Seismic in-plane displacement capacity of masonry barrel vaults: the role of constructive aspects

Historic masonry vaults are one of the most vulnerable elements with respect to the seismic action. Cracks are often detected after post-earthquake surveys. However, it is difficult to directly link the observed damage to causes. Different mechanisms can occur during an earthquake, such as in-plane horizontal shear distortion or longitudinal opening/closing of the abutments. These mechanisms are not necessarily associated to a specific crack pattern, since other factors are involved in the determination of the detected crack status. Among these factors, constructive aspects (such as the brick pattern) play a major role. This study aims at investigating the possible correlation between constructive aspects and the crack pattern in barrel vaults subjected to in-plane shear mechanism. Numerical simulations are carried out on an ideal circular vault with a rectangular base of dimensions 3.1x5.3 m, and rise of 1.175 m. Three brick patterns are considered: radial, diagonal and vertical. In order to investigate these aspects, a micromodelling numerical approach has been adopted. Results are presented in terms of ultimate displacement capacity, collapse mechanisms and crack pattern charts.