"Non-linear modelling of wooden light-frame and X-lam structures"

Cross-laminated (‘X-lam’) timber panels and light-frame structures represent a new effective construction technology, with significant potential for multi-storey earthquake-resistant buildings. Despite the extensive use of these systems, there is a lack of design methods to evaluate the capacity in terms of dissipated energy and global response under cyclic loads. In the paper a method that allows an accurate evaluation of the energy dissipated by a subassembly made of X-lam panels connected to each other and to the foundation with metal fasteners is proposed. The X-lam panel is regarded as linear-elastic and all dissipated energy is assumed to take place in the connections. Appropriate user elements are implemented in the ABAQUS software package as external subroutines for different metal connections, such as screws, angle brackets, hold-downs and others. These elements allow the user to implement a hysteretic behaviour with pinching very close to the experimental results with allowance for strength and stiffness degradation. The model was calibrated and validated on cyclic tests carried out at CNR-Ivalsa on single X-lam walls connected to the foundation. The model was then extended to light-frame structures. These numerical models were able to predict the correct cyclic response in terms of deflection and energy with an overall good approximation.