Dynamic machine foundations can be considered as a necessary component of the industrial infrastructure. Design of the dynamic equipment foundations has, however, traditionally been grounded on a rule of thumb that is inaccurate and rigid to use at the discretion of the engineers. The conventional rule of thumb, which includes minimum weight ratios and resonance avoidance criteria, has been used singularly with two poles, which can be either conservatively designed systems that are too heavy, or systems that are going to experience too much vibration and fatigue. This paper presents a novel, analytical framework for the reinterpretation of traditional design practices, using a physics-based approach, and results in a single, unified overall performance metric: the Combined Safety Index (CSI). The method utilizes frequency-dependent soil-foundation interaction models, allowing for a systematic evaluation of both inertially related and resonantly related stability under harmonic excitations. Using large-scale validations of real-world, global operational and geotechnical data from numerous case studies, including centrifugal compressors, blowers, and horizontal equipment, the reliability of the framework was demonstrated to be high (> 97%), with greater than 97% of the simulated designs meeting CSI ≥ 1.0. In addition, the method allows for mass optimization resulting in reductions in the amount of concrete used, and thus reductions in cost and environmental impact, of up to 45%. Unlike rule-of-thumb methods, this model allows designers to make informed decisions regarding the trade-off between the amount of mass of the foundation and detuning of the operating frequency, and thus supports economic efficiency and environmental sustainability. Statistical analyses, including local and global sensitivity analysis and Monte Carlo uncertainty quantification of the results, confirmed that the primary variables controlling system safety are the damping ratio (ζ) and the mass of the foundation (Wf). This work therefore provides practicing engineers with a practical, computationally efficient tool for designing safer, more sustainable foundations, and assists in advancing the state-of-the-art in design practice and in advancing digital engineering. © Springer Nature Switzerland AG 2026.
