## 5 Discussion  
### Prototype Stiffened Plates Considering a Relatively Large Web Height  
In various collision scenarios, the stiffened plates are subjected to vertical impact loads, resulting in in-plane loads borne by the stiffened web. Although the case study highlights the suitability of the proposed similarity procedure for designing distorted models with commonly suggested stiffeners in shipbuilding, it is important to consider that extreme structures with heights significantly greater than the recommended values may exist, rendering them susceptible to buckling. In this study, a straightforward similarity procedure was introduced, primarily focusing on the plastic bending moment and membrane actions, while disregarding the intricate buckling phenomena exhibited by stiffeners during impact events. However, it is crucial to acknowledge that these complex buckling behaviors have a substantial influence on the resistance force and can result in unacceptable deviations when designing distorted scaled models. Therefore, in this section, an expanded criterion is proposed to address prototypes with significantly greater heights, although they may be rare, as they can occur in practical scenarios. Accordingly, an extreme reference model (RP-6) with a web height of 60 mm, which is much larger than the suggested structures, is designed. The detailed dimensions and geometric properties are listed in Table 14 and illustrated in Figure 19.  
Additionally, the normalized sectional bending moment component M1 and axial force component F2 are collected from the numerical results, where the fully plastic moment and fully plastic force are 1,547,010 N-mm and 86,313 N, respectively, calculated based on Equations (6) and (7). Figure 20 illustrates the time-series curves, including the dynamic responses and normalized sectional moment and force results. The acceleration responses of RP-6 (red solid curve) initially exhibited a first wave crest at t1 = 0.000875 s, followed by a second wave crest at t2 = 0.010625 s, resulting from secondary buckling, and then a peak. Figure 18: Acceleration and displacement time history curves. (**a**) Acceleration; (**b**) displacement. Figure 21 and 22 present the deformation of the center and two adjacent integrated stiffeners under the impact block seen from the cut-out section at the midspan of the stiffener, in accordance with the view direction depicted in Figure 19. An obvious buckling behavior of the stiffener web can be observed in Figure 21, corresponding to the first wave crest. As the deformation progressed to a more significant stage, the stiffened plates began to resist, primarily through the application of membrane force. The second wave crest of RP-6 in Figure 20 appeared at t2 = 0.010625 s. During this stage, the stiffener web experienced heavy buckling, leading to a secondary buckle influencing not only the center stiffener but also the adjacent stiffeners, as shown in Figure 22. This behavior may contribute to a decrease in the structural rigidity, thereby influencing the occurrence of the second crest in the RP-6 results. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**No.** & **Dimensions** & **Unit** & **RP-6** \\ \hline Specim & Attached plate thickness & mm & 640 \(\times\) 340 \\  & Attached plate thickness & mm & 1.3 \\  & Stiffener dimensions & mm & \(\frac{60\times 1.15}{15\times 1.50}\) \\  & Sectional area & mm\({}^{2}\) & 195.5 \\  & Static moment & mm\({}^{3}\) & 3504.0 \\  & (\(M_{S}\))\({}_{m}\) & t & 0.00393 \\ \hline Load Case & \(R_{I}\) & mm & 80 \\  & \(M_{I}\) & t & 0.4000 \\  & (\(v_{0}\))\({}_{m}\) & m/s & 3.0 \\ \hline Results & Plastic displacement & mm & 38.50 \\  & Peak acceleration & mm/s\({}^{2}\) & 191,824 \\ \hline \hline \end{tabular}
\end{table} 
Table 14: Relevant geometrical parameters and results (RP-6). Figure 19: Schematic of RP-6 system (unit: mm). Figure 20: Time-series curves of distorted model and reference model (RP-6).