Timber joints with multiple glued-in steel rods and the impact of defects
Most previous research on timber joints with glued-in rods has focused on testing joints with perfectly centred single rods to evaluate the influence of design parameters such as rod diameter and anchorage length on the connection's structural performance. In practice, however, multiple steel rods are required to transfer the loads from one structural component to the next and on-site manufacturing often leads to joints with the rods not being perfectly centred. This paper describes experiments were first the influence of the anchorage length was studied to establish performance benchmarks. Then a) joints with multiple rods (two, three and four rods with the spacing between rods varied) and b) joints with two types of defects likely to be encountered on-site (rods placed at an angle inside drill hole instead of aligned with the joint axis and rod placed against the side of the drill hole instead of fully centred) were manufactured and subsequently tested under uniaxial quasi-static monotonic tension load. The results showed that for joints using multiple mild steel 12.7 mm glued-in rods, a ductile failure can consistently be attained if: i) the anchorage length of the rod is longer than 10 times the diameter; and ii) the spacing between rods is five times the rod diameter.