Zapfenverbindungen im Holzbau – bruchmechanische Analyse und Vorschlag eines Berechnungsmodells

Timber-to-timber connections benefits in terms of the production and assembly process in structural timber engineering. In the past few years, the traditional mortise and tenon connection was adapted step-by-step on the CNC production process. New connection types as the dovetail connection enables a better installability and multiple tenon connections show significant higher loading capacity. Experimental investigations showed that all these connection types fail due to the crack propagation in grain direction. Transversal tension stresses combined with shear stresses as observed at the notch results in failure. In this contribution the failure load of tenon connections will be developed with the energy-based fracture mechanic method used in Eurocode 5. The new model shows good accordance to experimental investigations on tenon connections. A normalization of the experimental test results enabled a reliability analysis of the developed design equations. The proposed design equation is a modification of the Eurocode 5 formulation and allows to calculate the ultimate limit state of tenon joints.