Dynamic Behaviour of the Carillon Tower in Castel San Pietro Terme, Italy

This paper presents the experimental investigations conducted on the carillon tower of the Santissimo Crocifisso Sanctuary in Castel San Pietro (Bologna, Italy) and the analysis of data collected by using velocimeters and accelerometers installed on the structure. The main goal is to assess the effects of the swinging bells on the dynamic behaviour of the tower. The paper's novelty relies on the kind of structure monitored and the originality of the experiments. The structure is a rare example of a carillon tower, with fifty-five bells of different sizes, subjected to a careful measurement campaign never carried out before. Six experiments were conducted selectively by activating the bells to measure the tower's response induced by different vibration sources and determine the peak velocities recorded by using instruments at different heights. Two ambient vibration tests complemented the six experiments. The carillon's action induces low velocities on the tower, while experiments involving the bells swinging in the upper chamber produce the highest velocity values in the swinging direction; these values are more significant than those induced by the carillon alone. The most robust action is induced on the tower when all the bells (carillon plus swinging bells) ring. The experimental results are complemented by numerical simulations of the dynamic behaviour of the tower subjected to the action of a swinging bell.