## 4 Methods
### Numerical Modelling
#### 4.2.3 Full-Size Sandwich Element Model
The performance of the anchors was experimentally investigated according to that given in Section 4.1.1 and the design shear load capacities of the upper (\(H_{\text{Rup,d}}\), \(H_{\text{Run,d}}\)) and lower (\(H_{\text{Rlup,d}}\), \(H_{\text{Rlup,d}}\)) anchors summarized in Table 4 in Section 5.1. \[ \begin{split}\text{If }H_{\text{Eu,d}}\;>\;0\;\text{then }H_{\text{Eu,d}}\;\leq\;H_{\text{Rup,d}}\;\text{otherwise }\left|H_{\text{Eu,d}}\right|\;\leq\;H_{\text{Run,d}}\\ \text{and}\\ \text{If }H_{\text{El,d}}\;>\;0\;\text{then }H_{\text{El,d}}\;\leq\;H_{\text{Rlup,d}}\;\text{ otherwise }\left|H_{\text{El,d}}\right|\;\leq\;H_{\text{Rlup,d}}\end{split}  \tag{3}\]  
Verification at the SLS, representing a lower load level, usually relates to appearance, functioning and comfort of occupants, e.g., deflections and cracking. According to EN 1992-1-1 [33], the extent of cracking shall be limited in order to ensure the adequate functionality or durability of the structure, as well as to safeguard an aesthetically pleasing surface. The requirements of maximum crack width are normally only valid for steel reinforced concrete structures. When carbon textile reinforcement is used, corrosion is not a concerning issue because the grids are designed to be highly durable. By comparing between different codes given in fib bulletin 40 [34], the crack width limits are less restricted for FRP reinforced concrete. However, the knowledge is rather scarce, and it is stated that in absence of information the limitations for steel reinforced concrete could be adopted also for FRP \begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**Load Case**} & \multicolumn{3}{c}{**SLS**} & \multicolumn{3}{c}{**ULS**} \\ \cline{2-7}  & \(W_{\text{ext}}\) [Pa] & \(W_{\text{int}}\) [Pa] & \(W_{\text{SLS}}\) [Pa] & \(W_{\text{ext}}\) [Pa] & \(W_{\text{int}}\) [Pa] & \(W_{\text{ULS}}\) [Pa] \\ \hline _LC1_ & 514 & 192 & 706 & 771 & 288 & 1059 \\ \hline _LC2_ & \(-\)771 & \(-\)128 & \(-\)899 & \(-\)1157 & \(-\)192 & \(-\)1349 \\ \hline _LC3_ & \(-\)771 & 192 & \(-\)579 & \(-\)1157 & 288 & \(-\)869 \\ \hline \end{tabular}
\end{table} 
Table 3: Three wind load cases applied to sandwich element. reinforced concrete. For the lowest exposure classes given in [33], the crack width has no influence on durability and the given crack width limit of 0.4 mm is just set to guarantee acceptable appearance. However, crack widths can also be controlled to satisfy specific aesthetic requirements. As stated in ACI 533R-11 [35], the aesthetic effect of a crack in a facing is correlated to the surface's texture. For smooth surfaces, e.g., cast-in-place concrete, and coarse textured surfaces, e.g., exposed aggregate concrete, crack widths limited by structural demands are considered aesthetic. Concerning high quality smooth surfaces, it is recommended that cracking be limited to 0.13 mm for interior facings. According to [33], the function or appearance of a member or structure should not be negatively impacted by deformation. In general, the limit of the design deflection is specified to either \(L\)/250 or \(L\)/500, where \(L\) is the effective span of the element. In [35], deflection limits are given specifically for non-load bearing precast wall elements, saying, deflection of any point on the facing measured from its original position should not exceed \(L\)/480. For the element in this study, the more restrictive limit according to [33] corresponds to a maximum deflection of 2800/500 = 5.6 mm.