Influence of Longitudinal Reinforcement on One-Way Shear in Slabs and Wide Beams

Sectional shear models for slender reinforced concrete members developed by several research groups differ in the treatment of longitudinal reinforcement details when evaluating one-way shear capacity. Some models relate the shear capacity directly to the geometric reinforcement ratio while others consider the influence of reinforcement strain or stress. Further, only some models also consider the influence of member depth. The results from six new experimental tests on slender shear-critical members of varying depth, reinforcement ratio, and reinforcement strain at the time of failure are presented and compared with published data. The one-way shear stress at failure was accurately predicted using a recent modified compression field theory based capacity model that incorporates a “size effect” factor related to the member depth, and a “strain effect” factor related to the longitudinal reinforcement demands. Design implications for shear associated with the flexural reinforcement design strength are identified.