The seismic vulnerability assessment of a stone masonry building enclosed in aggregate

When assessing the seismic vulnerability of old buildings within historical centres, it is very difficult to individuate a determined building as an independent structure as they often share the same boundary walls. Indeed, over the centuries, the diachronic process of building up, in adjacency and in continuity with the existing built environment, has led to the complete saturation and occupation of free spaces and to the creation of complex structural systems, in which structures may differ in geometry, materials, construction techniques and state of preservation. It is known that buildings in aggregate do not have an independent structural behaviour given the reciprocal interactions with adjacent structures. However, and even though several attempts have been made in recent years to address this issue, it is not yet clear how these interactions can be accounted for in numerical models even if in a simplified form, without the need for modelling the entire aggregate. Hence, this paper aims at understanding how the “aggregate effect” should be modelled for a more accurate assessment of the seismic performance of existing masonry buildings located within historical centres. To this end, different modelling configurations of a case study building located in the “Bairro Ribeirinho” neighbourhood in Faro (Portugal) were considered by using a software code based on the macro-elements approach. The results are presented and discussed in terms of in-plane seismic capacity, after performing non-linear static analyses. Furthermore, the paper discusses the usefulness of global pushover analyses for the seismic assessment of buildings enclosed in aggregate.