Study and analysis of XIV century timber built-up beams in Verona

Starting from XIV century, a very interesting construction technique was developed in Northern Italy for heavy-loaded or long-span beams: these special timber beams are composed by an assemblage of multiple parts that behave practically as they were made by a single piece, thanks to a clever system of indentations, obtaining in this way the overall dimensions of slender thin-walled and high-section that could not be fit by cutting one single log. The first witness of this system can be found in Leonardo da Vinci's codes, but some examples of these beams can still be found in exercise, like those we discovered in an ancient palace in Verona, dating from XIV century. The study of the mechanical behavior of these beams is presented, taking into account the orthotropic properties of the wood, as well as some comparison with other beams found in Ferrara, together with the discussion of some proposal for their reinforcement in order to assure a safe reuse of the historic building. A sort of pre-stress can be depicted in Leonardo's drawings, in order to assure the connection of different pieces and the efficiency of the framework.