Structural characterisation of laterally loaded glued and compressed wood dowel laminated timber portal frames produced using compressed wood connectors

Today, advanced production technologies using computer numerically controlled (CNC) tools are a key enabler of innovation in the mass timber industry. In addition, enhancement of the properties of wood using modification techniques, such as thermo-mechanical compression, is an emerging field. By combining the benefits of CNC tools and modified wood, this paper presents a novel timber-timber system using high-density compressed wood (CW) connectors suitable for mass timber beams-columns connections. This study details the materials and manufacturing processes of the developed connection systems and portal frames, followed by results of their structural performance (load carrying capacity, moment-rotation behaviour, connection stiffness and failure modes). Two frames were manufactured using conventional glulam members and tested under a lateral load and two further frames were manufactured using compressed wood dowel laminated timber (CWDLT) members which resulted in a 100 % wood and adhesives-free structural solution. The lateral load-carrying capacity of the frames with CWDLT members was relatively similar (4.4 % less) to the frames with glulam members, however, the mean stiffness of glued members was approximately 53.0 % higher than the frame with CWDLT members. The study has demonstrated a practical and sustainable all-wood connection concept that can be used in mass timber structures with CWDLT members as well as glulam members. The developed concept may lead to a substantial reduction in the use of synthetic adhesives and energy-intensive metallic connectors within timber structures ultimately increasing their sustainability and recycling potential.