Rigid or flexible? A numerical investigation on the in-plane behaviour of CLT floor diaphragms

The in-plane stiffness of floor diaphragms is an important property of building structures which should be carefully considered during the design stage. Few studies on the in-plane behaviour of cross-laminated timber (CLT) floors are available in the literature, without providing a consistent method to evaluate the in-plane stiffness of this type of floors. This paper presents a study of the in-plane flexibility of cross-laminated timber floors aimed to define their behaviour as rigid or flexible, as is typical in structural engineering. A parametric analysis is performed, by varying geometry and mechanical property of a reference CLT building, by means of numerical models implemented in SAP2000. Results in terms of displacements and lateral loads distribution are compared with reference factors of several standards, identifying the conditions where floors can be considered as rigid.