Post-diction analysis of an unreinforced masonry building aggregate using the Discrete Macro-Element Method

Unreinforced masonry (URM) aggregate buildings constitute a significant portion of the European built heritage and are widely distributed in historic urban centres. Their seismic assessment remains particularly challenging due to geometric irregularities, material heterogeneity, and the complex interaction mechanisms between adjacent structural units. In this context, the SERA-AIMS experimental campaign provides a valuable benchmark for the validation of numerical modelling strategies through shaking table tests on a half-scale masonry aggregate. This study presents a post-diction analysis of the SERA-AIMS specimen using a three-dimensional Discrete Macro-Element Method (DMEM) model implemented in the HiStrA software. The numerical model is calibrated on the basis of available experimental data and further refined through sensitivity analyses aimed at assessing the influence of the most relevant mechanical parameters on the structural response. Nonlinear analyses, including Incremental Dynamic Analysis (IDA) and pushover analysis, are performed to investigate the seismic behaviour of the prototype. The results show that the proposed model is able to reproduce the global response of the specimen with satisfactory accuracy, particularly in terms of base shear and failure mechanisms, while maintaining limited computational demand. However, the model tends to underestimate displacement demand at high seismic intensity levels. Overall, the study confirms the potential of the DMEM approach as an efficient numerical tool for the seismic assessment of masonry aggregates, while also highlighting the need for further developments to improve the prediction of displacement capacity and damage evolution.