Un modello non lineare per la muratura a più paramenti

A numerical nonlinear model was developed to analyze the mechanical behaviour of multi-leaf masonry, a type of building technique frequently encountered in ancient structures. A damage model, previously developed by some of the authors, was adapted to fit stress-strain curves obtained though tests performed on the single layers of multi-leaf panels, either made of stones with mortar joints, or mortar and aggregate. In this model, damage is characterized by a second-order, symmetric tensor, whose eigenvectors are associated with the crack orientation and remain fixed once any crack is activated, whatever the subsequent load history be. The modified model was implemented into a nonlinear finite element code. Its reliability was assessed through comparisons with results of tests performed on three-leaf masonry panels. Most of the numerical analyses predict the experimentally measured peak load with good accuracy. Usually, the post-peak behaviour is not satisfactorily described: this is likely to be attributed to numerical instabilities, which will be overcome in future developments.