Experimental and numerical investigations on oak's potential: structural performance of glued-in rods compared to spruce

This paper investigates the structural performance of glued-in rods (GiRs) in oak, a wood species studied less in this context than the more commonly used spruce. The study systematically varies key parameters such as embedment length, edge distance, and group action to assess their impact on the load-bearing capacity and failure mechanisms. A comprehensive experimental program was designed, involving various configurations of single and multiple rod systems. Key findings reveal that oak's longitudinal tensile strength was recorded at 108.7 MPa, surpassing spruce's 98.2 MPa, which underscores oak's superior mechanical properties. In terms of failure mechanisms, oak demonstrated more ductile modes while spruce often experienced brittle failures like timber splitting. The prediction of load capacity employed a probabilistic approach based on Weibull's weakest link theory, effectively accounting for variability in material properties; observed load capacities closely aligned with predicted outcomes. Experimental results showed that for various configurations, oak consistently outperformed spruce in average shear strength and load capacities across different edge distances and embedment lengths. Overall, the findings provide valuable insights into the use of hardwoods in timber engineering, suggesting that oak could serve as a viable alternative to spruce in GiR applications.