Modelling in-plane micro-structure of masonry walls by rigid elements

This paper proposes rigid elements for a specific simplified model of the in-plane behaviour of masonry walls made of regular textures. The elements are plane, quadrilateral and connected by two normal springs and one shear spring on each side. The mechanical characteristics of these connections are defined in consideration of the texture effects arising due to the mechanical degradation of mortar. The present approach has proved effective when transferring the essential texture information from micro-scale to macro-scale. In particular, the ``local rotation'' of the blocks is obtained by assigning different stiffness to the shear springs, according to their orientation, while the in-plane bending stiffness can be reproduced by properly disposing the two normal springs. Depending on the geometry of the textures, these aspects are significant in case of large differences in the elastic modulus of the constituents, as is the case of masonry walls subjected to heavy seismic loading. Numerical simulations have proved that it is possible to deal with these aspects with a very reduced computational effort which is promising for non-linear dynamical analyses applications.