New Experiments on Shear Properties of Fibre-concrete

Concrete reinforced by dispersed fibres (or simply fibre-concrete) is relatively new material. The motivation for adding fibres into concrete is to reduce natural brittle character of concrete. The biggest benefit of dispersed reinforcement is in its positive influence on fracture energy and ductility. The behaviour of fibre-concrete exposed to bending moment (or combination of bending moment and shear force) was investigated many times and it is well understood. Nevertheless, none of realized experiments investigated the performance of fibre-concrete in pure shear mode. In this context, it should be noted that in many real applications fibre-concrete is affected by significant shear forces. In order to remedy this situation, the new arrangement of experiment was proposed: large-scale tubes to which pure torsion is applied. In thin walls of designed simply supported tubes the pure shear is produced by application of torque. During experiments, not only ultimate shear strength was measured, but also the descending post-peak curve of transmitted stress was observed. These results enable to derive the stress–strain relation in the whole range of stress-strain diagram in the pure shear mode.