Performance of innovative adhesive-free connections for glued-laminated timber under flexural load

Timber, a renewable resource with a low carbon footprint, has a giant potential to replace reinforced concrete (RC) structures in housing, which can decrease the environmental impact and lead to a healthier construction work environment. However, connections, as part of timber frames, are majorly made of steel and adhesives, which emit harmful pollution and negatively impact the timber structures. This study focuses on enhancing sustainability in construction by proposing adhesive-free timber connections for glued-laminated timber (glulam) panels. The study aims to contribute toward sustainable construction practices by reducing the reliance on adhesives and exploring alternative connection methods for glulam panels. This article presents four-point out-of-plane bending tests on glulam panels with innovative adhesive-free timber connections. The studied specimens compromised fabricated glulam panels and densified wood connectors made of pine and beech, respectively. Six different adhesive-free wood connections were designed and applied independently. Each connection was connected to two glulam panels by their end-grain sides. Therefore, twelve glulam panels, connected using these six connections, were tested. The panels had identical dimensions and materials. The connections were applied at the mid-span of the two connected panels. The experimental results on the flexural behavior, ultimate load, strength, and displacement of the six specimens are presented. The obtained mean load-carrying capacity of the specimens in the current research was greatly higher than that of the other specimens with different timber connections, such as timber-timber connections using compressed wood connectors. Additionally, the failure modes of the specimens were analyzed, which mostly exhibited the shear failure and delamination behavior. Most of the tested specimens failed in a ductile manner with a high ductility, which is suitable for the earthquake regions. The findings demonstrated the potential of using adhesive-free timber connections in glulam panels and contributing to the development of zero-energy buildings and sustainable construction practices while maintaining the structural integrity.