Damage observation and settlement mechanisms in the naves of the Cathedral of Milan

The Cathedral of Milan is studied in relation to the observed damage and structural system configuration in the nave and aisles. The damage results from relevant events in the history of the construction, ageing of the structure, soil settlement, vibrations, environmental conditions, corrosion, etc. Information was gathered on damage in the vaults, arches and iron ties, on the basis of new observations compared to the documentation related to the repairs carried out in the 20th century. Based on the observation of compression, tension and sliding cracking (mechanisms or damage) the relevant settlement mechanisms are discussed. The data of the monitoring systems available since 1966 provide information about the foundation settlements and column verticality, caused by lowering of the water table in the 20th century and slowly continuing at present. The present damage in the structure has been compared to the corresponding damage of arches and vaults related to equilibrium load path calculations and settlement mechanisms in limit analysis theory. The results provide an interpretation of the causes of the damage and provide a basis for the planning of future monitoring and interventions.