Creep failure of ancient masonry: experimental investigation and numerical modeling

The recent collapse of some ancient massive buildings has raised attention on the creep behaviour of masonry. An extensive experimental and theoretical research program is being carried out on this topic at the Politecnico of Milan. The results are presented of accelerated creep tests to failure on brick masonry samples taken from a building (the Cathedral of Monza, Italy) that shows signs of serious damage. Then, a recently developed theoretical model is proposed to simulate the experimental results. It is based on the theory of viscoelasticity coupled with two anisotropic damage variables, allowing, respectively, for damage induced by monotonically increasing stresses and by sustained stresses. The numerical simulations performed so far are quite encouraging, so that the applicability of the proposed model to structural analyses can be envisaged.