## 4 Results
### Experimental Analysis
#### 4.1.1 TGIB-fw
As expected, the ductility values, given by the ratio of the maximum force (F\({}_{\text{max}}\)) to the force at the first crack (F\({}_{\text{cr}}\)), were highest for silicone at 5.3, and lowest for epoxy at 1.3. The bending stiffness of the specimens are then inversely proportional to the ductility. The highest values were found for the test specimens bonded with epoxy adhesive, followed by acrylate and finally silicone. Figure 20: Diagram force vs. deflection for the annealed float glass (adhesive: S—silicone Sika Sil SG500, A—acrylate Sika Fast 5215, E—epoxy Sikadur®-31 CF Normal, AF—annealed float glass). Fully tempered glass (FT) is safer and has up to three times the bending strength of annealed float glass. Figure 21 shows the force (F) and displacement (u) diagram for TGIB-fw with FT glass. Practically all samples showed the expected linear behaviour. Only sample S_FT_03 showed a deviation from the linear behaviour. This may be mainly due to the design of the test, as in this case no steel plate was inserted between the weight yoke and the timber beam to prevent the yoke from pressing into the timber. The second reason is due to the material properties of silicone. Silicone is extremely elastic and, in this case, only the adhesive can be plasticized. No special observations were made with the acrylic specimens. In the samples bonded with epoxy adhesives, a defect occurred in sample E_FT_02. Here, collapsing of the adhesive was observed, causing the weight yoke to line the glass web and we had to stop the test. This was mainly due to the stiffness of the epoxy adhesive and the thickness of the bonded line, which was 1 mm. Therefore, the last measured force of 20.7 kN corresponds to the actual failure. In fully tempered glass no post-critical strength is observed here. The first crack corresponds to the final failure, as shown in Table 8. This value, Fmax, can be up to twice the \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline
**Material** & **F\({}_{\text{cr}}\) [kN]** & **F\({}_{\text{max}}\) [kN]** & **u\({}_{\text{cr}}\) [mm]** & **u\({}_{\text{max}}\) [mm]** & **Ductility d = u\({}_{\text{max}}\)/u\({}_{\text{cr}}\)** & **q = F\({}_{\text{max}}\)/F\({}_{\text{cr}}\)** & **EI [MNm\({}^{2}\)]** \\ \hline S\_AF\_01 & 4.6 & 15.3 & 11.8 & 54.8. & 4.7 & 3.3 & 0.714 \\ S\_AF\_02 & 4.1 & 18.2 & 9.9 & 69.1 & 7.0 & 4.4 & 0.753 \\ S\_AF\_03 & 5.3 & 15.6 & 13.0 & 59.5 & 4.6 & 2.9 & 0.746 \\
**Mean** & **4.7** & **16.4** & **11.6** & **61.1** & **5.3** & **3.6** & **0.738** \\ A\_AF\_01 & 6.1 & 18.5 & 9.6 & 41.1 & 4.3 & 3.0 & 1.155 \\ A\_AF\_02 & 5.3 & 16.5 & 7.8 & 36.9 & 4.7 & 3.1 & 1.237 \\ A\_AF\_03 & 6.2 & 17.7 & 9.9 & 40.6 & 4.1 & 2.9 & 1.138 \\
**Mean** & **5.9** & **17.6** & **9.1** & **39.5** & **4.3** & **3.0** & **1.176** \\
**value** & **12.1** & 13.1 & 21.3 & 23.7 & 1.2 & 1.1 & 1.088 \\ E\_AF\_02 & 8.9 & 11.1 & 14.2 & 18.7 & 1.4 & 1.3 & 1.230 \\ E\_AF\_03 & 10.7 & 12 & 21.6 & 27.3 & 1.4 & 1.1 & 0.971 \\
**Mean** & **10.6** & **12.1** & **19.0** & **23.2** & **1.3** & **1.2** & **1.096** \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Results of measurements for TGIB-fw with annealed float glass (AF). Figure 21: Diagram force vs. deflection for the fully tempered glass (adhesive: S—silicone Sika Sil SG500, A—acrylate Sika Fast 5215, E—epoxy Sikadur®-31 CF Normal, FT—Fully. value for the annealed float glass sample. F\({}_{\text{crack}}\) and F\({}_{\text{max}}\) are therefore the same. Therefore, the parameter \(q\) = 1.0 and the ductility \(d\) = 1.0 for all test samples and are thus not specially presented in Table 7.  
The highest load was observed in the acrylate specimens, where the average value was 26.7 kN and the highest measured value was as high as 28.8 kN. In the case of the epoxy adhesive, there is considerable variation in the maximum load values. It should be noted that the specimen E_ FT_02 * was not taken into account in the calculation of the mean values for the maximum load and displacement, since the failure occurred after the failure of the adhesive.