Performance of reinforced-concrete residential buildings during the Emilia (Italy) 2012 Earthquakes

At the end of May and at the beginning of June 2012, the Emilia Region of Northern Italy was struck by a seismic sequence, with two main events of local magnitude ML 5.9 and 5.8. The earthquakes caused significant damage to industrial, monumental, rural buildings and, to a lesser extent, to bridges. The present study is focused on the failures suffered by reinforced-concrete residential buildings. A description of the damage observed during field surveys is given and the interpretation of the structural performance is conducted considering the characteristics of both the earthquake-induced demand and the building vulnerability. Most of the constructions surveyed were not designed to withstand seismic actions, because the zone was not classified as a seismic-prone area until 2003. Failures are similar to what is observed typically in Mediterranean earthquakes in structures designed for gravity loads alone. In the collapsed reinforced-concrete buildings, the failure has been determined by a combination of soft-storey mechanism, local effects related to poor infill arrangement, inadequate details. In several buildings, damage to non-structural elements has been detected.