## 4 Results and Discussion
### Floor Response Spectra (FRSs)  
This section and the results presented here are based on past research [72], and they have been reproduced here to enhance readability and facilitate comprehension for the readers. The considered NSCs are elastic single degree of freedom (SDOF) systems with masses much smaller than the supporting structure. They have a single attachment point to the floor, and the dynamic interaction effects with the structure can be disregarded. The FRS technique decouples and independently assesses NSCs and structure in a predefined manner. For NSCs to create the appropriate FRSs, absolute acceleration data are collected from each floor's model separately. The floor response spectra for each of the models taken into consideration were derived in the manner that was previously indicated. For each ground motion, the acceleration response is recorded at multiple floor levels to obtain FRSs. The mean findings are displayed for each floor and were achieved at a damping ratio of 5%. Figures 7 and 8 display the relationship between the vibration period of a non-structural component (\(T_{s}\) in seconds) and the peak spectral acceleration (\(S_{a}\) in \(g\)) of the floor. When the FRS is plotted throughout a wide variety of periods, maximum spectrum peaks should appear at the fundamental natural period of the supporting structure [73]. FRS peaks align with the typical periods of relevant building models. In all considered models, spectral accelerations are higher in the X direction for the first modal period. Increasing the soft-story height (from 5 m to 7 m) decreases FRS amplitudes across all floor levels. In all the models, the FRS intensity decreases from the upper fifth story to the lower first level. The soft story's presence and location have a notable impact on the FRS, as evident from the FRS curves depicted in Figures 7 and 8. In a M**S**ref**, the FRS exhibits two peaks corresponding to the first and second modal periods for the first and second floor levels. The impact of the higher mode is negligible for the higher floors (third, fourth, and fifth). This observation aligns with previous research findings [16]. Peak spectral acceleration related to the higher modes increases with increasing building height (ten-story reference building). Up to the third floor, the second and thirds modes significantly influence the peaks of FRSs, whereas the higher mode's contribution has less of an impact as the floor levels increase. This observation confirms the findings of [PERSON] and [PERSON] [19]. Consequently, it can be deduced that, in the absence of vertical stiffness irregularities, short-period NSCs located in the lower floors of a building would experience significant earthquake forces. A noticeable amplification of spectral accelerations between floors can be observed with a 5m soft story. The spectra of the levels begin to converge as the height of a soft story increases to 7m. In model M**S**bs**, the peak spectral acceleration at the first modal period of the bottom level (first floor) experiences significant increases of 79% in the X direction and 55.3% in the Y direction. Corresponding to this, in M**10**bs**, the \(S_{a}\), associated with the second modal period, is amplified by 67.9% and 48.6% in the X and Y directions, respectively, when compared to M**10**ref**. As compared to M**S**ref**, the model M**S**bs**? 's spectral acceleration increased by 71.6% and 33%, respectively, in both the X and Y directions. The \(S_{a}\) of the top floor for the first modal period is higher in both the directions of excitation in model M**S**bs**? compared to M**S**ref**. It increases by 6.36% and 0.55%, respectively. In the M**10**bs**? configuration, the \(S_{a}\) for the second modal period increases by 23.28% in the X direction and 49.8% in the Y direction compared to the M**10**ref** configuration. In the M**S**bs**? model, the spectral acceleration increases by 2.72% in the X direction and 0.37% in the Y direction compared to M**S**ref**.