Failures due to long term behaviour of heavy structures: the Pavia Civic Tower and the Noto Cathedral

The failure of monumental buildings is fortunately an exceptional event; nevertheless, when their safety assessment is required, any risk factor that may affect the integrity of the buildings has to be taken into account. Ancient buildings often show diffused crack patterns, which may be due to different causes in relation to their original function, to their construction technique and to their load history. In many cases it is simply the dead load, usually very high in massive monumental buildings, which plays a major role into the formation and propagation of the crack pattern. Some case histories are presented with more attention to the main collapses: the Civic Tower of Pavia and the Cathedral of Noto.