## 4 Results and Analysis
### Effect of Transverse Bulkheads on Overall Bend Strength  
To analyze the effect of the transverse bulkhead position on the overall bend strength of SHGs, the overall response results of eight different SHGs under the same load in cases 1-8 are analyzed below. Figure 12 shows the contours of different SHGs at various times. The arrows indicate the direction of motion, and the symbols on the curves indicate the position of transverse bulkheads. At an early stage of the explosion, the middle of the SHGs rapidly displaces under the combined action of a spherical shock wave and bubble expansion boundary. Moreover, the displacement of both ends is relatively slow due to the inertial effect, so the overall structure presents hogging bend deformation, as shown in Figure 12a. In Figure 12b, the main action time of the shock wave has passed. Under the influence of material resilience, the overall deformation gradually enters the unloading stage, and the bend amplitudes decrease to varying degrees. At this moment, the deflection amplitude of all structures is within 0.0025 m, and the ratio to the total length is 1.67%, so the SHGs can be consiIn summary, the response behavior and damage degree of SHGs with different transverse bulkhead configurations are significantly different under the same load. This shows that transverse bulkheads can contribute important longitudinal strength when facing a near-field underwater explosion load, and the effect of transverse bulkheads differs at different positions. When predicting the overall damage behavior of the structure, attention should be paid to the longitudinal position parameters of different transverse bulkheads. The dimensionless deflection \(w^{*}=w/L\) is introduced as a parameter to characterize the relative bend degree of SHGs. Figure 13 shows the dimensionless deflection time-history curves of each structure. For these SHGs, if the transverse bulkhead is at the boundary of the predicted bend zone, the corresponding structure number is SHG(0.162). As seen from Figure 13, there are great differences between the deflection of SHGs with transverse bulkhead position parameters greater than 0.162, indicating that the transverse bulkhead outside the bend zone greatly influences the overall damage. In addition, SHGs with different transverse bulkhead configurations show little difference in hogging behavior but a great difference in sagging behavior. This is because, when bent downward, the upper part of the side plate is compressed, and the lower part is stretched. The bend requires yielding and folding in the upper part to make space. Similarly, in the hogging bend, the lower part of the side plates will appear more yielding and folding. For the SHG structure without the deck used in this paper, the lower part of the side plates is orthogonally connected with the bottom plate to form a strong constraint, which is more difficult to yield than the upper part. Figure 12: Contours of simplified hull girders: (**a**) 5 ms, (**b**) 12 ms, (**c**) 18 ms, (**d**) 30 ms, (**e**) 45 ms, (**f**) 55 ms.  
Further, the maximum sagging amplitudes of each structure are given as statistics in Figure 14. For the SHGs with transverse bulkheads, the response changes from whipping motion to sagging damage as the \(x^{*}\) increases. With the change in position, the restraining ability of the transverse bulkhead to sagging amplitude is shown to have a three-stage pattern, from strong to weak. The transverse bulkhead in the bend zone can significantly reduce the overall bend amplitude. The transverse bulkhead located outside the bend zone also has a non-negligible effect. For example, SHG(0.8) has a 94.5% change in deflection relative to SHG(1) without transverse bulkheads. The sagging deflection of SHG(1) without a transverse bulkhead is between SHG(0.2) and SHG(0.33) and is not the maximum. This indicates that the transverse bulkhead does not always play a positive role in the bearing near-field explosion bubble load.