The seismic assessment of historical masonry structures

structures constitutes a contemporary issue in most seismic regions around the world and particularly in Europe where monumental buildings represent a significant cultural heritage which must be preserved. In most cases seismic retrofitting projects of monumental structures have been performed without first proceeding to a reliable assessment of the actual structural conditions. This apparent paradox is mainly due to difficulties related to the numerical prediction of the seismic behaviour of monumental structures. Refined finite element numerical models, such as the smeared cracked and discrete crack finite element models, able to predict the complex non-linear dynamic mechanical behaviour and the degradation of the masonry media, need sophisticated constitutive laws and significant computational cost. As a consequence, these methods are nowadays unsuitable for practical application and extremely difficult to apply to large structures. Many authors developed simplified or alternative methodologies that, with a reduced computational effort, should be able to provide numerical results that can be considered sufficiently accurate for engineering practice purposes. However, most of these methods are based on too simplified hypotheses that make these approaches inappropriate for monumental buildings. In this paper a new discrete-modelling approach, conceived for the seismic assessment of a monumental structure, is applied to a benchmark historical basilica church for which results are available in the literature. The proposed numerical strategy represents the first introduction of the discrete-element approach able to represent masonry structures with curved geometry and, at the same time, to simulate both the in-plane and the out of plane response of masonry media.