Structural modelling of complex historic masonry buildings

The simulation of the global behaviour of historic buildings, from a mechanical point of view, addresses the study of highly redundant structural systems. This includes complex geometry of structural elements (buttress, pier, walls, arch, vault, flying buttress, etc.), their connections, mechanical properties resulting from the varying texture of the masonry and further complicated by anisotropy due to the present damage from ageing and other factors. Structural modelling must take into consideration this evidence, also called experimental observation. The structural system is considered as an assembly of the elements. A systematic procedure is proposed to collect and use the experimental observations during the development of the FE model, at the element level. The importance of modelling details is related to the location of observed damage. Suppressing these features, the prediction of damage observations is not possible. Modifications of the model at the structural elements level and investigation in situ are adopted in an iterative way until the experimental observations are interpreted. The procedure is applied to the cathedral of Milan, example of elevated complexity. The numerical model developed provided interpretation of the load transfer mechanism for different structural configurations (following the construction history) and relative experimental observations (damage, deformations).