Segmented Concrete Wind Tower Transition Rings
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Solution Overview
Problem
Existing wind tower construction methods, whether using steel or concrete, face limitations in height due to transportation constraints and complexity in geometry, with steel towers limited by section diameter and concrete towers being slow and weather-sensitive.
Innovation Solution
The design and pre-casting method for a stepped concrete wind tower using transition rings or annular anchor members to transfer post-tensioning tendon forces, allowing for uniform geometry and eliminating the need for external anchor blisters, with match-casting techniques and on-site formwork for efficient segment placement and grouting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If steel tubular sections are used to construct wind towers, then the tower can be assembled through bolting at intermediate flanges, but the tower height is limited by transportation constraints on steel section diameter
Solution Approach 1:
The wind tower is divided into multiple precast concrete segments that can be manufactured at regional facilities and transported to the site. Each segment is cast with a constant cross-section, eliminating the need for complex tapered forms. The segments are assembled vertically with match-cast joints, achieving heights exceeding 300 feet while using manageable section dimensions for transportation.
Solution Approach 2:
The invention changes the material from steel to concrete, fundamentally altering the structural parameters. Concrete allows for much greater heights without the same transportation constraints because the segments can be precast at regional facilities with constant cross-sections, eliminating the diameter limitations that constrain steel tower heights to approximately 300 feet.
2Adaptability or versatility
If cast in place construction methods are used for concrete towers, then the towers can be constructed using regional labor and materials, but the construction speed is reduced and the process is sensitive to weather conditions
Solution Approach 1:
The tower segments are precast at regional facilities before being transported to the wind farm site. This preliminary action allows the segments to be manufactured in controlled environments, independent of weather conditions, and then rapidly assembled on-site. The match-cast joint technology enables quick connection of segments without requiring grouting or secondary field operations, significantly accelerating construction compared to cast-in-place methods.
3Ease of manufacture
If conventional precast concrete techniques are used with vertical and horizontal joints, then the elements can be precast offsite, but post-tensioning in both directions is required to achieve a durable tower structure
Solution Approach 1:
The invention extracts and eliminates the complex post-tensioning system from the joint design. Instead of requiring post-tensioning in both vertical and horizontal directions, the match-cast joint technology creates monolithic connections between segments through precise formwork matching, removing the need for external anchor blisters and simplifying the overall structural system.
Solution Approach 2:
The match-cast process creates a precise copy of one segment's interface on the adjacent segment. The formwork for each segment is cast against the previously installed segment, ensuring perfect geometric matching. This copying approach eliminates gaps and misalignments that would otherwise require complex post-tensioning systems to secure the joints durably.
4Shape
If the tower geometry is tapered as is common in concrete wind towers, then the tower can achieve aerodynamic efficiency, but the forming system and reinforcement placement become more complex
Solution Approach 1:
The tower is segmented into discrete sections, each with a constant cross-section. The transition between different diameters occurs at the segment interfaces rather than through continuous tapering. This segmentation allows each segment to be formed with simple constant-cross-section forms, eliminating the complexity of tapered forming systems while still achieving the overall tapered appearance of the complete tower.
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 approach enables taller wind towers with simplified on-site construction, optimized lifting operations, and enhanced shear capacity, resisting external loads effectively through strategically placed post-tensioning tendons, while reducing construction time and weather sensitivity.
Implementation Method 1
One primary feature of the invention is the forming of a stepped tower, whereby transition rings or annular anchor members or donut sections are used to transfer the post-tensioning tendon forces into the sections of the tower.
Data Source
AI summary
A post-tensioned precast segmental concrete tower has a stack of annular segments with uniform cross-sections which varies over the tower height. The transition between tower segments occurs in stages and is achieved using annular members or segments which support and anchor post-tensioning tendons that transfer loads passing through the tower as a result of a change in tower geometry. The tower segments are match cast against one another in fabrication to create tight matching opposing surfaces when placed into the tower and to create tight joints. The match casting eliminates the need for grout between precast segments, resulting in a faster tower erection time and high durability of the joints. All annular segments have horizontal joints and no vertical joints. The tower geometry simplifies the formwork system used to precast the segments, and the post-tensioning tendons tie all segments together and to the foundation.