Preliminary Studies on the Structural Behaviour of Traditional Timber Roof in Gjirokastra, Albania

The safety evaluation of an existing timber structure is a key task for maintaining it in service or not, by means of the definition and prescription of conservation measures and interventions. The knowledge acquiring process requires information on both geometrical and mechanical properties of timber members, as well as on the loads that the structure was and will be submitted to. Furthermore, because historic roofs are load-bearing structures made of timber according to a heuristic and an intuitive design without structural engineering theory support, analysis of their real structural behaviour is needed. Traditional roofs in Gjirokastra (Albanian UNESCO World Heritage), seem to be very peculiar in the Southern Western Balkans. The structures consist of a single main warping covered by timber planks and stone slabs of different sizes and thickness, placed without mortar or metal hook connections. Elements are connected to each other with nails in a very simple heel joint, considering the connection between horizontal beams and rafters, and an half-lap joint, concerning the connection between rafters and posts. Horizontal beams are nailed to the masonry's timber ties system, which horizontally reinforces the walls ensuring the overall box-like behaviour of the building. The paper proposes a FEM analysis of a first case study of these peculiar timber roof structures, preliminarily analyzed during the author’s Master Thesis’ degree in Architectural Engineering at the University of Genoa, which is now part of the author's ongoing PhD research titled "Traditional timber roofs in Gjirokastra, Albania. From knowledge to preservation".