Modelling of vaults as equivalent diaphragms in 3D seismic analysis of masonry buildings

Although it represents a crucial feature to be considered, the floor behaviour in 3D modelling is frequently assumed (with a rough approximation) as rigid. This hypothesis may be not completely acceptable in case of existing buildings (e.g. historical masonry structures), where various ancient constructive technologies can be found (i.e. timber floors or structural brick or stone vaults).