## 2 Materials and Methods  
### Experimental Test  
European beech (_Fagus sylvatica_ L.) solid wood from Austria was used in the experimental tests. The boards were obtained from heartwood and cut in the tangential direction. Before testing, the boards were conditioned in a climatic chamber at 20 \({}^{\circ}\)C and 65% relative humidity until equilibrium moisture content (MC) was reached. After conditioning, all boards were visually graded according to the German standard DIN 4074-5:2008 [48]. The specimens were free from knots and cracks. All specimens met the requirements for the LS13 strength class [48], which would allow a strength class assignment of D40 according to EN 1912:2012 [49]. MC was determined using the oven-drying method using a section taken from each board following EN 13183-1:2002 [50]. This resulted in an average value of 10.3%. The density (\(\rho\)) was also measured using a section taken from each board according to EN 408:2012 [51] and adjusted to the reference moisture content of 12% [52], giving a mean value of 732 kg/m\({}^{3}\). The beams were subjected to 3- or 4-point bending tests depending on the connection layout studied (Figure 1), at a constant crosshead displacement rate set between 0.75 and 3.50 mm/min, so that failure took place in approximately 5 min. Displacements (\(\delta\)) were measured using linear variable differential transformers (LVDTs) and recorded at a frequency of 1 Hz during the tests. To analyse joint behaviour and dowel sliding, LVDTs were placed both at the bottom of the loading plates, as close as possible to the dowel, and at the bottom of the beam (black triangles in Figure 1). Holes of the same diameter as the dowels were drilled in the timber beams so that there was no clearance between them. Figure 1: Bending test set-ups. The experimental programme was divided into two groups of specimens according to the beam depth (\(h\)): group 1 with \(h\) = 100 mm and group 2 with \(h\) = 200 mm. The beam width (\(b\)) was 48 mm for all specimens. In all tests, dowels with a diameter (\(d\)) of 16 mm and 120 mm length made of S355-grade steel were used. With this diameter, the dowel slenderness (\(b\)/\(d\)) was small, and steel yielding was avoided. The distance to the loaded edge (\(h_{e}\)) was set at 4\(d\) (minimum distance established in Eurocode 5 [24]), remaining constant in all tests, resulting in joints with two different values of the \(\alpha\) parameter (\(\alpha=h_{e}/h\)), namely 0.64 for group 1 and 0.32 for group 2. In each of the groups, beams with one dowel (1D) and two dowels (2D) were tested in order to analyse the influence of the number of dowels and connections on the splitting capacity. As a reference configuration, a span \(L\) of 950 mm (1000 mm specimen length) and one connection with 1D and 2D (spaced \(a_{r}=4d\) apart) located at mid-span were established. In order to analyse the influence of the distance \(l_{b}\) from the connection to the support and the distance \(l_{c}\) between the connections on the splitting capacity, different \(l_{b}\) values were considered (360 mm, 240 mm, and 120 mm), which corresponded to support spacings of approximately 0.38, 0.25, and 0.13 times the span. In order to also analyse the influence of the slenderness of the beam on the splitting capacity, beams with the connection at mid-span but with \(L\) of 450 mm (500 mm specimen length) were also tested. Figure 2 illustrates the set of reference configurations and their variations. Table 1 summarises, for each series of tests, the geometrical parameters of the beam (span and depth), as well as the density and moisture content, the position of the connection in terms of distance to the support \(l_{b}\) and the spacing between connections \(l_{c}\) (in case of two connections), the position of the connection in relation to the beam depth by means of the \(\alpha\) parameter, and the number of replicates tested.