Moment resisting connections composed of friction-welded spruce boards: experimental investigations and numerical strength prediction

Research on friction welded wood-to-wood connections has shown high potential for further development regarding the industrial application of timber construction. This paper addresses the question to which extent welding of wood can be applied to fabrication of cross-laminated timber panels (CLT). Those panels can be used as wall elements, in which load transfer occurs by transmission of moments and shear stresses. For this purpose, experimental investigations on friction welded L-shaped specimens were carried out. The welded bond between the boards, arranged perpendicularly to their fibre directions, represents points of intersection of those CLT panels. The results allowed for (a) the determination of a fracture mechanism of welded timber connections under torsion, (b) the definition of a set of design parameters influencing the resulting joint strength and (c) the comparison between the performance of welded timber joints and those of commonly glued alternatives. The experimental investigations were compared to results obtained by numerical modelling, thus allowing a probabilistic strength prediction algorithm for predicting the joint capacity as a function of the surface size.