Load-slip behaviour of glue laminated timber connections with glued-in steel rod parallel to grain

Abstract

This paper reports experiments performed on glulam connections with glued-in single steel rod to investigate the joint behaviour. A total of 68 glulam joints with glued-in steel rod were tested via pull-pull tests. Experimental variables include the bar diameter, bonded length, glue-line thickness, angle with respect to the grain, species, adhesive type, and rod type. The results indicated that the failure modes were classified as rod pull-out failure, rod yielding, timber splitting, and timber shear failure. The ultimate capacity and stiffness of the joints were mainly influenced by the rod diameter, bonded length, adhesive type, and rod type. Once the bonded length was ＞12.5d (rod diameter), the glued-in rebar joints usually failed by bar yielding and both the angle with respect to the grain and the bond-line thickness showed little influence on the joint ultimate capacity and stiffness. The joint ductility coefficient calculated based on the proposed equivalent energy-based method ranges from 2.9 to18.0 indicating that the glued-in steel rod timber joints can show considerable ductility with reasonable design. Finally, a proposed bond–slip model considering the rod-yielding effect was used to predict the bond–slip behaviour of the tested joints.