cannot be completely eliminated even when the stirrup ratio reaches as high as 0.942%; (4) generally, for the stirrup ratio of 0.3%, there is a decrease in nominal shear strength by 20%, indicating that consideration of size effects should be taken seriously in practical concrete structure design; (5) moreover, Jin et al.’s size effect law is also compared and validated by the present test data.