NUMERICAL CALIBRATION OF A MACRO-ELEMENT FOR VAULTED SYSTEMS IN HISTORIC CHURCHES

The present paper proposes to represent vaults in an extremely simplified manner, by means of equivalent trusses. In the context of seismic vulnerability of historic churches, numerical tools are required in order to easily interpret their overall dynamic behavior. In addition to kinematic analyses, global analyses may be useful to identify vulnerable macro-elements in churches characterized by the presenceof vaulted systems. Vaults often play an important role by connecting colonnades and external walls in basilica-type churches. Since techniques for modeling such structural elements are generally time-consuming and it is often useful to have simple tools to take them into account, they are regarded as macro-elements by adopting the usual approach accepted for churches and masonry structures. Trusses stiffness in different directions is obtained with both linear and non-linear static analyses. Finite element models are analyzed to perform parametric analyses for different vaults typologies and values of vaults plan dimensions or ratio rise-to-width. The equivalence is validated by means of comparisons between the actual model, where vaults are fully modeled, and the simplified one, with equivalent trusses. An example is provided to show the capability of the proposed technique. A sensitivity analysis is also carried out in order to evaluate differences in the dynamic behavior of the whole church replacing vaults with horizontal slabs of different thickness. Finally, time-histories analyses monitoring relative displacements are performed to observe differences in the response of the simplified and the actual model.