Multi-mode failure of form-fitting timber connections – Experimental and numerical studies on the tapered tenon joint

Traditional carpentry joints with tapered tenons have been used widely in timber structures all over Europe to connect two structural parts under compression loads that concur at a somehow diagonal angle. When a change of use is required or when damages are obvious, then an analytical model is needed to prove the structural safety even for non-engineered connections. Experimental investigations and numerical modelling were carried out for the tapered tenon to back up the basic understanding of failure modes and strength. Three types of failure were considered: rolling shear failure, failure of the front side and failure of the bottom face. The influence of friction was examined systematically. Based on the results of the experimental studies, numerical studies were carried out using a cohesive zone model. Practical suggestions for the engineering design were derived from the research results.