Il ruolo della deformabilità degli impalcati sulla distribuzione delle azioni sismiche tra le pareti in edifici in legno a pannelli massicci

The paper presents the results of a numerical study aiming at investigate the influence of in-plane diaphragm stiffness on the distribution of the horizontal actions among the shear walls of cross-laminated timber buildings. In a statically indeterminate system, the distribution of lateral actions among the shear walls depends both on the behaviour of the connections between the timber massive elements of the diaphragm and on the lateral stiffness of the timber walls. In this study, timber floor diaphragms made of adjacent XLAM panels and connected with steel nails or screws are considered, while the seismic-resistant walls are made of XLAM panels connected at each floor and to the foundations by means of typical hold-down and angle-bracket connections. Numerical models are developed to investigate the role of several parameters on the distribution of the seismic actions among the shear walls, such as the stiffness of the connections between the panels, the building height, the in-plan layout and the dimension of the shear walls and of the slab.. The results point out that the diaphragm flexibility can entail significant differences, even larger the 100%, in the evaluation of the real actions with respect to the classical solution with rigid diaphragm.