Modular Pre-cast Concrete Foundation for Wind Turbines
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Solution Overview
Problem
Existing concrete foundation designs for cell phone and wind turbine towers face challenges such as in situ casting issues in harsh weather, transportation difficulties due to large module sizes, and inefficient post-tensioning methods, leading to increased costs and reduced strength.
Innovation Solution
A modular concrete foundation system comprising pre-cast base members and cylindrical pipe members with anchor rods for post-tensioning, allowing for controlled off-site assembly and transportation, eliminating the need for additional components and optimizing compressive loading while minimizing tensile stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If in situ casting is used for concrete foundations, then some components can be cast at the installation site, but proper curing is inhibited or prevented in harsh weather conditions
Solution Approach 1:
The foundation is divided into multiple pre-cast concrete segments (first through fourth segments) that are manufactured separately in controlled environments and then assembled on-site. This segmentation allows each segment to be cured under optimal conditions before installation, eliminating weather-related curing issues while maintaining on-site assembly flexibility.
Solution Approach 2:
The concrete segments are pre-cast and pre-cured at a manufacturing facility before being transported to the installation site. This preliminary action of casting and curing in controlled conditions ensures proper concrete strength development regardless of on-site weather conditions, resolving the contradiction between on-site casting capability and curing quality.
2Strength
If a solid non-modular base slab is used, then the foundation can support large tower loads, but transportation via truck becomes difficult and expensive
Solution Approach 1:
The base slab is segmented into multiple transportable concrete segments that can be individually loaded onto trucks. Despite being divided for transportation, the segments are designed with interlocking features and post-tensioning connections that, when assembled, create a unified structure with the required load-bearing capacity for large towers.
Solution Approach 2:
The modular segments are designed to nest or interlock with each other during assembly, forming a compact yet structurally sound base slab. This nesting approach allows the segments to be transported separately while assembling into a unified structure that maintains the strength required for supporting large tower loads.
3Strength
If additional thickness and reinforcement are added to the crown slab to withstand bending forces, then structural strength is improved, but additional weight negatively exerts compressive forces on the cruciate members requiring thicker construction
Solution Approach 1:
The crown slab is divided into multiple segments that are pre-cast separately and then assembled on-site using post-tensioning techniques. This segmentation allows each segment to be thinner and lighter while the post-tensioning connections provide the necessary bending resistance, eliminating the need for excessive thickness and reinforcement in each individual segment.
Solution Approach 2:
The patent changes the structural parameters by introducing post-tensioning elements that provide tensile strength to counteract bending forces. This allows the crown slab segments to be designed with reduced thickness and reinforcement compared to traditional solid slabs, as the post-tensioning cables carry the tensile loads that would otherwise require excessive concrete reinforcement.
4Adaptability or versatility
If flexible cables are used for post-tensioning, then the system can accommodate curved cable runs, but curved paths decrease strength and resistance to lateral forces
Solution Approach 1:
Instead of using flexible cables that must follow curved paths, the patent inverts the approach by using rigid straight post-tensioning bars or strands that are directly anchored between segments. This straight-line configuration maximizes the efficiency of the post-tensioning force in resisting lateral loads, while the segments themselves are positioned and oriented to accommodate the desired geometric configuration of the foundation.
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
The modular system enables efficient on-site assembly under controlled conditions, reduces transportation costs, enhances structural integrity by distributing loads evenly, and improves resistance to lateral forces, thus providing a cost-effective and robust foundation solution.
Implementation Method 1
a plurality of anchor rods, corresponding in number to said plurality of longitudinally-extending anchor rod containing apertures in said pipe members, each positioned in a corresponding of said anchor rod containing apertures in said pipe members, one end of each of said plurality of anchor rods positioned in a corresponding one of said anchor rod retaining apertures in said base members and at another mutually-opposite end having tensioning means imparting a tensile loading on each of said anchor rods; wherein said plurality of anchor rods pass through a respective of said anchor rod containing apertures and when tensioned impart a compressive load on said pipe members to retain same together
Data Source
AI summary
A modular foundation design for supporting a wind turbine or telecommunication tower, comprised of pre-cast concrete modules offering advantages of off-site manufacture and ease of transportation, but which deign is simple to construct. A base slab is provided comprised of sub-modules/base members arranged together in juxtaposed position which together provide a horizontal surface on which pre-cast pipe members may be stacked in end-to-end position to form a pedestal. Anchor rods extend through the pipe members into screw retainers in the base members, which rods serve to not only post-tension the pipe members and secure them together, but further advantageously serve to retain the base members together thereby assisting in distributing forces and loads applied to one sub-module/base member over the entire base slab. Coupling means to further couple the base members together may be added to better retain the base members together and still further improve distribution of forces.