Correlation Analysis Between Structural Seismic Response and Ground Motion Parameters Considering SSI Effects

Investigating the relationship between ground motion intensity measures (IMs) and structural responses is fundamental to seismic hazard assessment and performance-based structural design. However, most existing studies are based on the fixed-base assumption, where foundation flexibility is neglected, limiting the understanding of the effects of Soil–Structure Interaction (SSI) on IM–engineering demand parameters (EDPs) correlations. This study systematically evaluates the correlations between various IMs and EDPs while explicitly accounting for SSI effects, with particular emphasis on the influence of ground motion type (near-fault and far-field records). The results indicate that SSI modifies the correlations between IMs and structural responses, although its influence varies among different categories of IMs. For acceleration-based IMs, SSI has a limited impact on their relative effectiveness, preserving their ranking despite moderate changes in correlation coefficients. Velocity-based IMs consistently exhibit the strongest correlations with structural responses; however, their relative performance is strongly dependent on the characteristics of the input ground motions. In contrast, displacement-based IMs demonstrate substantial sensitivity to both soil conditions and ground motion characteristics, resulting in pronounced variability in their predictive capability across different seismic scenarios. These findings highlight the important influence of SSI in IM–EDP correlation analysis and emphasize the necessity of incorporating foundation flexibility when selecting candidate IMs for seismic performance assessment. The results are expected to improve the understanding of IM–response correlations in SSI systems and may help inform the preliminary screening of candidate IMs for performance-based earthquake engineering applications