Resonances detected on a historical tower under bells’ forced vibrations

The aim of the paper is to perform a preliminary assessment of the dynamic behavior of the bell tower of Basilica Church “S.S. Medici”, one of the most important church in the town of Bitonto, Bari, Italy. The tower is 55 m tall and it is made in reinforced concrete. It is totally disconnected from the main structure of the Church. The structural behavior of the tower has been investigated by performing dynamic experimental tests, which have been executed in two different forcing conditions: recording the vibrations induced only by ambient loads, and, then the ones due to ambient loads and to the excitation produced by the bells. Four bells are housed in the lower bell chamber on a concrete bell frame, four more bells are housed at a higher level bell frame. All the bells are directly connected to the tower and swing in the same direction, so that their movement introduces a dynamic excitation on the tower. The experimental records have detected excessive movements on the tower when the bells swing.