## 6 Selection of the Critical Ground Motion Parameters on Seismic Response  
Based on the results of the comparison from the previous section, it can be concluded that there is a significant correlation between certain characteristics of earthquake records and the maximum interstory drift as a measure of damage. However, to make the comparison measurable, given the different units of measurement, all earthquake record characteristics, as well as interstory drift values, were normalized to a value range of 0-1. Correlation analysis was then conducted to determine the strength of influence and the degree of alignment in response to changes in the respective parameters. The correlation results for both observed seismic regions are presented in Table 9, which demonstrates that the PGV, SED, and HI characteristics have the greatest impact on the nonlinear response of the structure. This conclusion is supported by the fact that the correlations of the normalized values of these three characteristics reach approximately 90%, distinguishing them from other earthquake record characteristics.  
Based on the literature review, as it is stated in [4; 9], PGV was an efficient parameter for both low-rise and high-rise buildings designed according to seismic regulations. Also, results from [8; 12] confirmed that HI and SED exhibit the strongest correlation, which confirms their influence obtained in this analysis on non-seismic designed buildings behavior.  
Finally, Table 10 compares various ground motion parameters and their correlation with the interstory drift ratio (IDR), which is a key measure of structural damage. It highlights that peak ground velocity (PGV) exhibits a high correlation (0.7-0.9) with the IDR, making it a crucial indicator for traditional metrics of structural performance during seismic events. In contrast, peak ground acceleration (PGA), commonly used in seismic design codes, shows only a low correlation (<0.3), suggesting it may not fully capture the structural response. Energy-based metrics such as specific energy density (SED) and Arias intensity (Ia) have high-to-significant correlations with the IDR, indicating their effectiveness in predicting structural damage due to accumulated seismic energy. Housner Intensity (HI), another important spectral velocity measure, is highly correlated with the IDR, making it particularly useful for evaluating mid-rise and high-rise buildings. Duration-based metrics like Uniform Duration (UD) and Significant Duration (SD) also influence structural response, with SD showing a moderate relationship with the IDR compared to UD. The table also reveals that fundamental seismic parameters, such as magnitude (M), have a relatively low correlation with IDR, indicating that energy-based and duration-based metrics are more reliable for assessing damage. The observed trends suggest that using a combination of these metrics provides a more comprehensive understanding of seismic impacts on structures. Overall, the table emphasizes the need to prioritize velocity and energy-based metrics over traditional measures like PGA when assessing seismic vulnerability and selecting suitable earthquake records for nonlinear dynamic time history analyses.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & **PGA** & **PGV** & **PGD** & **SED** & **ASI** & **HI** & **Ia** & **UD** & **SD** & & **R** \\ \hline  & **(g)** & **(cm/s)** & **(cm)** & **(cm\({}^{2}\)/s)** & **(g\(\cdot\)s)** & **(cm)** & **(m/s)** & **(s)** & **(s)** & **(s)** & **(km)** \\ \hline
**Zagreb** & 0.30 & **0.86** & 0.47 & **0.90** & 0.72 & **0.91** & 0.74 & 0.37 & 0.17 & 0.21 & 0.34 \\ \hline
**Dubrovnik** & 0.01 & **0.95** & 0.79 & **0.92** & 0.41 & **0.91** & 0.58 & 0.67 & 0.68 & 0.56 & 0.30 \\ \hline \hline \end{tabular}
\end{table}
Table 9: Correlation of normalized values for two earthquake scenarios.