## 4 Results and Discussion
### Calculation of the Normalized Edge Displacement Using Dynamic and Static Analysis
Figure 5: Normalized flexible edge displacement (with \(b/r=1.1\), \(Ty<1\) s): (**a**) Static edge displacement; (**b**) Dynamic edge displacement; (**c**) Static vs. dynamic edge displacement. Figure 6: Normalized flexible edge displacement (with \(b/r=1.1\), \(1<Ty<2\) s): (**a**) Static edge displacement; (**b**) Dynamic edge displacement; (**c**) Static vs. dynamic edge displacement. Figure 7: Normalized flexible edge displacement (with \(b/\!\!\!r=1.1\), \(Ty\!\!\!>2\) s): (**a**) Static edge displacement; (**b**) Dynamic edge displacement; (**c**) Static vs. dynamic edge displacement. Figure 8: Normalized flexible edge displacement (with \(b\)/\(r\) = 1.4, \(Ty\) \(<\) 1 s): (**a**) Static edge displacement; (**b**) Dynamic edge displacement; (**c**) Static vs. dynamic edge displacement. Figure 9: Normalized flexible edge displacement (with \(b/r=1.4\), \(1<Ty<2\) s): (**a**) Static edge displacement; (**b**) Dynamic edge displacement; (**c**) Static vs. dynamic edge displacement. Figure 10: Normalized flexible edge displacement (with \(b/r=1.4\), \(Ty>2\) s): (a) Static edge displacement; (b) Dynamic edge displacement; (c) Static vs. dynamic edge displacement. Figure 11: Normalized flexible edge displacement (with \(b/r=2.45\), \(Ty<1\) s): (**a**) Static edge displacement; (**b**) Dynamic edge displacement; (**c**) Static vs. dynamic edge displacement. Figure 12: Normalized flexible edge displacement (with \(b/r=2.45\), \(1<Ty<2\) s): (**a**) Static edge displacement; (**b**) Dynamic edge displacement; (**c**) Static vs. dynamic edge displacement. Figure 13: Normalized flexible edge displacement (with \(b/r=2.45\), \(7y>2\) s): (**a**) Static edge displacement; (**b**) Dynamic edge displacement; (**c**) Static vs. dynamic edge displacement. Comparing Accidental Torsion Response for Various Building Aspect Ratios using Static and Dynamic Analyses  
Static analysis produces more conservative assessment of accidental torsion compared to dynamic analysis for building systems with \(\Omega<1.0\), as shown in Figures 1-13. Moreover, for buildings with floor plan aspect ratio of 1.0, i.e., roughly square floor plan (\(b\)/\(r\) = 2.45), and having \(\Omega<<1.0\), static analysis is very conservative compared to dynamic analysis. Further examination of the response quantity \(\hat{u}_{b/2}\) for structures with \(\Omega\) = 1.0, indicates that buildings that are square in plan geometry (\(b\)/\(r\) = 2.45) are less susceptible to accidental torsion than buildings that are more rectangular in plan. Regardless of the fundamental period, the normalized edge displacement, \(\hat{u}_{b/2}\), for building with \(\Omega\) = 1.0 are less in buildings with square geometry as shown in Figure 11, Figure 12, and Figure 13c, compared to buildings that are rectangular in plan (Figures 5c, 6c, 7c, 8c, 9c and 10c). The Drop in Accidental Torsion Response Obtained through Dynamic Analysis of Buildings with Uncoupled Frequency Ratio \(\Omega\) = 1  
Dynamic analysis in the previous sections of this article demonstrated that a consistent drop in accidental torsion response decreases as uncoupled frequency ratio approaches \(\Omega\) = 1. It is worthy however to note that the accidental torsion response based on dynamic analysis, within the range of \(\Omega\) values covered in this study, is characterized by a curve of consisting of two peaks and some valleys. It is important to shed more light on the structural stiffness circumstances that would lead to the drop in accidental torsion response of building structures having uncoupled torsional frequency \(\Omega\) = 1 when dynamic analysis is used. To this end, accidental torsion evaluation method stipulated in Eurocode 8 (EC 8) is presented and discussed. To this end, in next paragraphs we discuss the concepts of floor plan irregularity, torsional behavior, and torsional radius in Eurocode 8 (EC 8). Similar to other codes, EC 8 requires that building floor plans should be classified as regular or non-regular for the purpose of seismic deigns.