Pre- and post-earthquake structural identification of a historical belfry

Operational Modal Analysis (OMA) techniques are able to provide relevant information about the global dynamic behavior of structures under operational conditions, supporting detection of potential damage without any prior knowledge about it. As a result, OMA is frequently applied in combination with model updating for the non-destructive assessment of heritage structures. The present study deals with OMA and Finite Element modelling of a historical belfry, which experienced a change in its fundamental dynamic properties after an earthquake. Starting from a comparison between the experimental results before and after the seismic loading, the paper describes the development of the numerical model of the bell tower and its refinement against experimental data from dynamic tests. By adjusting the numerical model to replicate the observed experimental behavior and comparing the changes in selected updating variables, opportunities and limitations of OMA-based structural identification for the non-destructive health assessment of heritage structures in earthquake prone regions are discussed, remarking their promising role for safeguarding of historic masonry structures.