Experimental and Numerical Studies on the Bell Tower of the Transfiguration Basilica on Mount Tabor, Israel

The Church of the Transfiguration is a Catholic Basilica located on top of Mount Tabor in Galilee, Israel. It was built in 1924 following the design of the Italian architect Antonio Barluzzi on the ruins of an ancient Byzantine church (4th-6th century) and of a Crusader church (12th century). The façade of the church is characterised by two twin towers, connected by an arch supported by two columns. Bells are located only inside the South Tower. An extended crack pattern affected the Bell Tower, caused by the dynamic actions of the bells, transferred through the existing steel bellframe rigidly connected to stone masonry walls. A Finite Element Model of the Bell Tower has been implemented in order to evaluate its structural behaviour and dynamic response to static and dynamic loading. The model has been calibrated using a dynamic identification test, to identify the main frequencies of the tower, considering its particular external restraint conditions, due to the presence of the church in the North-East corner and of the arch in the North-West corner. The study allowed the design of the new steel bell frame, which has been equipped with damped support, in order to reduce the forces transferred to the masonry walls by the bells’ movement. The stiffness of the damped supports has been carefully investigated to avoid resonance phenomena with the natural frequencies of the tower. After the completion of the restoration works and of the mounting of the new bell frame, a new dynamic test has been carried out in order to confirm the numerical model design results.