Effect of artificially bond-degraded longitudinal tensile reinforcements on shear behavior of simply supported RC beams without stirrups

To investigate the effect of bond degradation between longitudinal tensile reinforcements and concrete on the shear behavior of simply supported RC beams without stirrups, nine specimens were tested in this study. The test parameters included shear span-depth ratio and bond-degraded length of longitudinal tensile reinforcements, with the bond degradation created by a mechanical-based artificial technique. ATENA software was employed for finite element analyses, incorporating bond-degraded patterns, longitudinal tensile reinforcement ratio, and shear span-depth ratio as analysis parameters. The results indicated that the maximum loads of all beams exhibited an overall upward trend, with the number of cracks decreasing as the bond-degraded length increased. When the longitudinal tensile reinforcement ratio was 1.58%, the beams with shear span-depth ratios of 1.5, 2.0, and 2.5 exhibited a transition in failure modes from shear-compression to flexural-shear or flexural failure as the bond-degraded length increased, irrespective of the specific bond-degraded patterns in longitudinal tensile reinforcements. In contrast, the beams with a shear span-depth ratio of 3.0 exhibited diagonal tension failure, shear-compression failure, flexural-shear failure, and flexural failure. When the longitudinal tensile reinforcement ratio reached 2.05%, the longitudinal tensile reinforcements in all beams did not yield at failure.