A macro-element approach for the seismic analysis of monumental buildings

The structural assessment under earthquake of ancient masonry churches remains a challenging task due to their intrinsic characteristics, i.e. the complexity of their geometry, the strong non-linear behaviour of the masonry material, the high computational burden related to the three-dimensional models adopted for the analyses, etc. The Italian Standard suggests to study the seismic behaviour of such a type of structures analysing separately the global response to seismic loads and the local behavior of a-priori defined portion of the building involved into collapse mechanism. In this work, the authors try to establish a link between the global behavior of the church and the assessment of the local mechanism by performing a two steps procedure based on: i) the detection of the main vibration modes of the whole building with the identification of the structural macro-elements responsible for the overall seismic vulnerability and ii) the definition of the failure patterns due to earthquake by carrying out a series of finite element non-linear static analyses on the previously-identified macro-elements.