Historic multi-leaf masonry walls: experimental and numerical research

Following several failures of historic buildings occurred in the recent past, a research programme was carried out with the aim of investigating the mechanical behaviour of multiple-leaf stone masonry walls. A number of experimental tests were performed on three-layered specimens, consisting of two external leaves made of regularly cut stones and mortar joints, and an internal leaf simulating a rubble filling. The tests differed in terms of interface geometry and stone nature of the specimens, and in terms of loading conditions. A numerical model was developed to predict the nonlinear response of the specimens. The model is characterized by a damage tensor, which allows for the description of the damage-induced anisotropy accompanying the cracking process. Comparisons between the predicted and measured failure loads and average stiffness of the specimens are quite satisfactory in most of the studied cases. The numerical procedure still needs to be improved to accurately describe the post-peak behaviour, by avoiding mesh-dependency effects related with the strain-softening behaviour of the material.