In the perspective of seismic engineering the adoption of Capacity Design principles requires that ductile failure mechanism take place before the failure of brittle members. This work investigates the causes and implications of the hidden reserve of strength that could compromise this behaviour for Cross Laminated Timber structures. In the first chapter an introduction to the basic concepts behind Capacity Design philosophy and how these apply to timber buildings is presented. Furthermore, an overview on how the Capacity Design principles are treated by the building codes of Europe, Canada and New Zealand is presented and discussed. In the second chapter, the methods and results on how the overstrength factor has been so far calculated in the literature for timber building are reported and discussed. A comparison has also been made between the techniques used to evaluate the overstrength factor for other common building materials and timber. The third chapter treats the planning and the execution of the experimental tests performed in the university’s laboratory. After a description of the material, equipment and methods used for the tests, the outcomes of the investigation are presented and discussed. Finally, in the concluding chapter the implications of the results are critically discussed and a suggestion on how to assume the overstrength factor is presented. Moreover, some suggestion on how future research could further investigate the matter are also given.

M-BA