Laboratory tests and theoretical analysis of shear joints made of European birch plywood embedded in the CLT panels with European beech wooden dowels

This article presents a part of a broader study of the unique authors’ solution for the joints of the walls made of the CLT panels. The presented research concerns double shear butt joints with false tongue using the wooden, European beech dowels. They are joining the CLT panels and the load transferring European birch plywood embedded in the CLT panel axial plane, parallel to the lamellae. Also, an attempt was provided to estimate the strength of such connections using empirical models included in the new EN 1995-1-1:2025(EC5) standard. It was proved that in case when the assumptions of the EC5 are not met, i.e. the embedment depth is less than twice the diameter of the dowel, these models may lead to a significant overestimation of the load-bearing capacity of the wooden dowel connection. In particular, if the standard assumptions, such as ratio of the wooden dowel diameter to the dowel embedment thickness, are not met. Comparison of the results of the laboratory tests with the load-bearing capacity determined theoretically according to the models included in EC5 showed its overestimation in range of 23-51% in relation to the average tests’ values, and 51-86% in relation to the nominal tests’ values. Taking into account that the failure modes of wooden fasteners, due to the wood structure, may differ significantly from the metal ones, it is recommended to consider additionally also the Mode V of failure in the double plane shear joints with wooden dowels proposed by Miller et al. (2010).