Luong test for the characterization of the shear post-cracking response of fiber reinforced concrete

The behavior of concrete subjected to shear can be significantly improved by the addition of fibers, which may partially or totally substitute the traditional steel stirrups (also known as links). Design recommendations include formulations to account for the contribution of the fibers. However, these formulations take the results of small-scale bending tests as input parameters. The main reason for that is the lack of standardized tests and the difficulty to assess direct shear in fiber reinforced concrete (FRC) both for the design and for the quality control. The present study proposes a test for the characterization of the post-cracking shear response of FRC. The test is validated through an experimental program with conventional concrete and FRC. The influence of different parameters (geometry of the specimen, the type and the content of fiber) is assessed and a comparison is made between the push-off test and the one proposed here. Results of an in-depth statistical analysis indicate that the latter is a simpler and valid alternative to evaluate the post-cracking shear response of FRC.