Synopsis
Bonded-in rod timber joints offer several advantages over conventional types of joint, including high local force transfer, very stiff connections, and improved fire and aesthetic properties since the connection is completely hidden in the insulating timber members. More recently, the use of fibre reinforced polymer (FRP) as a connecting rod, alternative to steel rods, in bonded-in rod connections for timber structures has been investigated. However, the investigation into the behaviour of such joints is limited, in particular, connections involving basalt fibre reinforced polymers (BFRP) bars – which is the primary focus of this research. This paper presents an experimental programme conducted to investigate the behaviour of bonded-in BFRP bars loaded parallel to the grain of glulam members. Tensile pull-out tests were conducted to examine the effect of bonded length and bond stress-slip on the structural capacity of the connection. An analytical design expression for predicting pull-out capacity is proposed and the results have been compared with some established design equations. It was found that pull-out load increased approximately linearly with the bonded length, up to maximum which occurred at a bonded length of 15 times the hole diameter, and did not increase beyond this bonded length. The most significant failure modes were failure at the timber/adhesive interface followed by pull out of the BFRP rod. Increased bonded lengths resulted in higher bond slip values compared to lower equivalent bonded lengths. The proposed design model gave the best predictions of pull-out capacity compared with other existing models.