Some experiences about the retrofitting of tower masonry structures

The paper deals with some intervention methodologies for tower structures belonging to the architectural Italian heritage, aimed to the reduction of the collapse risk under normal and exceptional loads. Then the special investigation for evaluation of the structural safety of the bell tower of Palermo Cathedral and the following collapse risk mitigation are described. First through the paper the history of the tower is presented then in situ and laboratory tests are described. The interventions adopted after the investigation are discussed and finally the dynamic tests for the validation of the analytical model used in the assessment of the seismic vulnerability are showed.