Glued-in multiple steel rod connections in cross-laminated timber

The increasing popularity of cross-laminated timber (CLT) provides opportunities to extend the use of wood beyond traditional low-rise residential construction. For the high-performance material CLT to achieve its full utilisation, adequate joining techniques are required. With that in mind, while glued-in rods (GiR) are a powerful technical solution for numerous timber engineering applications, with proofed performance in solid wood, only few studies are available on the performance of GiR connections in CLT. Critical research gaps exist regarding the performance of multiple GiR, which this paper suggest to fill. Herein, experimental investigations on the performance of multiple GiR in CLT are presented. Steel rods of diameter d = 12.7 mm were glued-into CLT panels with two anchorage lengths (10d and 18d), three numbers of rods (1, 2 and 3), and two spacings between rods (s = 4d and 6d). In total, 10 test series with 5 replicates, thus 50 specimens, were manufactured and subsequently tested under uni-axial quasi-static monotonic tension. The results, assessed in terms of load-carrying capacity, demonstrated that GiR in CLT offer an alternative high-performance timber connection, and allows for more insights relating load capacity to the number, the anchorage length, and the spacing between rods.