## 3 Results and Discussion
### Comparison between Experimental, Numerical, and Theoretical Failure Loads  
The adequacy of the numerical and design models described in Sections 2.2 and 2.3 for the prediction of the splitting failure loads of beech beams loaded perpendicular to the grain by the connections is discussed here in relation to the experimental results. The material properties of the European beech used as input values in the models were also presented in Section 2.2, which corresponded to the tangential direction of the wood as this was the main orientation of the cross-section of the beams. Figure 14 shows representative results of the experimental (grey lines) and numerical (black lines) load-displacement curves, depicting both the dowel displacement (dashed lines) and the beam bottom face displacement (solid lines). As can be seen, the numerical results agree well with the experimental results for the main parameters, such as stiffness and ultimate load. Still, the numerical curves were able to better reproduce the experimental behaviour of the beams with a brittle failure than those with a mixed-mode failure pattern (see Figure 5). The good agreement between the experimental and numerical initial stiffness shows that the average values of the elastic constants used are representative of the material. This consistency between the numerical and experimental initial stiffness is more evident in the curves plotted considering the displacement of the bottom of the beam than in those plotted with the displacement under the dowel, where the numerical ones show a higher stiffness. The maximum splitting capacity of the geometries of group 1 (\(h\) = 100 mm) matches the experimental results, but in the case of group 2 (\(h\) = 200 mm), the predicted loads are always lower than the experimental ones. It should be highlighted that the expression in Eurocode 5 [24] focuses on the prediction of the maximum shear force, so the maximum splitting capacity of the connection has been obtained by applying beam theory. Thus, the maximum splitting capacity foreseen by Eurocode 5 [24] is twice the value of the shear force (Equations (14)-(17)) for all series, except for series 1D with the connection located at off-centre of the beam, where the maximum load carrying capacity was determined according to the following expression:  
\[P_{\text{pre}}=V_{s,\text{max}}\frac{L}{L-l_{b}} \tag{27}\]  
where \(V_{s,\text{max}}\) is the maximum shear force obtained directly from Equation (14), \(L\) is the beam span, and \(l_{b}\) is the distance from the connection to the nearest support. It should be  
Figure 14: Representative experimental and numerical \(P\)-\(\delta\) curves: (**a**) series with \(h\) = 100 mm (100/1D/950/0.13L); (**b**) series with \(h\) = 200 mm (200/1D/950/0.13L). noted that only Eurocode 5 [24] and the numerical models take into account the position of the connection with respect to the beam. The results of the predicted failure loads from the numerical finite element analysis and the three design models studied are presented in Table 6. The predicted values normalised to the experimental results for all cases are also included. These ratios are also shown graphically in Figure 15. A ratio \(\leq\) 1 represents a safe prediction and a ratio > 1 an unsafe prediction. As can be seen from the results, in general terms, the best theoretical predictions were found for low experimental loads (between 20 and 35 kN), and there was more dispersion at higher experimental loads (between 45 and 60 kN). When the connection is located at the centre of the beam (\(l_{b}\) = 0.5L), all models provide safe predictions for all the cases studied (one and two dowels and the two beam edges). Specifically, in the case of one dowel (1D), the Eurocode 5 base model and the Jensen model similarly give the best predictions.