## 3 Parametric Study
### Results and Discussion
For this loading, the error range is the smallest, between approximately \(25\) and \(60\%\), but it is always above \(20\%\) and, therefore, the \(\pm 10\%\) regions fall outside all maps shown. 2. The comparison between the direct and iterative methods reveals a similar trend to that observed for axial force and major axis bending. Specifically, they (I) coincide for \(b/t=20+f_{yb}=200\), (II) are virtually coincident for \(b/t=20+700\) MPa and \(b/t=35+f_{yb}=200\) MPa, and (III) are similar for \(b/t=50+f_{yb}=200\) MPa. However, they are remarkably different in the two remaining cases (\(b/t=35,50+f_{yb}=700\) MPa). 3. Regarding the influence of the yield stress, the trend is similar to that observed for the major axis bending case. The yield stress has virtually no effect for \(b/t=20\), but the differences in the maps increase in the remaining cases, particularly for the direct method. Finally, Figures 12 and 13 display the error maps obtained when the numerical distortional stress is calculated using the distance from the neutral axis to the most compressed fiber, instead of the distance to the stiffener centroid. A comparison with Figures 10 and 11 shows that, for the same parameter values, the error essentially increases \(5\%\) and never exceeds \(10\%\) (this maximum corresponds to \(b/t=50\), iterative method, and \(f_{yb}=700\) MPa). Figure 6: Error isoline maps for major axis bending, direct method. Figure 7: Error isoline maps for major axis bending, iterative method. Figure 8: Error isoline maps for major axis bending, direct method, and calculations for the most compressed fiber. Figure 9: Error isoline maps for major axis bending, iterative method, and calculations for the most compressed fiber. Figure 10: Error isoline maps for minor axis bending, direct method. Figure 11: Error isoline maps for minor axis bending, iterative method. Figure 12: Error isoline maps for minor axis bending, direct method, and calculations for the most compressed fiber. Figure 4:0 Error isoline maps for minor axis bending, iterative method, and calculations for the most compressed fiber. Despite the fact that the results obtained for different loadings exhibit noteworthy differences, it is possible to draw the following general remarks for the parameter ranges considered:  
1. The errors are significantly higher for axial force, followed by major axis bending and then minor axis bending. However, for the latter, the error is never zero, being always above 25%. 2. The parameter ranges for which the error falls within \(\pm 10\%\) were identified in each map. For axial force, these regions are generally located in the lower left corner (\(h/b=1.5\), \(c/b=0.2\)), even if in some cases they extend up to the maximum \(c/b\) value considered (\(c/b=0.5\)). For major axis bending, the \(\pm 10\%\) regions are wider and located in the middle of the maps, whereas for minor axis bending they fall outside the parameter ranges considered. 3. The direct and iterative method results (I) coincide or are virtually coincident for \(b/t=20+f_{yb}=200,700\) and \(b/t=35+f_{yb}=200\) MPa, (II) are similar or very similar for \(b/t=50+f_{yb}=200\) MPa, and (III) are different or remarkably different in the two remaining cases (\(b/t=35,50+f_{yb}=700\) MPa). 4. The basic yield stress has virtually no effect for \(b/t=20\) and a rather small effect for \(b/t=35\) iterative method. For the remaining cases, the differences can be significant, particularly for the direct method. 5. The calculation of the numerical distortional stress using the distance to the most compressed fiber can lead to differences of up to 17.5% for major axis bending (for low \(h/b\) and high \(c/b\)) and 9% for minor axis bending (for all parameter ranges).