The effect of soil (as a supporting medium) on the dynamic analysis results of frame foundation was studied by considering soil stiffness as elastic support (with the specific moduli of subgrade reaction) and simulating weak as well as dense soil types. In addition, simulations of soil as a continuum medium were also examined to clarify the effect of different simulated soil types in comparison with the neglect of a soil type when assuming a rigid base of raft foundation. The findings suggested that soil stiffness must be incorporated into dynamic analyses to accurately predict the dynamic response of frame foundations under dynamic loading. Generally, increasing the soil subgrade reaction reduced the calculated displacement response of a foundation by a ratio of 2.88:21.04 depending on the stiffness of the soil; the softer the soil, the more the ratio observed. The calculated natural frequency difference between the fixed and elastic support assumptions ranged from 9.52 Hz to 19.21 Hz in the vertical direction. The assumption of a fixed base, neglecting the soil effect, underestimated the dynamic displacement responses of the frame foundation by 30%, while elastic support overestimated the displacement responses by 30% approximately; in both cases, the displacement response ratio was compared to the assumption of soil as a continuum. These results emphasise the importance of considering soil as a continuum in the analysis and design of high-speed turbo-machine foundations; this approach ensures accurate predictions of dynamic behaviour, avoiding resonance and vibration amplification. This study, comprehensively analysing the dynamic behaviour of high-speed turbo-machine frame foundations, offers valuable insights into the effects of soil stiffness on the same. Its findings indicate the need for rigorous geotechnical and structural analysis that can enhance the design and performance of these critical structures.