As interest in wind power continues to grow, so too has the scale and complexity of wind turbines and their towers, making soil-structure interaction, structural dynamics, and frequency response increasingly important. Numerical simulation is well-suited to capture the behavior of existing and novel designs for these large structures, in a variety of ground conditions – including offshore, to ensure that they satisfy their design criteria.

Itasca’s commercial software FLAC3D is well suited for this type of geotechnical analysis, because it can continuously follow the nonlinear stress-strain response to loading of soils, rock, and concrete. An accurate solution is provided for loads, moments, and deformations at all instances in the loading process. Rather than model the entire tower, the weight and rotational load, representing the tower loading, are applied through a single ring of tower zones.

Itasca has performed analyses to evaluate the effects of site conditions (specifically, the strength and stiffness of the foundation rock) on the foundation rotational stiffness and anchor bolt loads for a range of tower overturning moments for several wind farms, including off-shore.