In quasi-brittle materials, such as reinforced concrete, localisation of initially diffuse cracking evolving in localised cracking patterns consists of a numerically challenging task. With conventional iterative methods, convergence of the numerical solution scheme to model crack localisation is often difficult to obtain. On the other hand, conventional total approaches, such as the Sequentially Linear Approach, although robust, fail to approximate properly the underlying material law. In the present work, a new model is introduced, designated the Total Iterative Approach, in which the internal damage variables are updated iteratively. It is found that this approach is robust, allows for the correct approximation of the material law and is a powerful tool for the analysis of softening behaviour. Some examples are presented to illustrate the performance of the model.

Corrosion in reinforced concrete is an important feature which can lead to increased deformation and cracking, as well as to premature failure. In the present work, macro-mechanical modelling of corrosion is performed, namely the degradation of bond–slip between concrete and steel. A mixed-mode damage model is adopted, in which the interaction between the bond–slip law and the stress acting in the neighbourhood of the concrete–steel bar interface is taken into account. Bond–slip degradation is modelled using an evolutionary bond–slip relationship, which depends on the level of corrosion. Different relevant loading cases are studied. Special attention is given to the evolution of corrosion in time, under constant load. This is done by adopting a Total Iterative Approach, in which the structure is reevaluated each time step, upon damage increase due to corrosion. Pullout tests are presented to illustrate the performance of the model. Bending tests are also performed to evaluate the influence of corrosion at structural level.

In this manuscript mixed-mode fracture in quasi-brittle materials is studied. A damage model is first introduced in the framework of the discrete crack approach, in which the limit surface is defined in the traction space. Dilatancy is included in this model as an additional compliance. Some experimental results are simulated, which give rise to further refinement of the model due to the effect of dilatancy. One new model is introduced, based on a nonlinear fracture mechanics approach. This is a purely incremental hypoelastic model, which cannot be derived in the framework of the damage mechanics theory. The numerical results of the two models are compared. In particular, it is found that the fracture mechanics model can better meet the requirements needed for the simulation of the experimental results.