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Mattia Carioti Characteristics of In-Plane Loaded Timber Roof Diaphragm Modelled as Orthotropic Plate 1 Abstract About the 60% of the existing buildings on Italian territory has been built using the technology of Unreinforced Masonry (URMB). Since half of them has been realized before 1919, it is reasonable to evaluate that the percentage of the existing URM buildings is about the 30% of the total amount of buildings currently standing in Italy. The construction technology of URM consists of clay-bricks walls as vertical elements and, in most cases, the floors are timber diaphragms with a floorboard layer perpendicularly nailed to joists that span between the walls. Since unreinforced masonry has scarcely predictable behaviour when subjected to seismic actions, and Italian territory is widely affected by seismic hazard, it is necessary to use the best accuracy in building strengthening and adequacy, with the aim to minimize the cost of losses. The damages observed during and after earthquakes in Umbria e Marche [1997], Abruzzo [2009] and Emilia [2013] have sadly confirmed the vulnerability of Italian URM buildings. In the first chapter the most common failures and damages regarding URM due to seismic actions will be classified and perused, and Secondly, the most damaging weaknesses will be discussed and the most suitable interventions for URM will be higlighted, according to the literature and articles: increase of in-plane stiffness of diaphragms and improvement of connections between horizontal diaphragms and lateral walls. Hereafter an experimental campaign carried out in EUCENTRE laboratories at University of Pavia between 2010 and 2012 will be summarize to show the seismic behaviour of three two-storey rock masonry buildings, with increasing seismic-adequacy interventions, subjected to seismic excitation through vibrating table. The better reponse of buildings with higher in-plane stiffness and better connected elementes will prove relevant and therefore thorougly specified. After a comprehensive and detailed review of literature regarding the methods already available for the detection of in-in plane characteristics of diaphragms, the mechanical characteristics of the floors present in the sample buildings of the experimental campaign using real experimental data. The Tremuri software will be used to create an equivalent frame model of the URM building tested in the Pavia experimental campaign, representing the floor diaphragms as an equivalent orthotropic plate, using the mechanical properties of different retrofitted floors gathered from the outcomes of the experimental campaign. The actual software model will be tested according to the methods provided by Italian Code (NTC08): pushover analysis and dynamic non-linear analysis. In the end the study will offer the results of the following model by inquiring the following aspects: • maximum displacement of a control point • maximum shear request at base of building • energy dissipation of the building • general building stiffness • damage pattern of shear walls eventually assessing the dissimilarities between my software model and the software processing proposed by Penna et al [2014] and the experimental results following the 2012 Pavia Campaign.
