Effect of Load Distribution and Variable Depth on Shear Resistance of Slender Beams without Stirrups

The work and findings reported in the paper are interesting to the discussers and will advance the understanding of the shear-failure mechanism of reinforced concrete (RC) beams. Some details need further discussion and clarification. In many cases, shear is the governing failure mode in the RC beams without stirrups. The shear behavior of simply supported beams under a uniformly distributed load has been investigated in earlier studies to be essentially the same as the behavior under a point-loading arrangement of two-point loads at quarter points. Thus, the shear span of a beam with a uniform load has been defined as a = l/4, where l is the span length of the beam. For slender RC beams under a uniform load, an ideal shear span ai must be determined by analogy to point-loaded beams. When a beam is simply supported, the ideal shear span ai is the distance from the support to the tip of the critical diagonal crack.19 At ultimate shear failure state, the development of cracks through the inclined compression strut of a beam and its influence on the member’s shear strength shows a strong dependency on the shear span-depth ratio.8 Generally, the shear resistance of an RC beam will decrease with the increase of the shear span-depth ratio.