Vibration Monitoring and Seismic Response of the Milan Cathedral

Structural Health Monitoring (SHM) is a promising approach for assisting the condition-based structural maintenance of heritage buildings, via the continuous analysis of diagnostic data collected by a network of sensors. Within this context, vibration-based SHM is receiving increasing attention but the practical applications on heritage structures are still not frequent and generally based on the use of a limited number of sensors. The paper is mainly aimed at presenting selected results from the dynamic monitoring of the Milan Cathedral. It should be noticed that the dynamic response of the structure is continuously collected in a reasonably well distributed measurement grid (27 channels of data), so that mode shapes-based methods could be conveniently used for anomaly detection and localization. After a concise historic background on the historic monument and a description of the dynamic monitoring system installed in the Milan Cathedral, the paper focuses on the dynamic characteristics of the monument and on the monitoring of environmental parameters. Subsequently, the results collected in the first years of dynamic monitoring are presented and discussed, with special attention being given to the influence of environmental parameters on the variations observed in the modal behavior of the building. Furthermore, as the response to seismic events was recorded during the monitoring, comments are given on the seismic behavior of the cathedral.