Probabilistic equivalent linear soil spring stiffness analysis for gravity platforms: Conceptual model

Horizontal and rotational soil spring stiffnesses of the foundation are needed (a) to perform the dynamic analysis of gravity platforms and (b) to obtain characteristic wave loads to be used in the geotechnical design analysis of platforms. Dynamic analyses are especially important in the design of deepwater platforms. A probabilistic procedure in the context of the first two moments is suggested to estimate the equivalent linear soil spring stiffnesses of the foundation for gravity platforms on clay loaded under undrained conditions. In calculating the first two moments of the soil spring stiffnesses, consideration is given to the influence of the uncertainties in the loads and soil properties, and the model errors encountered in applying the deterministic procedure. Limitations in the available data, the current analytical procedures, and in the probabilistic analysis are discussed. The companion paper [1] provides an illustrative example on the same topic.