Modelling and analysis of an ancient monastery under earthquake loading: assessment of seismic resistance

The paper discusses the static behaviour and the seismic vulnerability of a historical building, in particular a monastery currently used as a Regional Headquarter of the Marche Region by the Italian Army. The building is located in Ancona, a site characterized with a medium-high seismic risk. Monasteries, as churches, represent a large portion of the Italian (and European) cultural heritage particularly susceptible to damage and prone to partial or total collapse under earthquake loads; for these reasons they are of economic and engineering concern. The high seismic vulnerability of this type of buildings is due to both the specific mechanical properties of masonry materials (characterized by a very small tensile strength) and the particular configuration of the buildings itself, which are characterized by an open plan layout often with perimeter slender walls. Moreover the vulnerability of these historical masonry buildings is enhanced by the absence of adequate connections between the various parts constituting the structural complex and by the presence of thrusting horizontal structures (triumphal arches, etc.) as already discussed in several studies [1,2]. Furthermore, it is no longer used as a monastery, a fact that changes the hazard aspects [3]. A finite element methodology for the static and dynamic analysis of historical masonry structures is described and applied to the case study. In particular 3D linear and nonlinear analyses (which take into account the nonlinear behaviour of masonry) are performed. Also constitutive assumptions, characterized by elasticity, damage and friction, are done. The behaviour of the masonry is simulated by use of solid elements which can have their stiffness modified by the development of cracking and crushing. The comparison demand vs. capacity confirms the susceptibility of this type of buildings to extensive damage and possibly to collapse. At the end, we have conducted some analyses of active failure mechanisms in the light of the observed state of damage and of the FEM results.