Modelling fracture on polyolefin fibre reinforced concrete specimens subjected to mixed-mode loading

In recent years, polyolefin fibres have proved a remarkable performance as reinforcement of concrete, which has inspired a number of studies involving, among others, the simulation of fracture on polyolefin fibre reinforced concrete (PFRC) specimens. Fracture has been successfully reproduced on PFRC specimens in the past by means of an embedded crack model with a trilinear softening function, but always using for comparison the classical three-point bending test, which employs a symmetrical setup and induces fracture under pure mode I conditions. In the present study, six sets of specimens tested under an alternative setup of the three-point bending test, which induces fracture under mixed-mode conditions (I and II), are simulated using the same numerical approach. The results not only prove that the use of a trilinear softening function together with an embedded cohesive crack approach can reproduce fracture under mixed-mode conditions, but also provide interesting insights on how the trilinear softening function may be designed for suiting the usage of different fibre lengths or varying the proportions of polyolefin fibres.