Effect of degradation of constituents on global performance of historical masonry

Conservation and valorisation of World Heritage often overlap with assessment and analysis of masonry historical constructions. Masonry is characterized by the large variability of its components. Parameters like strength, bond, workmanship defects in construction and material decay strongly influence the performance of the overall structures. Even equal unreinforced walls tested in laboratory show very different behaviours and the test results can be very scattered. The large scatter experimentally observed can be explained not only by considering the scatter of basic material properties, but also the effect of defects, which are more significant in the case of a natural stone. Numerical analysis provides some useful insights on the simulated experimental tests on tuff masonry. The results of the preliminary FEM analyses provided satisfactory results. Natural stone imperfections and defects were simulated in the models. The effect of joints not fully and not uniformly filled were considered, influencing global capacity and cracking: two types of crack patterns were observed involving only the mortar joints or both mortar and tuff bricks. Degradation impacts differently mortar and bricks. Such variability has been simulated by means of validated FEM models to evaluate global decay of masonry capacity depending on expected decay of the components of masonry, namely mortar and bricks.