Experimental investigations on the load-carrying capacity of digitally produced wood-wood connections

Abstract

The rise of digital fabrication has increased the use of wood-wood connections inspired by traditional carpentry in modern timber constructions. With recent developments on standard construction systems, the mechanical behavior of such joints for in-plane loading configurations is an essential parameter for the structural design. However, only few design guidelines exist on this topic in building codes such as Eurocode 5 and research has been mainly focused on the rotational behavior, which is important for free-form structures. Therefore, this work presents an experimental campaign on the load-carrying capacity of digitally produced through tenon connections for commonly available engineered timber products such as oriented strand board, laminated veneer lumber, and multiply solid wood panels. Shear and compression failure modes were studied and two test setups were developed. The scope of the study was limited to five different materials, a grain orientation parallel to the joint, and three different tenon lengths. The test results showed significant differences between the product specifications given by manufacturers and real performances observed for oriented strand board and cross laminated timber, while laminated veneer lumber had more accurate specifications. Nonetheless, a spreading of the compression strength was highlighted only for the OSB material and was also observed for the shear strength of laminated veneer lumber specimens. The existing Eurocode 5 guidelines generally underestimated the load-carrying capacity of the connections by 25% and only the capacity of oriented strand board connections was overestimated. Finally, the study demonstrates that different design approaches can be defined according to the material employed in through tenon connections. Design diagrams based on tests are preferred for materials with a high variability between product specifications and real performances while design criteria from building codes can be applied for the others.