The truss bolted: an ancient earthquake-proof system

The Church of Santa Maria della Misericordia, situated in the inhabited center of Bourbon, while being a simple building, is distinguished for its walls facies from XV-th century and particularly from the roof made according to a special technique of L'Aquila, which was developed after the earthquake from1703, using the system of "truss bolted". This truss plays a function of containing that makes the entire building more resistant to the horizontal action of the earthquake preventing the overturning of the walls. In fact the building of St. Mary from the '500 onwards has resisted to various earthquakes without reporting significant damage. It was in fact detected in time, only some longitudinal lesions in the vertical structures, which have recently been consolidated with hinging in aramid fiber. But the more attractive system, known previously and discovered during the L'Aquila earthquake, remains one of the truss bolted, earthquake-proof system, found in many churches in Abruzzo. These trusses, as they have been conceived, have resisting for three centuries and more than earthquakes and natural events, also taking together the chest walls of the Church, that which did not report damage even after the earthquake in the nearby city of L'Aquila in 2009. In this work, developed following the process of cognitive diagnostic plan, they are explain the peculiarities of the construction system, consisting of the truss bolted, referring to a real example found in the Church of Santa Maria in Bourbon.