## 4 Analysis Results
### Failure of Deck Substrate at Discontinuous Dimension in Section (FSD)  
Where the thicknesses of horizontal (top and bottom) plates change or the web and horizontal plate are joined together, the amount of fibers changes. These geometric (thickness change) and material (fiber amount change) discontinuities in the section cause stress concentration in the deck substrate due to local flexure under weak-axis bending [11]. Geometric discontinuity is considered in the FE model, but the material discontinuity is not fully considered because the coupon test results are not sufficient. For more precise analyses, coupon tests should be performed for all parts with different thicknesses or fiber layers. The tensile and compressive stress in the deck substrate are calculated to check for safety against FSD. Figure 23 shows the contours of the compressive and tensile stresses of the deck substrate near the loading area under LC1 and FX in ULS. The stresses concentrate where dimensions change discontinuously in the section, such as in the stepped lap joint in the flange and the corner between the flange and the web. Tables 15 and 16 summarize the maximum values of these compressive and tensile stresses. At the stepped lap joint in the flange, the maximum compressive and tensile stresses slightly exceed the design strength of the deck substrate in ULS (bold numbers in Table 15). At the corner between the flange and the web, the maximum compressive and tensile stresses are considerably greater than the design strength of the deck substrate in ULS (bold numbers in Table 16). The design strengths of the flange and web are determined, as shown in Table 10, based on the test strengths [1,3] and the partial safety factor (Table 5). The minimum of the design strengths for the flange and the web is taken as the corner design strength. To prevent this failure, more fibers should be provided at these locations to increase the compressive and tensile design strengths. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Description**} & \multicolumn{6}{c}{**Maximum Stress (MPa)**} & \multicolumn{2}{c}{**Design Strength**} \\ \cline{3-10} \multicolumn{2}{c}{} & & **Path 1** & **Path 2** & **Path 3** & **Path 4** & **Path 5** & **(MPa)** & **F.S.** \\ \hline \multirow{4}{*}{\begin{tabular}{c} Serviceability \\ limit state \\ (SLS) \\ \end{tabular} } & LC1 & \begin{tabular}{c} FX \\ \end{tabular} & 2.18 & 2.31 & 2.58 & 2.89 & 3.07 & 4.19 & 1.36 \\ \cline{2-10}  & & SS & 2.20 & 2.33 & 2.60 & 2.92 & 3.09 & 4.19 & 1.36 \\ \cline{2-10}  & & FX & 1.66 & 1.73 & 1.90 & 2.12 & 2.26 & 4.19 & 1.85 \\ \cline{2-10}  & & SS & 1.65 & 1.73 & 1.89 & 2.11 & 2.25 & 4.19 & 1.86 \\ \hline \multirow{4}{*}{\
\begin{tabular}{c} Ultimate limit \\ state (ULS) \\ \end{tabular} } & LC1 &
\begin{tabular}{c} FX \\ \end{tabular} & 3.93 & 4.16 & 4.65 & 5.22 & **5.53** & 4.19 & 0.76 \\ \cline{2-10}  & & SS & 3.97 & 4.20 & 4.69 & 5.26 & **5.58** & 4.19 & 0.75 \\ \cline{2-10}  & & FX & 2.97 & 3.11 & 3.40 & 3.80 & 4.05 & 4.19 & 1.03 \\ \cline{2-10}  & & SS & 2.96 & 3.09 & 3.38 & 3.79 & 4.04 & 4.19 & 1.04 \\ \hline \hline \end{tabular}
\end{table} 
Table 14: Maximum shear stresses in adhesive between bonded flanges. Figure 22: Shear stress of adhesive between flanges under LC2 in ULS.