Seismic Behaviour of Multi-Arched and Multi-Vaulted Historical Masonry Structures

Ancient masonry structures are often made of arches, vaults and domes. Many of such structures stand in earthquake-prone countries of the Mediterranean area (like Italy, Spain and Lebanon). During their long life they have experienced different levels of seismic actions, suffering from minor damages to partial or total collapse. Although being robust and stable under vertical loads, unreinforced masonry constructions are typically vulnerable to horizontal actions which may induce out-of-plane mechanisms and the development of plastic hinges in arches and vaults. To preserve the vast Mediterranean historical built heritage, an in-depth comprehension of the seismic behaviour of arched and vaulted masonry constructions is thus essential. With the aim of contributing to this matter, the paper referred to three noteworthy case studies: a middle-age Italian tower, an eighteenth-century multi-arched Spanish aqueduct and an eighteenth-century multi-vaulted Lebanese hammam. Three-dimensional models of the real structures, identified via experimental modal tests, were considered. The anisotropic and non-linear behaviour of masonry was accounted for by means of an elastic–plastic damage constitutive law. Dynamic non-linear analyses were carried out under spectrum-consistent earthquakes to predict the damage pattern of the three different structures. Two kinds of earthquakes (pulse-like and multi-peak) were considered, and different ratios between tensile and compression strength were considered. The comparison of the results gives some insights on the post-elastic seismic demand on masonry buildings with linear or curved shapes under different kinds of earthquakes and for lowering values of the strength ratio.