Monitoring the Modal Parameters of a Historical Belfry in Earthquake Prone Region

Masonry bell towers are significant expressions of past construction techniques and distinctive landmarks in historical centers of towns of the Inner Areas of the Apennines. Their preservation in earthquake prone regions represents a significant technical challenge, which can take advantage of advanced tools for structural assessment and monitoring under operational conditions as well as extreme loads. In this perspective, vibration-based Structural Health Monitoring (SHM) represents an attractive solution thanks to its minimal invasiveness and the ability to detect damage onset from the analysis of the global response of the structure without any prior information about the damage itself. The present paper illustrates preliminary results of modal-based SHM of the Civitacampomarano belfry. The tower is located close to a landslide and in an earthquake prone region, so timely assessment of possible damage plays a critical role for its conservation and maintenance. The architecture of the SHM system and the technological solutions adopted for continuous monitoring of the vibration response of the tower under operational conditions are described, focusing the attention on the effect of environmental variables and earthquake input on the modal parameters of the structure.