Presentation Description: With the growing increase in turbine capacity, the aspects dictating foundation design are changing. Given the rise in the normal turbine operational loads , which to have more stringent requirements in the design standards, designs have required significantly larger foundations with proportional increases in cost.
There is increasing interest in the wind industry to optimize the foundation design and to reduce the overall project costs. Designing smaller foundations would reduce overall costs, but one major controlling limit is the requirement for the foundation contact area and the “no-gapping” limit. Currently there is no clear guidelines available to assess the risk of cyclic soil degradation under foundations that are gapping and thus are generally not allowed per the design codes.
While further studies and industry discussions are underway, this presentation introduces the issue, provides additional background, explains traditional solutions used in the industry, discusses the new and innovative methods considered to reduce the size and cost of the foundations, and summarizes the state of the art on this subject and the major sources of disagreement on the interpretation of the standards.
Upon completion, participant will be able to describe the main causes of increased costs of turbine foundations. The gap between the higher extreme wind loads and typically lower operational loads is reducing with newer, larger and more advanced turbines. Historically, foundation design was dictated by extreme wind loads. However, with the increase in operational loads, the size in most cases is controlled by the more stringent requirements under operational loads. In this presentation a summary of the foundation design aspects affected by this change will be discussed.
Upon completion, participant will be able to describe the long-term consequences of cyclic loads on the foundation subgrade and understand how the turbine operation may be affected by the gradual loss of foundation stiffness. A short introduction to different means and method to assess the foundation and optimize the design will be presented.
Upon completion, participant will be able to understand the main sources of disagreement in the industry on the risk level assessment and engineering tools and analysis that could help in resolving it. Investors and developers in the wind industry have been asking for a more conclusive method for risk categorization. In this presentation, the state of the art of foundation design with respect to subgrade cyclic degradation will be described and the ongoing and innovative efforts and methods to develop a more realistic and less conservative design approach will be discussed.