Modelling mixed mode fracture of mortar joints in masonry buildings

Within the framework of Discrete Element Modelling of masonry structures, a contact law based on Cohesive Zone Model and Coulomb's law is proposed to describe the fracture behaviour of mortar joints. The contact law is expressed in mixed mode I + II and is based on the cohesive behaviours of pure modes I and II and on the frictional behaviour whose parameters can be estimated from an experimental procedure consisting in two fracture tests. Moreover, it is shown from numerical simulations that the contact law exhibits a load path dependency in agreement with the quasi-brittle behaviour expected for mortar. Finally, a parametric study performed from the simulation of the diagonal compression of a masonry panel shows a good agreement of the obtained load-displacement responses and failure modes compared to experimental results of the literature