Dynamic analysis of cylindrical foundations under torsional loading via generic discrete-element models simulating soil stratum

Torsional vibration, considering soil-structure interaction, is essential to the dynamic response of most irregular structures. A systematic method is developed to seek the optimal simplified model among multiple model candidates for uniform soil on rigid base regarding dynamic soil-foundation interactions. A generic model is identified by the proposed method to simulate the cylindrical foundation resting on or embedded in the soil stratum under torsional vibrations. Various soil-foundation parameters, mainly including embedment depth, layer depth, and mass ratios, are considered in the simplified analysis. The frequency-magnification curves and resonant responses of the foundation using the generic model agree well with theoretical solutions. The resultant resonant magnification factors against mass ratios clearly illustrate the impacts of the whipping effect resulting from the soil-foundation interactions. The generic model performs better and adopts fewer parameters than the existing model to simulate the soil-foundation interactions. In addition, dimensionless parametric charts are presented to estimate foundation responses for engineering applications quickly. The proposed charts also significantly overcome the limitations of the Wolf and Paronesso model. The generic model shows efficiency and accuracy in simulating the soil stratum. This research could contribute to the foundation vibration analysis for torsional responses.