Seismic structural upgrade of historical buildings through wooden deckings strengthening: the case of study of Palazzo Ducale in Parete, Italy

Aim of this article is to study the structural improvement of a historical wooden deckings using additional wood structural members and wood restoration techniques. Renovation of historic constructions, often performed for intended new use of buildings, cannot and must not disregard the conservation not only of the elements function, but also of materials and construction techniques. They all represent, indeed, an inestimable cultural heritage. In this context, it is paramount to seek structural improvements in deformation and strength capacity of wooden structures through the use of modern techniques compatible in typology with the original materials and construction techniques. This paper presents the case study of the wooden deckings restoration in the "Palazzo Ducale di Parete", Italy. The palace, located in the historical centre of the city of Parete in the province of Caserta, is composed of a central core (defensive tower), built probably between XI and XII century, and adjaciance blocks added in the following centuries. Apart from the central tower that rises above the rest of the palace, the building is comprised of three levels above the ground and a mezzanine. The wooden deckings were probably built before the 1700 with chestnut wood and made of a primary beam system of 25 cm diameter circular section beams, and a secondary floor distribution system with semicircular transversal elements named "panconcelle" loosely connected to beams. Structural improvement intervention consisted in the realization of a double timber crossed plank in chestnut wood, connected to principal frame through metal cylindrical shank pins, suitably sized. Where possible, the "panconcelle" were not removed from their seat to preserve the original intrados view of the floors.