Content-based composites are traditionally a commonly used material in civil engineering structures. The basic representative of this type of material is concrete, a quasi-brittle composite in which crack resistance can be achieved by the addition of fibres. The double-K fracture model can be used to calculate the fracture-mechanical parameter values of structural concrete with and without popypropylene fibres. This model combines the concept of cohesive forces acting on the crack length with a criterion based on the stress intensity factor, using a ‘softening function‘ to determine the cohesive part of fracture toughness. In this paper, authors determine the effect of the type of this softening function on the evaluation of fracture tests performed on sets of concrete specimens with and without polypropylene fibres. and Obsahuje seznam literatury
The present paper describes a semi-analytical fracture model based on the cracked hinge approach by Ulfkjær [1]. Some extensions of the original fomrulation are introduced and also implemented (as JAVA code) to enable the use of any softening function with arbitrary shape for the cracked part of the model, which is considered as a fictitious (cohesive) crack. The application of the model to the wedge-splitting test (WST) is validated, showing the consistency of the adopted formulations with reference data. Furthermore, the capability of the model to integrate various softening curves is verified using FEM simulations. and Obsahuje seznam literatury