Flexural behaviour of timber dovetail mortise-tenon joints

A comprehensive study has been carried out on the flexural behaviour of dovetail mortise-tenon joints in timber structures. Two types of the joints have been considered; type 1 represents a joint at the top of a column where the beam tenon may be slid into the mortise from above the column, and type 2 represents a joint below the top of a column where the beam tenon needs to be inserted from the side into the mortise. Relationships of moment vs. rotation and tenon pull-out vs. rotation, as well as the failure modes were obtained from experiments under monotonic loading. Numerical simulation was conducted to examine the deformation states and the stress distributions. On the basis of the experimental and numerical data, a simplified mechanics model has been proposed for the analysis of the moment vs. rotation relationship. Results show that the main failure mode of the dovetail joints is pull-out, and due to the dovetail shape on the two sides of the tenon, the side gaps tend to have a more significant effect than the gaps at the top and the apex. The moment-rotation relationship of the joints has an initial stage of gradual development of nonlinearity, followed by a prolonged yielding phase, and then a descending branch. The moment-rotation relationship may thus be approximated by a trilinear model. Simplified formulas for determining the key points on the moment-rotation relationship have been shown to agree well with the experimental results. (c) 2016 Elsevier Ltd. All rights reserved.