Simple homogenization model for the non-linear analysis of in-plane loaded masonry walls

A simple homogenized model for the non-linear and limit analysis of masonry walls in-plane loaded is presented. A rectangular running bond elementary cell (RVE) is discretized by means of a few plane-stress three noded triangular elements and interfaces. Non-linearity is concentrated on brick–brick interfaces and joints reduced to interface, exhibiting a frictional behavior with limited tensile and compressive strength with softening. Homogenized masonry behavior is then implemented at a structural level in a novel FE non-linear code relying on an assemblage of rigid infinitely resistant triangular elements and non-linear interfaces, exhibiting deterioration of the mechanical properties. Non-linear analyses are conducted on full scale walls – a deep beam and a windowed shear wall, for which experimental and numerical data are available in the literature – with a very limited computational effort. To circumvent some typical drawbacks of standard FE approaches, at each load step, all interfaces are assumed to behave as an elastic–perfectly plastic material and the discretized non-linear problem is solved by means of a standard sequential quadratic programming algorithm.