The Italian historic building heritage is characterized by the use of elements and/or timber components for the construction of roofs and floors of masonry buildings. In other cases, the timber is used in medium-sized structures, such as single or multi-family buildings, even with a multi-storey configuration, mainly built using the structural types derived from the local techniques. In recent decades, the Italian territory has been affected by the fast spread of multi-storey buildings and residential complexes entirely built with timber elements. The buildings have been constructed primarily using modern construction techniques, even in areas with a medium-high seismic hazard. Many of these buildings have been designed without established procedures and, not infrequently, even neglecting the safety verifications related to the earthquake effects. The problem of the seismic vulnerability of timber structures, also in relation to a possible damage after the earthquake, can prove to be significant as demonstrated, for example, by the 1994 Northridge and the 1995 Kobe earthquakes [Karacabeyli and Popovski, 2003]. Specifically, sometimes the structural damage following an earthquake can permanently compromise the safety of the structure and make impractical (economically sustainable) every possible repair intervention after the event. Having procedures and coded tools to evaluate the safety status of the existing structures and to quantify the level of seismic hazard has therefore become a matter of primary importance to fulfil the tasks of the civil protection system of a State.