Shear strength assessment of RC members: influence of shear reinforcement and yielding of the flexural reinforcement

Abstract

[EN] An extensive experimental programme consisting of 15 shear tests on continuous reinforced concrete beams was carried out to assess the shear strength of beams with and without shear reinforcement. The influence of large flexural strains in the shear strength was analysed as the tests were designed to fail in shear after yielding of the flexural reinforcement. The assessment of the shear strength was investigated based on the contribution of the various potential shear-transfer actions following the possibilities offered by Digital Image Correlation (DIC). In this field, several approaches accounting for the role of the various shear-transfer actions have recently been proposed, such as the Critical Shear Crack Theory or the Compression Chord Capacity Model, and significant advances on the analysis of the activation of these shear-transfer actions have been performed by the use of DIC. In this work, detailed surface displacement measurements were performed by means of DIC, allowing to track the development and kinematics of the critical shear crack leading to failure. Based on this information, together with suitable constitutive models, the amount of shear transferred by each shear-transfer action was estimated at different load levels and at failure. The calculated shear strength of the specimens was obtained as the sum of the contribution of the various shear-transfer actions at failure and its comparison with the experimental results showed consistent agreement for the different cases. Based on the results, different conclusions and implications about the contribution of the various shear-transfer actions at shear failure are presented. In general, the contribution of each shear-transfer action is strongly influenced by cracking patterns and by the location, shape and kinematics of the critical shear crack.