Ambient Vibration Test of the Monastery of Salzedas and Optimisation of the Sensor Placement

This study focuses on the ambient vibration tests carried out at the Monastery of Santa Maria de Salzedas, a heritage building located in the north of Portugal. The fieldwork particularly focused on the south wing of the main cloister, which required urgent remedial measures in the past. The operational modal analysis allowed to identify five modes, three global, mainly horizontal, and two local, vertical, of the accessible roof. Several challenges arose, complicating the interpretation of the data, mainly due to low ambient-induced vibrations and intrusive activities. A Data-driven Optimal Sensor Placement (OSP) approach was explored as a strategy to determine the best sensor locations for collecting high-quality information while minimising the number of measurement points. To this end, the effective independence heuristic method was tested demonstrating that although the selected points ensure a good quality of the signal, their spatial distribution might hinder a correct interpretation of the mode shapes.