# Assessing the Seismic Demands on Non-Structural Components Attached to Reinforced Concrete Frames
## 5 Results and Discussion  
### Elastic FRS for Regular and Irregular Buildings  
The mean response spectra were obtained from the floor response at various floor levels of two different building models. Floor response in the 'X' direction was calculated using a time history analysis of the building models for all three soil types by utilizing the ground excitations shown in Tables 1-3. The floor response obtained for each ground motion is sent into the SDOF system, which generates the floor response spectrum. The resulting individual response spectra are then used to calculate the mean floor response spectrum. The generated FRS is associated with the 5% damping ratio. Figures 5 and 6 show the elastic FRS for the regular and irregular buildings for all three soil types. Primarily, it can be observed from both figures that the response increases from the bottom first story to the top fifth story for all types of soils. Moreover, the figures show that the various peaks in the FRS correspond to the different fundamental modes of the building models. The peaks observed in the FRS are recorded close to elastic modal periods (Table 4). This \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Mode**} & \multicolumn{2}{c}{**Regular Model**} & \multicolumn{2}{c}{**Irregular Model**} \\ \cline{2-3}  & **UX** & **UZ** & **UX** & **UZ** \\ \hline
1 st & 0.82 & 0 & 0.72 & 0 \\
2 nd & 0.93 & 0 & 0.94 & 0 \\
3 rd & 0.97 & 0 & 0.99 & 0 \\
4 th & 0.99 & 0 & 1.0 & 0 \\
5 th & 1.0 & 0.63 & 1.0 & 0.61 \\
6 th & 1.0 & 0.63 & 1.0 & 0.61 \\
7 th & 1.0 & 0.63 & 1.0 & 0.61 \\
8 th & 1.0 & 0.86 & 1.0 & 0.83 \\
9 th & 1.0 & 0.86 & 1.0 & 0.83 \\
10 th & 1.0 & 0.93 & 1.0 & 0.93 \\
11 th & 1.0 & 0.93 & 1.0 & 0.93 \\
12 th & 1.0 & 0.96 & 1.0 & 0.96 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Modal mass participation ratios of regular and irregular building models. Figure 4: Mode shapes of regular and irregular building models. In the FRS curves for the building models, the first, second, and third peak refers to the maximum response proximity to the first, second, and third modal periods, respectively. In the case of the \(M_{R}\) model (Figure 5), the first peak of spectral acceleration is the uppermost for the second, third, fourth, and fifth floor levels, whereas second and third peak floor spectral acceleration values are foremost for a lower story (first floor level). Similarly, for the \(M_{\rm IR}\) model (Figure 6), two peaks are observed where the second peak acceleration value is the foremost for two floors (first and second floor levels), whereas the first peak response value is the uppermost for the remaining floor levels (third, fourth, and fifth). From Figures 5 and 6, it can be inferred that the spectral acceleration values increase with increasing frequency. Figure 6: FRS of an irregular building for various soil types. soil flexibility. To better understand the effect of soil type on the FRS, the floor spectral acceleration of the building models with respect to the first modal period is shown in Figure 7. From the figure, the effect of soil type on the building models can be seen and is significant at higher floor levels. It can also be observed that the difference in the floor spectral acceleration between the medium and soft soil is less, whereas it is more between the hard and soft soil. The difference in the response between various soils increases with the floor level. Interestingly, under medium and soft soil, the floor spectral acceleration of a regular building rises by 32.4% and 41.3%, respectively, compared with the response under hard soil at the top level (5 th floor). Compared with hard soil, the floor spectral acceleration of an irregular building at the highest floor level (5 th floor) increases by 29.2% in medium soil and 41.5% in soft soil. Additionally, it can be shown that the irregular building exhibits an increase in floor response for hard soil of 26.1% and 10%, respectively, at the 1 st and 5 th floor levels, compared with the regular building.