An Equivalent Frame Digital Twin for the Seismic Monitoring of Historic Structures: A Case Study on the Consoli Palace in Gubbio, Italy

Recent advances in computing performance and simulation tools allow today the development of high-fidelity computational models which accurately reproduce the structural behavor of existing structures. At the same time, advancements in sensing technology and data management enable engineers to remotely observe monitored structures in a continuous and comprehensive way. Merging the two approaches is a challenge recently addressed by the engineering research community, which led to the concept of digital twin (DT)—a simulation model continuously fed by sensor data which, throughout the whole lifespan of the structure, stands as its digital proxy. In the seismic field achieving such a task is still problematic, in particular for large and complex structures such as historical masonry palaces. To this aim, the paper proposes the integrated use of DTs and vibration data to support the seismic structural health monitoring of monumental palaces, discussing a practical application to the historical Consoli Palace in Gubbio, Italy. To overcome the computational limitations of classical approaches, an efficient equivalent frame (EF) model of the palace is built and continuously updated in quasi real-time based on modal information identified from vibration data. The performance and accuracy of the Equivalent Frame model are compared with those of a high-fidelity Finite Element representation, highlighting both their feasibility and limitations. Employing modal data recorded across the 15 May 2021 earthquake, the EF model demonstrates the ability to quickly assess the structural integrity of the palace in the post-earthquake scenario, as well as to forecast the residual capacity with respect to future seismic events.