Modern mass timber braced frames rely on connection yielding to provide ductility and energy dissipation capacity under earthquake loads. However, the ductility and energy dissipation capacity of steel dowel connections can be limited by the onset of a brittle failure mechanism in the timber (e.g., row-shear, group tear-out, or tension failure) prior to significant dowel yielding. To address this challenge, this paper presents experimental results on the structural performance of timber-steel dowelled connections reinforced with self-tapping screws. Four full-scale connections were tested under monotonic loading with and without reinforcing screws. The tested connections had two internal steel plates that were fastened to the timber using steel dowels. The unreinforced connection was intentionally designed to exhibit a brittle row shear failure prior to yielding of the steel dowels. Results of the study demonstrated the brittle nature of row shear in timber connections and the potential for using self-tapping screws to promote a more ductile failure. While the unreinforced connections exhibited no ductility, the reinforced connections had an average ductility of 4.8. Overall, results of this study demonstrate the potential for using self-tapping screws to retrofit and reinforce a timber-steel brace connection for situations in which a connection may be predisposed to brittle row shear failure.
