Embedding strength of fully-threaded dowel-type fasteners in cross-laminated timber: an experimental study

Abstract

The purpose of this paper is to experimentally evaluate the embedding strength of dowel-type fasteners in Cross-Laminated Timber (CLT), observing the effect of lamellae orientation and the dowel diameters. Thereby, CLT specimens – with three layers of lamellae – and solid timber specimens were produced and tested under loads at 0º and 90º with the direction of the grain, considering five dowel diameters. The results showed that CLT embedding strength depends on the dowel diameter in the two investigated directions. The CLT embedding strength parallel to the grain was up to 8% lower than those for solid timber in the same direction, and up to 26% higher than the solid timber strength in the perpendicular direction. The analysis of variance (ANOVA) showed no significant difference between the mean values of the CLT and solid timber embedding strengths, except for the embedding strength perpendicular to the grain found for 16 mm dowel diameter. When comparing the results obtained experimentally with those determined analytically, the equation proposed by KENNEDY et al. (2014) led to a better agreement, for both the loads applied at 0º and 90º to the grain direction.

Keywords: Cross-laminated Timber; Dowelled connections; Embedment strength; Half-hole embedment tests; Design approaches.