Influence of shear reinforcement detailing on the shear capacity of reinforced concrete beams

Abstract Alternative shear reinforcement layouts that do not fully enclose the longitudinal tensile reinforcement can significantly improve the constructability of reinforced concrete (RC) members. However, their influence on shear transfer mechanisms is not yet fully understood. To address this gap, an experimental program comprising 10 shear tests on RC beams was carried out and complemented by a crack‐kinematics‐based evaluation of the individual shear transfer mechanisms. The results show that, for moderate shear reinforcement ratios, supplementary shear reinforcement significantly increases shear capacity. Specimens providing sufficient enclosure reach ultimate loads comparable to those of conventionally stirrup‐reinforced members, while the shear response is governed by pronounced crack localization. In this regime, dowel action of the longitudinal tensile reinforcement represents a major concrete‐related contribution to shear resistance and increases systematically with the degree of enclosure. Based on these findings, modifications to current shear design and assessment regulations are proposed by introducing a shear reinforcement factor accounting for the degree of enclosure. Within the investigated parameter range, the modified formulations provide significantly improved agreement between experimental and calculated shear capacities.