## 6 Conclusions
For soil-interacting structures with foundations (10 m \(\times\) 10 m \(\times\) 1.5 m) situated on various soil types, the SD values notably decrease as the building height increases for the ZB, ZC, and ZD soil classes (as shown in Figures 15-17). * Specifically, when the building height increases from 7 to 21 m, SD values for superstructures with a natural vibration period exceeding 2.4 s decrease by more than 20%. However, for superstructures with periods longer than 3 s, this trend does not hold when the building height increases from 14 to 21 m (as shown in Figure 18). * The decreasing trend in SA values continues as building height increases. Notably, as the building height on soft soil (ZE) rises from 14 to 21 m, the plateau region expands, contrasting with the response of buildings on hard soil (ZB), as shown in Figure 19.
* Structures built on soft soils experience larger displacements at the foundation level compared to those on hard soils. For example, when examining the displacement values at \(t\) = 2 s, as shown in Figure 20, the displacement of the foundation block on ZD soil is approximately four times greater than that on ZC soil, while the displacement on ZC soil is about three times greater than that on ZB soil. This behavior is consistently observed at other time instances. The energy absorbed by the soft soil reduces the earthquake accelerations transmitted to the superstructure, leading to less structural damage, especially in terms of life-threatening consequences. While soft soils act as natural dampers by absorbing more energy, they can cause problems such as sinking or tilting, potentially making the structure unsafe after an earthquake. The existing literature shows an increasing reliance on sophisticated models to solve SSI problems with various coupled approaches used to model the unbounded soil medium and the structure. These methods require careful attention to equilibrium and compatibility conditions at the interface between the coupled systems, often leading to a significant increase in analysis time. Additionally, the boundary conditions applied to each subdomain can affect the efficiency of coupling algorithms. In contrast, the proposed dynamic SSI system offers a more efficient approach by eliminating the need for compatibility and equilibrium linking conditions at the soil-structure interface, unlike the combined finite element (FE), boundary element (BE), and scaled boundary FE methods often used in similar studies. This study addresses SSI by assuming linear behavior for both the soil and the structure. Linear SSI analyses offer significant advantages in many engineering contexts, where nonlinear effects may not be prominent. Linear analysis serves as a valuable initial tool in design processes, offering simplified, approximate solutions that are useful in the early stages. It also helps interpret complex nonlinear behavior, as the results of nonlinear systems may sometimes align with those predicted by linear models. The procedure outlined in this study can serve as a foundation for future research, which will help address its current limitations. The authors confirm their contributions to the paper as follows: study conception and design: G.T. ; analysis and interpretation of the results: G.T. and S.G.; manuscript preparation: G.T. and S.G. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy. The authors declare no conflicts of interest.