Seismic resistance of existing buildings with added light timber structure storeys

In the presented paper, the problem of vertical expansions is treated in terms of seismic resistance of structures with added storeys. A large parametric study has been performed, confirming the impact of different number of added storeys, and the change of their stiffness, on the seismic response of structures. The paper shows examples of how stiffness in light timber frame and cross laminated timber structures can be easily altered just by changing the type and distribution of fasteners. Known procedures are used to calculate the stiffness of the wall elements of a light timber frame system, and a new procedure is developed for determining the stiffness of cross laminated timber wall elements. The study shows how changing the stiffness of the vertical expansion can have a significant impact on the seismic response and that, in some cases, vertical expansion can have a favourable effect on seismic resistance, despite a minor increase in the mass of the structure.