A-frame foundation system for single-axis trackers with weak axis support
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Solution Overview
Problem
Conventional single-axis solar tracker foundations, such as monopiles, are inefficient due to the need for over-specified strength and depth to resist both bending and axial loads, leading to wasteful use of materials and potential failure under weak-axis forces.
Innovation Solution
The use of A-frame-shaped truss foundations that translate both lateral and axial loads into tension and compression forces, allowing for smaller, lighter steel components and reduced embedment depth, with configurations like double-truss and five-legged truss systems providing comprehensive weak-axis support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If monopile foundations are used to support single-axis trackers, then the structure can withstand bending moments from wind loads, but the foundation requires over-specified strength, weight and depth leading to material waste
Solution Approach 1:
The monopile foundation is segmented into multiple A-frame truss elements arranged in a circular pattern. Each truss leg is a separate structural member that collectively provides the required strength, allowing each individual member to be smaller and more efficient than a single monopile.
Solution Approach 2:
The foundation transitions from a single vertical monopile to a three-dimensional A-frame truss structure with legs extending at angles from the vertical axis. This dimensional change allows the structure to resist bending moments through geometric configuration rather than relying solely on the strength of individual vertical members.
2Strength
If single structural members are used to resist bending moments, then the foundation can withstand wind loads, but much larger beams must be used than required for weight support alone
Solution Approach 1:
The single large bending-resistant beam is segmented into multiple smaller truss legs working together. Each leg carries a portion of the total load, and the collective arrangement provides the necessary bending resistance without requiring any individual member to be oversized.
Solution Approach 2:
The foundation uses a composite arrangement of multiple structural members (truss legs, bracing elements, cross-bracing) that work together to provide bending resistance. This composite structure achieves the required strength with smaller, more efficient individual components compared to a single monolithic beam.
3Loss of substance
If A-frame truss foundations are used to translate lateral loads into axial forces, then smaller foundation components can be used, but weak-axis forces still introduce bending moments in the A-frame legs
Solution Approach 1:
The A-frame truss is segmented into multiple legs arranged in a circular pattern around the vertical axis. This segmentation allows the structure to resist weak-axis forces through the collective action of multiple members rather than relying on bending resistance of individual A-frame legs.
Solution Approach 2:
The foundation adds a horizontal dimension by arranging truss legs in a circular pattern and incorporating horizontal bracing elements. This multi-dimensional arrangement enables the structure to resist weak-axis forces through axial tension and compression in multiple members rather than bending in single members.
4Stability of the object's composition
If monopile foundations are driven to sufficient depth to resist bending, then the structure is stable, but the risk of encountering hard soils increases
Solution Approach 1:
The single deep monopile is replaced by multiple shallower truss legs distributed around the foundation area. This segmentation reduces the embedment depth required for each individual member while maintaining overall foundation stability through the collective action of multiple members.
Solution Approach 2:
The foundation transitions from a single vertical element to a three-dimensional truss structure with legs extending at angles and horizontal bracing. This dimensional change provides stability through geometric configuration and load distribution across multiple members at shallower depths, reducing the risk of encountering hard soils.
Data Source
AI summary
A single-axis tracker supported by multiple A-frame-shaped single-truss foundations that translate lateral loads into axial forces of tension and compression, and at least one truss foundation supporting the torque tube drive motor or other tracker component subject to axial loads to provide support for lateral loads as well as loads oriented along the axis of the torque tube.