## 5 Concrete Sampling and Relation to the FE Material Model  
In [PERSON] et al. [21] it was demonstrated that the concrete material properties at the moment of release are important for the outcome of the finite element models. Therefore, additional attention is paid to these properties during the full-scale experimental test. Several concrete compressive and tensile tests were carried out. For this purpose, a total of 12 cubes of \(150\times 150\times 150\) mm\({}^{3}\) were cast. Three test specimens were preserved in the area next to the girder, whereas the other test specimens were stored under water at a temperature of 20 \({}^{\circ}\)C.  
Six compressive tests were carried out at 7 days, three at 14 days and three tests at 28 days. For each series of cubes, an average is calculated (f\({}_{\rm{cubm}}\)), and the concrete compressive cylinder strength (f\({}_{\rm{cm}}\)) is calculated as f\({}_{\rm{cm}}\) = 0.79 f\({}_{\rm{cubm}}\)[14] The results of these compression tests are summarized in Table 2. In the FE material model, the grey colored values will be used. This because, the compressive strength at time of the release (7 days) determined on cubes preserved next to the girder seems to be the most reliable value. In addition, a second material model is developed where the value obtained from the cube tests at 28 days is used, as is done most frequently in practice. Figure 8: DEMEC points attached to the test girder. Figure 9: General view of the test setup prior to strand release. Furthermore, the flexural and splitting tensile strengths are measured on several test specimens. The flexural tests are conducted according to EN12390-5 [23] and for the tensile splitting tests the EN12390-6 standard is used [24]. Fourteen prisms of 150 mm \(\times\) 150 mm \(\times\) 600 mm are cast, of which eight were tested at the time of release (7 days), three at 14 days and three at 28 days. The flexural strength is measured by conducting a three-point bending test. From this test, the flexural strength [N/mm\({}^{2}\)] can then be calculated from:  
\[f_{ct,fl}=\frac{3}{2}\frac{F_{max}l}{bh^{2}} \tag{1}\]  
with \(F_{max}\) the maximum load (N), \(l\) the distance between the hinge supports (mm), \(b\) the width of the prism [mm] and \(h\) the height of the prism (mm). According to EN 1992-1-1 [25] the relation between the flexural tensile strength from a three point bending test and the axial tensile strength can be written as:  
\[f_{ct}=0.6f_{ct,fl} \tag{2}\]  
Subsequently, the two remaining halves of the prism were used to perform the tensile splitting tests according to EN12390-6 [24]. The splitting strength of a prismatic specimen can be calculated using the formula:  
\[f_{ct,sp}=\frac{2}{\pi}\frac{F_{max}}{d\,l} \tag{3}\]  
with \(F_{max}\) the maximum load (N) and \(d\) and \(l\) the dimensions of the fracture cross-section (mm). The axial tensile strength can then be calculated by using EN 1992-1-1 (2005):  
\[f_{ct}=0.9f_{ct,sp} \tag{4}\]  
On overview of the test results and the converted values for the axial tensile strength are shown in Table 3. \begin{table}
\begin{tabular}{c c c c c} \hline
**Age [days]** & **Condition** & **f\({}_{\text{ccub}}\) [N/mm\({}^{2}\)]** & **f\({}_{\text{ccubm}}\) [N/mm\({}^{2}\)]** & **f\({}_{\text{cm}}\) [N/mm\({}^{2}\)]** \\ \hline \multirow{4}{*}{7} & \multirow{4}{*}{next to girder (outside)} & 61.5 & \multirow{4}{*}{62.6} & \multirow{4}{*}{49.5} \\  & & 61.8 & & \\  & & 64.5 & & \\ \cline{1-1} \cline{3-5}  & \multirow{2}{*}{under water (lab)} & 63.5 & \multirow{2}{*}{61.6} & \multirow{2}{*}{48.7} \\  & & 64.6 & & \\  & & 56.7 & & \\ \hline \multirow{2}{*}{14} & \multirow{2}{*}{under water (lab)} & 71.1 & \multirow{2}{*}{70.1} & \multirow{2}{*}{55.4} \\  & & 68.8 & & \\  & & 70.4 & & \\ \hline \multirow{2}{*}{28} & \multirow{2}{*}{under water (lab)} & 67.1 & \multirow{2}{*}{68.5} & \multirow{2}{*}{54.1} \\  & & 69.2 & & \\ \cline{1-1} \cline{3-5}  & & 69.1 & & \\ \hline \end{tabular}
\end{table}