Wind Turbine Foundation Using Inclined Struts and Hollow Shaft
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Solution Overview
Problem
Conventional foundation systems for wind towers are costly and time-consuming due to high material requirements and sensitivity to weather conditions, and existing solutions either require excessive concrete or generate bending forces that can harm the tower structure.
Innovation Solution
A foundation system featuring a hollow central shaft with prefabricated dowels or rings, inclined struts, and a lower slab that utilizes soil weight as ballast to reduce material usage while effectively transmitting loads to the ground, incorporating pre-stressing systems and prefabricated elements for efficient installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional gravity-based foundations with large concrete slabs are used, then high external loads can be supported, but material costs and construction time increase significantly
Solution Approach 1:
The foundation is divided into a lower slab and an upper slab connected by vertical dowels or rings. This segmentation allows the foundation to function as an integrated structure while using significantly less concrete than a solid slab, resolving the contradiction between load support capacity and concrete volume.
Solution Approach 2:
The tower structure is nested within a hollow central shaft that extends from the lower to the upper slab. This nesting allows the tower and foundation to share structural loads efficiently, reducing the amount of concrete needed while maintaining high load support capacity.
2Reliability
If large volume in-situ concrete construction is used, then sufficient weight is provided to support tipping stresses, but construction time increases and weather sensitivity increases
Solution Approach 1:
The lower slab, upper slab, and connecting dowels/rings are prepared as integrated structural elements before final assembly. The hollow central shaft is also prepared in advance, allowing for rapid assembly that reduces construction time and weather sensitivity while maintaining stability against tipping.
3Quantity of substance
If radial ribs are added to concrete slabs, then external loads are better supported with smaller slab volume, but bending forces increase that can harm the tower structure
Solution Approach 1:
Instead of adding radial ribs that create bending forces, the invention uses vertical dowels or rings that transfer loads directly through compression. This inverted approach eliminates the harmful bending forces while still achieving load support with reduced concrete volume.
Solution Approach 2:
The mechanical system of radial ribs creating bending moments is replaced with vertical dowels or rings that transmit loads through axial compression. This substitution eliminates bending forces on the tower while maintaining load support efficiency.
4Productivity
If prefabricated elements are used, then construction time is reduced and in-situ industrialization is facilitated, but material handling complexity increases
Solution Approach 1:
The lower slab, upper slab, and connecting dowels/rings are designed as integrally connected prefabricated elements. This merging reduces the number of separate components that need to be handled and assembled, thereby reducing handling complexity while maintaining the productivity benefits of prefabrication.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly reduces material costs and construction time while maintaining structural integrity, allowing for better load distribution and increased stability with minimal material increase, optimizing material usage, deadlines, and execution quality.
Implementation Method 1
a pre-stressing system for connecting said strut with said central shaft and with said lower elements of the foundation system
Implementation Method 2
maximizing the proportion of the total weight of the foundation by gravity obtained from the weight of soil that gravitates on it
Data Source
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AI summary
Foundation system for towers, especially for onshore wind turbines, comprising a central shaft buried or partially buried, preferably hollow and formed by dowels made from precast concrete, an essentially flat lower slab and completely buried, and lateral support means in the form of inclined struts that are joined at their upper end with the central shaft and at its lower end with the lower slab, and that are preferably entirely buried. The wind tower is located on the partly buried main shaft. The foundation system may comprise other lower elements connected with the lower slab, such as radial ribs or peripheral beams. The struts are preferably prefabricated elements incorporating an efficient and economical connection system by pre-stressing. The foundation system maximizes the fraction of the weight of the foundation by gravity generated by soil or ballast material, allowing an important economy in the structural materials of the foundation.