Improved performance of reinforced rounded dovetail joints

• Rounded Dovetail Joints (RDJ) are a viable option to connect timber members.
• Structural performance of hand- and machine routed joints is similar.
• Design equation for RDJ yields conservative predictions.
• RDJ performance can be improved through reinforcements.

The paper presents experimental investigations on different methods to increase the stiffness of Rounded Dovetail Joints (RDJs). Departing from a reference geometry, the specific methods were (i) oversizing the dovetail tenon part for a tighter fit; (ii) reinforcement with self-tapping screws; (iii) reinforcement with an adhesive layer; and (iv) a combination of adhesive layer and self-tapping screws. The specimens from the reinforced test series were compared to regular RDJ specimens and to beam to joist connections by means of self-tapping screws only. It was demonstrated that all methods significantly increased the joint stiffness of RDJs. Furthermore, the research showed that there is no difference in structural performance between hand-routed joints and CNC-routed joints, and that a previously suggested design equation for RDJs yields conservative predictions when compared to the experimentally obtained 5th percentile values.