A FULL DISCRETE APPROACH FOR MODELLING THE ORTHOTROPIC SHEAR DAMAGE RESPONSE OF MASONRY WALL

The research deals with the modelling of the damage evolution and failure of masonry walls subjected to in-plane loading. The survey of damages suffered by some specific structural typologies, like the ancient masonry towers, shows the presence of vertical cracks that can be often related to a macroscopic mode II shear fracture. The classic orthotropy of a Cauchy continuum seems not able to fully describe this behaviour. The paper illustrates the application of an in-plane rigid body and spring approach (RBSM) that accounts for a more sofisticated shear orthotropy. Thank to the fact that this model has an intrisic capability to behave similar to a Cosserat solid material, at the macroscale, the proposed heuristic approach allows one to assign a different shear strength and internal friction parallel and normal to the bed joints. The numerical analyses show the capability of the proposed model to predict the crack pattern of an idealized masonry tower that can be qualitatively compared to the surveys of some well known examples of real towers subjected to seismic damages