Collapse and damage to vernacular buildings induced by 2012 Emilia earthquakes

In May 2012, two seismic events hit the Emilia-Romagna Region, in Northern Italy. The earthquakes caused collapses and damage to traditional vernacular building heritage, highlighting its seismic high vulnerability. The paper presents a wide collection of damage and collapses observed in the aftermath field inspections on 22 historical vernacular buildings. It was noted that few recurring structural typologies are present in the area hit by earthquake and buildings of the same typology show similar damage mechanisms. Then, with the main goal to identify the most typical damage affecting similar structures, the building stock has been subdivided in different categories based on building plan distribution and intended use. The principal collapse causes, based both on in-field observations and analyses, performed on local and global finite element models, can be ascribed to poor connections between orthogonal walls, lack of effective connections between floor elements and walls, excessive flexibility of floor diaphragms and high slenderness of vertical elements. The outcomes in the present paper allow identifying the vernacular building typologies most vulnerable to earthquake and can help to plan the future retrofitting strategies for vernacular heritage.