## 4 Results and Discussion
### Peak Floor Acceleration (PFA)  
Soft-story building models have higher floor acceleration amplification at both the bottom and top soft-story levels in orthogonal directions compared to the reference building models. In the X direction, for example, the ratio of \(\mathit{PFA}/\mathit{PGA}\) increases by 39.7% and 26.1% for the bottom floor of model M\({}_{\text{5 bs}}\) with soft-story heights of 5 m and 7 m, respectively, compared to model M\({}_{\text{5 ref}}\). Similarly, the top floor of M\({}_{\text{5 bs}}\) shows a raise of 9.1% and 7.2% in the ratio of PFA/PGA for soft-story heights of 5 m and 7 m, respectively, compared to M\({}_{\text{5 ref}}\). For M\({}_{\text{10 bs}}\), the ratio of \(\mathit{PFA}/\mathit{PGA}\) in the bottom floor increases by 62.6% and 85.5% for soft-story heights of 5 m and 7 m, respectively, in the X direction, compared to model M\({}_{\text{10 ref}}\). Additionally, the top floor of M\({}_{\text{10 bs}}\) experiences increases of 22.2% and 24.1% in the ratio of PFA/PGA for soft-story heights of 5 m and 7 m, respectively, in the X direction, compared to M\({}_{\text{10 ref}}\).  
In the middle soft-story building model, floors below the soft-story level show higher floor acceleration amplification compared to the reference building models. For example, in the five-story middle soft-story building, the second-floor experiences increase of 14% and 11.8% in the ratio of \(\mathit{PFA}/\mathit{PGA}\) for soft-story heights of 5 m and 7 m, respectively, in the X direction, compared to the reference building. Similarly, in the ten-story building model, the fifth-floor shows increases of 22.8% and 54.2% in the ratio of \(\mathit{PFA}/\mathit{PGA}\) for soft-story heights of 5 m and 7 m, respectively, in the X direction, compared to the reference building. This indicates that the location of a soft story significantly influences peak floor accelerations.  
Different seismic codes, such as ASCE 7-16 [33] and Eurocode 8 [71], offer formulas to evaluate the variations in peak floor acceleration concerning the building's height. The floor amplification factor (\(\mathit{PFA}/\mathit{PGA}\)) is determined using Equations (1) and (2) for these codes.  
\[\mathit{PFA}/\mathit{PGA}= 1+2\frac{z}{h} \tag{1}\]  
\[\mathit{PFA}/\mathit{PGA}= 1+1.5\frac{z}{h} \tag{2}\]  
Figure 6 reveals that the code formulations suggest a linear relationship between the floor amplification and the building height. However, the analysis shows that floor acceleration varies nonlinearly throughout the building height. Additionally, the code formulations underestimate the floor acceleration demands at soft-story levels in all building models considered. This suggests that the linear hypothesis in the code-based formulas may lead to the underestimation or overestimation of floor acceleration demands. To improve accuracy, the current code-based formulas could be modified to consider the effects of vertical stiffness irregularity, which influences floor acceleration demands. In summary, the code-based formulations do not adequately predict the peak responses of non-structural components with respect to building height.  
Figure 6: Comparison of floor amplification factors between the considered building models and current codes [33; 71].