Analysis of the seismic safety condition of the defensive walls of Cittadella

Known as the “walled city”, Cittadella is located in the Veneto plain and it is a small medieval village surrounded by an elliptical-shaped defensive wall with an average height of 14 meters. A preliminary investigation on the seismic safety condition of Cittadella's walls has been developed with the kinematic analysis approach considering both the out-of-plumb configuration due to rotation at the foundation level occurred in the past and the retrofitting reinforcements carried out for some zones of the N-E walls. The obtained results clearly underline the vulnerability of the defensive walls toward the expected seismic events and, at the same time, highlight the relevant role of the provided interventions in reducing the seismic risk of the parts of walls characterized by relevant values of the out-of-plumb. According to the current indications contained in the Italian code, the use of the nominal life as parameter to evaluate the seismic safety level for historical buildings of cultural heritage is useful to identify a monitoring program aimed at preserving the integrity of walls and, at the same time, identifying suitable interventions.