Pre-stressed Concrete Transition Element for Offshore Wind Turbines
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Solution Overview
Problem
Existing offshore wind turbine support structures face durability and fatigue issues at the transition zone between steel and concrete, particularly due to stress concentrations and the need for external reinforcing elements that increase weight and cost.
Innovation Solution
A pre-stressed concrete revolution layer with an axisymmetric circular transition geometry connects the tower and float, using circumferential and longitudinal tendons for smooth strain transmission, eliminating the need for external stiffeners and optimizing stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external rigidifying and reinforcing elements are added to the transition zone, then structural strength and durability are improved, but weight increases and buoyancy is reduced
Solution Approach 1:
The patent applies different material properties and reinforcement strategies at different locations. The transition element uses a specific geometry with optimized thickness distribution, and prestressing tendons are strategically placed in critical zones rather than uniformly throughout the structure. This localized approach provides strength where needed without adding unnecessary weight elsewhere.
Solution Approach 2:
The transition element combines concrete with prestressing tendons to create a composite structure. The concrete provides compression resistance while the prestressing tendons provide tension resistance, creating a synergistic effect that achieves high strength-to-weight ratio without requiring additional external reinforcing elements.
2Stability of the object's composition
If the diameter of the float is increased to maximize stability and buoyancy, then stability is improved, but stress concentrations at the transition zone increase
Solution Approach 1:
The transition element uses a curved, axisymmetric geometry that smoothly connects the tower base to the float. This curved transition distributes stresses more evenly compared to sharp angular transitions, reducing stress concentrations while accommodating the diameter change from tower to float.
Solution Approach 2:
The patent optimizes geometric parameters of the transition element, including its thickness profile and curvature radius, to balance stress distribution. The thickness is varied along the height to provide adequate strength at critical locations while maintaining overall轻量化 design.
3Volume of moving object
If the transition element length is reduced to minimize structure size, then compactness is improved, but stress concentrations and fatigue risks increase
Solution Approach 1:
The curved geometry of the transition element provides a gradual transition that distributes strains more evenly, reducing fatigue risks even in compact designs. The curvature acts as a stress-distributing feature that eliminates the need for longer transition zones.
Solution Approach 2:
Prestressing tendons are installed in advance to pre-compress the concrete structure, counteracting future tensile stresses from wave loading and fatigue cycles. This preliminary action enhances fatigue resistance without requiring additional structural length.
4Reliability
If the transition zone is kept away from water surface for durability, then exposure to aggressive environmental vectors is reduced, but connection complexity increases
Solution Approach 1:
The transition element is integrated monolithically with both the tower and float, eliminating the need for separate connection components. This merging of structures simplifies the connection while ensuring durability by keeping the transition zone below the water surface.
Solution Approach 2:
The transition element serves as an intermediary structure that connects the tower to the float substructure. By positioning this intermediary below the water surface, the design protects the connection zone from aggressive environmental conditions while maintaining structural integrity.
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 design enhances durability and reduces maintenance by uniformly distributing stresses, minimizing weight and cost while improving hydrodynamic behavior and allowing larger diameters for increased stability and buoyancy.
Implementation Method 1
The transition element comprises a pre-stressed concrete layer of revolution having an optimum geometry for the correct transmission of strains between the two parts, the tower and the float
Implementation Method 2
wherein the tower and float form a single part and the prestressing strains of the concrete generate considerable deflection strains in the geometry changes
Data Source
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AI summary
The invention relates to the embodiment, by means of a pre-stressed concrete layer, on floating structures for supporting wind turbines, of the transition zone between the tower, of a lesser diameter, and the concrete float, of a greater diameter, whether the tower is made of metal or concrete. Said layer of revolution has the optimum geometry for the correct transmission of forces between the two parts, the tower and the float, with a reduced thickness and without the need for external rigidifying and reinforcing elements on the surfaces thereof, which would increase the weight and the cost of the structure.