Wood Anchoring Device with Differential Tie Lengths
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Solution Overview
Problem
Anchoring devices for wood structures, particularly roofs, face challenges in distributing load evenly across fasteners, leading to potential wood fracture or detachment during falls, especially when loaded perpendicular to the thin side of dimensional lumber, which is prone to splitting or tearing.
Innovation Solution
A wood roof anchor with a connecting ring and multiple ties of varying lengths, designed to distribute tensile loads evenly by differential stretching, ensuring that at least one tie remains unbroken under a 900-pound load, and featuring a D-ring configuration for secure attachment to wood structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If screws are disposed mid-way along the thin side of dimensional lumber, then the anchoring device can be installed, but the threaded shafts pry against a relatively thin section of wood (less than 3/4 inches) and readily fracture or split the wood and tear out
Solution Approach 1:
The patent positions fastening holes asymmetrically relative to the centerline of the anchoring device, specifically offsetting them toward the thicker portion of the dimensional lumber. This asymmetric positioning ensures that fasteners engage the thicker, stronger portion of the wood (greater than 3/4 inches) rather than the thin edge, thereby preventing wood fracture and tear-out while maintaining installation feasibility.
2Strength
If multiple fasteners are used to distribute load, then anchoring strength is improved, but the complexity of the anchoring device increases
Solution Approach 1:
The anchoring device is segmented into multiple functional components: the main body, multiple ties of varying lengths, and multiple fastening holes positioned at different locations. This segmentation allows the load to be distributed across multiple fasteners and ties, with each component performing a specific function in the load distribution system, thereby achieving high anchoring strength without excessive overall complexity.
3Strength
If ties of varying lengths are used to equalize forces, then load distribution is improved, but the device complexity increases
Solution Approach 1:
Different ties are assigned different lengths and stiffness properties based on their specific functional requirements. Ties with varying lengths are strategically positioned to equalize forces applied to fastening holes during dynamic loading, with each tie's local properties optimized for its specific location and load path, achieving superior load distribution without requiring complex overall device design.
4Adaptability or versatility
If the anchoring device is positioned to engage thin side of lumber, then installation flexibility is improved, but the risk of wood fracture under perpendicular loading increases
Solution Approach 1:
The patent positions fastening holes at multiple dimensions and orientations within the anchoring device body, not just along a single line. This multi-dimensional positioning allows the fasteners to engage the thicker portion of the lumber even when the device is installed on the thin side, effectively using the third dimension (depth into the wood) to overcome the limitation of thin-side installation and prevent wood fracture under perpendicular loading.
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
Enhances the energy absorption capacity and load distribution across fasteners, reducing the risk of wood fracture and providing effective fall protection by maintaining structural integrity under dynamic loading conditions.
Implementation Method 1
At least two of the at least two ties have respective closed fastening holes at the anchoring ends thereof that are available for fastening the device to the anchorage. At least one of the at least two ties may have a length that is substantially different from a corresponding length of at least one other of the at least two ties, the different lengths providing for responding to tensile loading by stretching differentially and thereby assisting in equalizing the forces applied to the fastening holes.
Data Source
AI summary
A wood anchoring device having a connecting ring defining a closed connecting aperture and at least two ties, at least two of the at least two ties having respective fastening holes at anchoring ends thereof. The device may be fastened to the thin side of a 2×N piece of lumber through the fastening holes, wherein the at least two of the at least two ties are on the same side of the connecting ring relative to the axis of a test tensile load applied to the connecting ring in a direction perpendicular to the elongate axis of the piece of lumber. At least one of the ties has a length that is substantially different from a corresponding length of at least one other tie, the different lengths providing for responding to tensile loading by stretching differentially and thereby assisting in equalizing the forces applied to the fastening holes.