Earthquake-induced damage assessment and partial failure mechanisms of an Italian Medieval castle

This paper investigates the seismic response and partial failure mechanisms of the Castle of St. George, one of the most renowned monumental constructions of the invaluable cultural heritage in Mantua (Northern Italy), which was hit by the 2012 Emilia seismic sequence. The first part of the study is based on historical analysis, documentary research, photographic collection and field surveys to achieve an accurate knowledge of the castle and a proper evaluation of the damage caused by the earthquake. All the collected information is used to create a representative and detailed finite element model of the castle and non-linear dynamic analyses are carried out using a damage plasticity model with different softening behavior in tension and compression for masonry. The finite element simulations provide additional information on the seismic response of the castle, identifying the damage patterns and the most vulnerable parts for different seismic intensity levels. The numerical results indicate that the corner towers and the vaults are the most damaged elements of the castle. The towers exhibit a severe damage concentration in the battlements, near the enlargements of the section in correspondence with the corbels and along the body near the openings. Moreover, the interaction between the tower and the adjacent walls, which are characterized by a different dynamic behavior, causes marked vertical cracks along the walls in correspondence with the connection regions.