## 4 Numerical Results
### One-Way FSI Analysis
#### 4.3.2 Transient Structural Analysis  
This section examines the one-way FSI analysis, which applied the pressure calculated by the sloshing analysis to the FEM model under seismic loads.  
Figures 16 and 17 compare the total deformation and von Mises stress, respectively, for the components of the water tank in the one-way FSI analysis. CASE I-3 represents the final step of the quasi-static analysis, whereas CASE II and CASE III show the structural response at the times of maximum total deformation and von Mises stress. Table 6 summarises the maximum values of the total deformation and von Mises stress over the entire analysis.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Case** & **Item** & **PDF Panel** & **Steel Beam Frame** \\ \hline \multirow{4}{*}{\begin{tabular}{c} CASE III-1 \\ (1-way FSI, \\ No Plate) \\ \end{tabular} } & Total Deformation (mm) & 14.971 & 7.268 \\  & von Mises Stress (MPa) & 8.810 & 228.780 \\  & \begin{tabular}{c} Shear Stress \\ (MPa) \\ \end{tabular} & \begin{tabular}{c} XY-Plane \\ YZ-Plane \\ YZ-Plane \\ YZ-Plane \\ ZX-Plane \\ \end{tabular} & - & 50.049 \\  & \begin{tabular}{c} Total Deformation (mm) \\ \end{tabular} & \begin{tabular}{c} - \\ 12.481 \\ 7.556 \\ \end{tabular} & \begin{tabular}{c} 83.310 \\ 183.040 \\ 36.514 \\ \end{tabular} \\  & \begin{tabular}{c} Shear Stress \\ (MPa) \\ \end{tabular} & \begin{tabular}{c} XY-Plane \\ YZ-Plane \\ YZ-Plane \\ ZX-Plane \\ \end{tabular} & - & 62.819 \\ \hline \multirow{4}{*}{\begin{tabular}{c} CASE III-3 \\ (1-way FSI, \\ 70\%H) \\ \end{tabular} } & Total Deformation (mm) & 12.479 & 5.367 \\  & \begin{tabular}{c} von Mises Stress (MPa) \\ \end{tabular} & \begin{tabular}{c} 9.462 \\ - \\ 7.556 \\ \end{tabular} & \begin{tabular}{c} 179.140 \\ 183.040 \\ 36.514 \\ \end{tabular} \\  & \begin{tabular}{c} Total Deformation (mm) \\ \end{tabular} & \
\begin{tabular}{c} 12.479 \\ 9.462 \\ - \\ \end{tabular} &
\begin{tabular}{c} 5.367 \\ 179.140 \\ 38.640 \\ 67.177 \\ 59.614 \\ \end{tabular} \\ \hline \end{tabular}
\end{table}
Table 6: Comparison of structural response in quasi-static, transient, and one-way FSI analysis.  
Figure 15: Comparison of forces acting on the tank wall amongst CASE III-1, -2, and -3.  
greater maximum level of both total deformation and von Mises stress than CASE II, as shown in Figure 13. This indicates that fluid interactions are essential for determining high-accuracy structural responses under seismic loads.  
Comparing CASEs III-1, -2, and -3 shows that the anti-wave plate clearly decreased the structural responses in the PDF panel. In particular, the total deformation at the bottom of the PDF panel was decreased as the size of the anti-wave plate increased. However, the maximum von Mises stress occurred near the connection between the bottom of the PDF panel and the anti-wave plate, as shown in Figure 17b. Therefore, while the anti-wave plate mitigated structural responses, a systematic design process is needed to prevent a significant increase in stress at the connection.  
Figure 17 shows the contour of structural responses for the steel beam frame in the one-way FSI analysis. The structural responses decreased from CASE III-1 to CASEs III-2 to CASE III-3, due to the anti-wave plate increasingly mitigating the free surface motion.