Rigid block and finite element analysis of settlement-induced failure mechanisms in historic masonry walls

The paper is related to the assessment of failure mechanisms of historic masonry structures suffering settlements induced by ground movements. Two numerical strategies are adopted in order to study the influence of the masonry shape and the settled zone on the cracking of masonry buildings: a discrete rigid block model and a continuous homogenized model. The first approach provides an estimate of the failure pattern of masonry based on the lower bound theorem of limit analysis. The second approach is formulated in the framework of multi-surface plasticity and is implemented in a finite element code for path-following non-linear analysis of masonry walls, described as continuous anisotropic plates. Several configurations of masonry walls under vertical settlement are investigated and the corresponding failure patterns resulting in local or global failure modes are presented. The results of the two models are compared and discussed in order to highlight pros and cons of discrete and continuous formulations in the prediction of settlement-induced damage of masonry structures.