<p>Structures modelled with flexible-base assumptions, incorporating soil effects, generally exhibit longer natural periods and higher damping compared to fixed-base models that exclude soil-structure interaction (SSI). However, the beneficial or detrimental nature of SSI remains contentious in current earthquake damage analyses and research findings. This study introduces a numerical modelling technique, validated by experimental shaking table tests, to examine the effects of SSI on high-rise buildings. The study considers various substructure parameters, including foundation types, soil types, and bedrock depths. Both advantageous and adverse impacts of SSI are identified and analysed. Numerical simulations reveal that increased subsoil stiffness significantly amplifies the base shear of structures compared to bedrock depth effects. Additionally, increased foundation rocking results in higher inter-storey drifts and reduced base shear. Overall, SSI tends to amplify inter-storey drifts, indicating detrimental effects. Specifically, the study found that the inclusion of SSI increased maximum inter-storey drifts by up to 38%, particularly in softer soils, while reducing base shear by up to 44% in structures with classical compensated foundations on D_e and E_e soil types. In contrast, piled foundation systems experienced an increase in base shear of up to 27% under the same conditions. Conversely, SSI has beneficial impacts on base shear for structures with classical compensated foundations on soil types of D_e and E_e, as it reduces the base shear. For structures with piled foundations and those with classical compensated foundations on C_e soil, SSI effects are detrimental. C_e, D_e, and E_e soils correspond to geotechnical classifications per AS1170, representing stiff, medium, and soft soils respectively. The study also presents minimum base shear ratios considering SSI reduction effects for various foundation types.</p>