A shear stress-slip relationship in steel fibre-reinforced concrete obtained from push-off testing

This paper presents the results of an experimental programme carried out to evaluate the shear stress slip relationship in steel fibre-reinforced concrete. Two types of direct shear tests are modified and used. Firstly, a general, double-notched, direct shear test was modified to minimise the confinement stress provided by the restricted supports in the general test setup. Secondly, a traditional Z-type push-off test, with reinforcement crossing the pre-cracked shear plane, was used to determine the shear crack propagation in steel fibre-reinforced concrete. Two aggregates with different maximum particle sizes and two volume fractions of steel fibres were used. The modified, double-notched, direct shear test reduces the influence of the horizontal restraint forces on the supports and provides more accurate shear strength values for non-cracked shear planes. The results of push-out tests in specimens with pre-cracked shear planes, show that steel fibres contribute to reducing the crack width of the shear plane in the pre peak shear stress branch. A model for predicting the shear stress-slip is proposed and is based on three components: shear strength of cracked concrete, shear-friction and contribution of steel fibres crossing the cracked plane. A good correlation was obtained for the experimental results and the values predicted by this model. (C)& nbsp;2021 Elsevier Ltd. All rights reserved.