## 5 Results
### Ground Surface Acceleration Values and Soil Amplification
When all the used acceleration records were examined, it was determined that the accelerations  
Figure 14: The spectral amplification values calculated for two scaled accelerations. Figure 15: AMP of two different earthquakes at T = 0.01 (**a**), 0.1 (**b**), and 1.0 s (**c**). comparison of values. Analyses with these parameters better represent the region. In addition, the scaling of earthquake acceleration records to be used in the analysis is an important factor for soil amplification analysis. For this purpose, soil dynamic parameters were determined by dynamic triaxial and resonant column tests using undisturbed samples within the borders of Sakarya province, which is located on the NAFZ in Turkey, one of the major earthquake zones of Europe. Then, 11 earthquake acceleration records reflecting the seismicity characteristics of the region were selected and scaled with two different scaling methods from the literature. As a result of the nonlinear analysis, soil amplification factors and spectral acceleration values were obtained. There are numerous studies in the literature on site-specific analysis, most of which focus on regional investigations. [PERSON] [29] conducted a one-dimensional soil amplification analysis and represented the region using GIS mapping. Unlike our study, soil dynamic parameters in [PERSON]'s research were determined and introduced into the program through built-in functions rather than experimental methods. When comparing the results, both studies indicate that the regulation is insufficient in representing certain points. [PERSON] et al. [46] performed a soil amplification analysis in Konya province and evaluated the results based on TEC 2018. Their study was conducted on a regional scale according to soil types, with soil dynamic parameters obtained through program-based models. The experimental approach in our study differs from theirs. However, when comparing the results, both studies reveal that TEC 2018 is not sufficiently representative at high-period values. [PERSON] et al. [47] conducted one- and two-dimensional analyses in Izmir province, incorporating both field observations and numerical modeling. Their study highlighted the weak points of the regulation and examined the basin effect. When comparing the experimental and analytical aspects of our study, a key difference is that their research did not include experimental soil dynamic parameter calculations, focusing solely on numerical analysis. Nevertheless, both studies conclude that the soil amplification effect in the regulation is not adequately represented. Previous studies on soil amplification analysis have generally relied on shear modulus and damping curves obtained from reference curves suggested by software programs. However, in this study, these curves were derived through site-specific experimental research. Additionally, when evaluating the performance of TEC 2018 in light of recent studies, a common issue emerges: the regulation fails to sufficiently capture soil amplification effects, particularly at high periods. The analysis results were first compared with the spectral envelope proposed by TEC 2018 for the region, and it was examined how well it represents the spectral acceleration values. Here, it can be said that the results obtained from the two different scaling methods are not fully representative. In the Sc-1 method, it was determined that the spectrum envelope was low at high-period values of the peak region in each borehole analysis. In the Sc-2 method, it was determined that the peak was insufficient only in the B1 borehole and reached very high values in other borehole analyses. This discrepancy is due to the fact that the regulation recommends a spectrum envelope based on more general data. However, the general recommendation of such an important parameter in structural design significantly affects structural analysis and structural element sizing.