## 3 Results  
The results can be discussed in accordance with the physical model description given in the final paragraph of Section 2. The surfaces of the two connecting angles were previously \"whitened\" in all cases. Figure 10: Views of the element-angle surfaces of model III’s screw junction after destructive testing: (**a**) lower friction joint; (**b**) upper friction joint. (a) These tests were carried out on a bench (see Figure 1), with models as shown in Figure 3a. The surfaces of the two connecting angles were additionally \"kneaded down\" with spacer-bearing rings by tensioning the M16 bolt three times to a force value of F\({}_{\text{pM16}}\) = 98.9 kN + 2.5%. This value was practically equal to the preload force value F\({}_{\text{pM24}}\) = 222.5 kN for the M24 bolt at a scale of k\({}_{\text{F}}\) = 2.25, resulting from a scale of k\({}_{\text{I}}\) = 1.5. Each of the models was loaded five times with a vertical force, increasing in 10.0 kN increments in five steps until reaching a value of 50.0 kN, which is close to the frictional force limit, F\({}_{\text{uT2M16}}\), for models using M16 bolt ring data (d\({}_{\text{pM16}}\) = 45 mm, d\({}_{\text{pWM16}}\) = 17 mm; see Figure 2a):  
\[\text{F}^{\prime}{}_{\text{uT2M16}}=\mu\times\text{F}^{\prime}{}_{\text{pM16}} =49.5\text{ kN (for coefficient of friction }\mu=0.5) \tag{1}\]  
During each test, the strain gauge measuring point readings on the surfaces of the two joined angles and the inductive sensor readings of their relative displacements were recorded (Figure 5). (b) These tests were carried out on the same bench as the one used in the loading tests on model I. The models were loaded with a vertical force, quasi-statically increasing in 10 kN increments in successive steps until reaching the failure effect (friction joints), defined as the inelastic mutual displacement of their connected angles without an increase in the external load. The force F\({}_{\text{M16}}\) theoretically destroyed this joint, which was determined using ring data for an M16 bolt (d\({}_{\text{pM216}}\) = 45 mm, d\({}_{\text{pWM16}}\) = 17 mm; see Figure 2a):  
\[\text{F}_{\text{M16}}=\text{f}_{\text{tu}}\times\text{A}_{\text{sF2M16}}=385.5 \text{ kN} \tag{2}\]  
\[\text{where A}_{\text{sF2M16}}=\pi([\text{d}_{\text{pM16}})^{2}-(\text{d}_{ \text{pWm16}})^{2}]/4=1363\text{ mm}^{2}\]  
\[\text{f}_{\text{tu}}=283\text{ N}/\text{mm}^{2}\]  
During these tests, the readings at the same measuring points as those used in the load tests were recorded, and similarly, these readings were averaged to determine the results of the destructive tests. (c) These tests were carried out on the same bench as the one used in the load tests, but this time with the model III connection nodes according to Figure 3. The surfaces of the two connecting angles were additionally \"crumpled,\" and the M16 bolts had been pre-tensioned to the force value F\({}_{\text{pM16}}\) = 98.9 kN, with an accuracy of + 2.5%. The loading tests on physical model III were similar to those performed on model I, but model III was tested in a loading arrangement with a vertically increasing shear force, F, and additional forces, F\({}_{\text{Mz}}\) = 2.5 kN, diverging in the horizontal plane. The five-fold loading cycles of these models were carried out in five 40.0 kN steps until reaching 200.0 kN, equal to four times the frictional force limit, F\({}_{\text{uT2M16}}\), defined according to Relation (1). During each test, strain gauge measuring point readings on the surfaces of the two joined angles and the inductive sensor readings of their relative displacements were recorded (Figure 6). The results of these trials were the averaged values of the aforementioned indications. (d) These tests were carried out on the same bench as that of the loading tests on the III models. The models were loaded with a vertical force, quasi-statically increasing in 20.0 kN increments until the failure effect was detected.