Seismic Response of Masonry Building Aggregates in Historic Centres: Observations, Analyses and Tests

Abstract

The high seismic vulnerability of historical centres, mainly constituted by masonry building aggregates, has been highlighted both in post-earthquake surveys and from numerical analyses and experimental tests. Their seismic behaviour is affected by structural irregularity and by the interactions between adjacent buildings, typically scarcely connected. The assessment of the response of these building conglomerations is complex, due to the difficulty of modelling the entire aggregate, both for computational issues and for the need of gathering information on units that are not the object of study. On the other hand, isolating and modelling the structural unit of interest is in most cases not meaningful, due to interactions with adjacent buildings, which can be hardly reproduced by introducing appropriate constraints and tributary masses. These issues are explored in this paper, referring to in-situ observations, numerical analyses and results from experimental shake-table tests on masonry aggregates. The results highlight that building position within the aggregate can be a governing parameter only in case of regular and homogeneous aggregates, whereas in the usual case of aggregates with structural units of different height and characteristics, the response is governed by the interactions between adjacent units, with damage concentration at the interface.