Monitoring of environmental and sound-induced vibrations on artistic stained glasses

Stained glasses are a key component of the artistic heritage of most European Christian cathedrals. During the last thousand years they grew in complexity and extension until they reached the size of several square meters. Therefore, artistic stained glasses are one of the elements of cultural heritage that are most exposed to environmental hazard though seldom considered until recent days. One of the modern danger sources for stained glasses are environmental vibrations and sound pressure induced vibrations. Considering the lack of modern literature on this topic, the authors carried out an experimental investigation on the Duomo di Milano stained glasses vibrations. The experimental campaign focused on the dynamic response of glasses due to both environmental vibration and to sound-induced excitation during some events which took place in the big square facing the church. As a result, a preliminary vibration analysis has been computed, thus enabling the characterization of vibrations and their effects under operating conditions. Data show that the response for this type of glass under operating conditions is limited to the 30–200 Hz band, with a concentration of energy in the 40–80 Hz band. Furthermore, considering a 30–200 Hz band, the RMS vibration level due to pop/rock concerts is about 10 times higher than that due to environmental excitation.