## 4 Results and Discussions
However, as the L/D ratio increases to 6, 8, and 10, the 1D model with FE-extracted p-y curves converges more closely to the FE results. This indicates a reduction in the contribution of other resisting components. At an L/D ratio of 10, the results from the 1D DNV p-y, FE, and 1D model with FE-extracted p-y curves are quite similar, indicating minimal diameter effects for slender monopiles. This demonstrates that for slender piles  
Figure 13: Pile head displacement with increasing length for the 8 m monopile based on the results of FEM and 1D DNV p–y method. with an L/D ratio of 10 or higher, the 1D DNV method can predict pile behavior with reasonable accuracy. Figure 14: Comparison between the FE, 1D DNV p–y, and FE p–y curves for the mudline-load–displacement response of the D8 monopile at L/D ratios of (**a,b**) 4, (**c,d**) 6, (**e,f**) 8, and (**g,h**) 10. To evaluate the impact of the pile slenderness ratio (L/D) on the relative contribution of the four resisting components, the contribution of each component was expressed as a percentage of the applied moment around the center of rotation (which equals the restoring moment exerted by the soil on the pile). The total moment contribution from the p-y and base shear components (i.e., force components) was determined by multiplying the component force at each depth interval by its distance from the center of rotation (the point of zero lateral displacements, calculated during each load step) and summing these moments for each component. The contribution from the distributed moment caused by vertical shaft shear forces was calculated by integrating the distributed moment, m, along the length of the pile shaft. The total moment from each soil reaction component was then divided by the externally applied moment (applied lateral force \(\times\) vertical distance to the point of rotation) to calculate the \"moment contribution ratio\" (MCR). The maximum displacement of 0.2D has been exerted on the monopile, and the displacement of the graphs presented in Figure 15 has been normalized by the diameter of the monopile (D). The MCR values for each soil reaction component at slenderness ratios of 4, 6, 8, and 10 are presented in Figure 15 for the 8 m monopile. The results indicate that the primary portion of the resisting moment across all slenderness ratios is provided by the distributed lateral load acting along the monopile shaft (\(MCR_{p-y}\)). Furthermore, the contribution of this component increases as the slenderness ratio increases. Specifically, the contribution  
Figure 15: Moment contribution ratio diagrams for the 8 m monopile with L/D ratios of (**a**) 4, (**b**) 6, (**c**) 8, and (**d**) 10.  
rises from approximately 87% at an L/D ratio of 4 (Figure 15a) to about 96% at an L/D ratio of 10 (Figure 15d). Conversely, the combined contribution of other components--shear force at the pile base (\(MCR_{BS}\)), vertical shear stresses acting on the pile shaft (\(MCR_{M-\Theta}\)), and base moment (\(MCR_{BM}\))--decreases as the slenderness ratio increases. At an L/D ratio of 4, these components contribute around 13% (Figure 15a), but their combined contribution drops to 4% at an L/D ratio of 10 (Figure 15d). The results also revealed that the base moment \(MCR_{BM}\) minimally contributed to the moment resistance of the monopile with a contribution of around 3 percent at an L/D ratio of 4 and almost zero at an L/D ratio of 10. Except for the L/D ratio of 4 where the vertical shear stresses along the pile shaft, \(MCR_{M-\Theta}\) have a relatively greater contribution, in other L/D ratios, the \(MCR_{M-\Theta}\) and \(MCR_{BS}\) have similar contributions.