Temporary structures used for the retrofitting and the maintenance works of the Asinelli Tower in Bologna, Italy

Located in the heart of the city of Bologna, in Italy, the two medieval masonry towers (called “Due Torri”) represent the main symbol of the city itself. The results obtained by a wide and complete experimental inspections campaign, showed that a reinforcement design of the elevation structure of the Asinelli Tower was absolutely essential, and this plan had to be divided into two different and consequent steps: Step 1 (2011) is about the reinforcement of the first part of the elevation of the tower (up to 35m in elevation), Step 2 is the consolidation of the higher part of the tower (up to 97m). This paper focus on balancing the pros and cons of three possible different temporary structures which can be used to allow the retrofitting plan: (1) a steel 100m high scaffolding, (2) a suspended steel platform, (3) a lift crane laid on the basement of the tower.