Estimation of Wind Turbine Foundation Rotational Stiffness Based on Fully Non-Linear Dynamic Analysis-Video

Video Transcription

Video Summary

The presentation examines how to estimate wind turbine rotational stiffness using fully nonlinear dynamic analysis, with a focus on intermediate pier-type foundations. As turbines grow taller and more powerful, foundation demands and the importance of soil–structure interaction increase. Current industry practice often relies on simplified linear spring stiffness requirements to keep the turbine’s natural frequency between its 1P and 3P operating frequencies.<br /><br />The researchers modeled a turbine, foundation, and surrounding soil in PLAXIS 3D, applying an acceleration time history at the nacelle. Preliminary analyses compared pier lengths of 20–32 feet using a medium-dense sand model. Reducing pier length from 32 to 28 feet produced little change in frequency response, although rotational stiffness and foundation behavior varied, possibly due to a shift from rigid-body rocking toward partial fixity and flexure. Even a small number of load cycles affected estimated stiffness.<br /><br />The findings are preliminary; future work will improve soil models and assess long-term cyclic behavior.

Keywords

wind turbine

rotational stiffness

soil-structure interaction

PLAXIS 3D

foundation analysis