The use of cross-laminated timber (CLT) in residential and non-residential buildings is becoming increasingly popular in North America. While the 2016 supplement to the 2014 edition of the Canadian Standard for Engineering Design in Wood, CSAO86, provides provisions for CLT structures used in platform type applications, it does not provide guidance for the in-plane stiffness and strength of CLT shearwalls. The research presented in this paper investigated the in-plane stiffness and strength of CLT shearwalls with different connections for platform-type construction. Finite element analyses were conducted where the CLT panels were modelled as an orthotropic elastic material, and non-linear springs were used for the connections. The hysteretic behaviour of the connections under cyclic loading was calibrated from quasi-static tests; the full model of wall assemblies was calibrated using experimental tests on CLT shearwalls. A parametric study was conducted that evaluated the change of strength and stiffness of walls with the change in a number of connectors. Finally, a capacity-based design procedure is proposed that provides engineers with guidance for designing platform-type CLT buildings. The philosophy of the procedure is to design the CLT buildings such that all non-linear deformations and energy dissipation occurs in designated connections, while all other connections and the CLT panels are designed with sufficient over-strength to remain linear elastic.
A new type of mass timber structural system has been developed in New Zealand over the last decade. Timber members made of engineered wood products are used in combination with post-tensioning cables to produce highly efficient structural components suitable for multi-story moment resisting frames or shear wall-based lateral load resisting systems. Both systems are particularly useful in structures designed in high seismic regions. The post-tensioning also ensures self-centering of the components and the structural systems after a seismic event. In addition to the post-tensioning, the systems can use energy dissipating devices within the connections that further enhance the ductility of the systems and make them good candidates for low damage structural applications. Extensive experimental and numerical studies have been conducted to determine the performance of these systems and design procedures have been developed for practical applications. In an effort to bring this system closer to the North American designers, this paper contains a summary of the evolution of the concept and the most important research projects and findings to date. In addition, a number of applications within and outside New Zealand are reviewed to demonstrate the applicability of the concept. Finally, potential and recent initiatives for adoption of the technology in North America are discussed.