Collapse mechanisms of churches: typical recurrence rates and damage levels from the analysis of field data after the 2012 Emilia earthquake

Abstract

Within the context of fast procedures for the evaluation of seismic damage, an interesting tool is given by the special form in use for churches. The procedure implemented in this form is based on the set of 28 local collapse mechanisms which have been identified as meaningful to deal with the typical Italian configuration of churches; for each mechanism, a damage level from 0 to 5 has to be specified and a global damage index is therefore computed. An interesting application of the above procedure has been possible for a wide group of churches in the province of Mantua, which suffered damage from the 2012 Emilia earthquake. Specifically, it has been possible to access data and analyze 159 forms. Through a detailed analysis of them, it has been possible to define, for each different collapse mechanism, the recurrence rate and the corresponding distribution of damage levels. In this way, it clearly appears, on the one side, which mechanisms are likely to be activated and, on the other side, in which cases high damage levels can be easily reached. This kind of analysis has resulted into a clear picture of the architectural typologies and construction techniques in use in the region; moreover, suggestions have come in terms of seismic prevention, as clear evidence has been given to the damage mechanisms which are more likely to be activated.