Monopile Modeling with Distributed Moment and Base Shear

The patent changes the fundamental parameters of the soil-structure interaction model by introducing distributed moment, base moment, and base shear force in addition to distributed lateral load. This transforms the Winkler Model into a more comprehensive model that accounts for rotational stiffness and moment effects, which are critical for large diameter monopiles with small length-to-diameter ratios. The new model uses modified soil reaction curves (p-y, t-z, and q-z curves) to represent these additional parameters, enabling more accurate modeling of the complex soil-structure interaction behavior.

The patent extends the PISA Model to achieve universality by integrating capabilities to handle lateral loading, axial loading, and combined loading conditions within a single unified framework. The model incorporates axial load transfer through the pile shaft and base, allowing it to simulate various loading scenarios including pure lateral loading, pure axial loading, and their combinations. This multi-functional capability makes the model adaptable to different monopile design situations and loading conditions.

The patent introduces standardized soil reaction curves (p-y curves for lateral load, t-z curves for shaft friction, and q-z curves for base resistance) as intermediary elements that mediate between the complex soil-structure interaction and the structural response. These standardized curves serve as pre-determined, empirically-based relationships that can be directly applied without requiring new field testing for each project. The curves act as transfer functions that convert displacement inputs into reaction force outputs, simplifying the implementation while maintaining accuracy.

The patent adds another dimension to the soil-structure interaction model by incorporating rotational stiffness and moment effects alongside the traditional lateral load-displacement relationship. The new model considers not only the horizontal displacement of the pile but also the rotation of the pile cross-section and the resulting distributed moment and base moment. This dimensional expansion allows the model to capture the coupled lateral-flexural-torsional behavior that occurs under concurrent wind, wave, and current loads, providing a more realistic representation of the physical system.