Lift Anchor With Threaded Legs For Precast Concrete
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Solution Overview
Problem
Existing lift anchors for precast concrete components are not economical to manufacture and are not compatible with a range of reinforcement materials, particularly in thin sections, limiting their adaptability and effectiveness.
Innovation Solution
A lift anchor design featuring a centrally positioned handle and downwardly extending legs with projections, such as threads, that distribute stress along the legs' length, allowing for increased load-bearing capacity and compatibility with various reinforcement materials, including rebar and multi-ply cables, while enabling concrete to flow around the anchor for enhanced strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If projections are added to the legs to distribute stress, then load-bearing capacity increases, but manufacturing complexity increases
Solution Approach 1:
The leg is segmented into multiple projection elements along its length, with each projection providing localized stress distribution. This segmentation allows the load to be divided and borne by multiple discrete points rather than concentrated at a single location, increasing overall load-bearing capacity while keeping each individual projection simple to manufacture
Solution Approach 2:
Projections are provided only on the legs where stress distribution is needed, while the handle remains smooth for proper engagement with lifting equipment. This localized application of projections ensures that manufacturing complexity is introduced only where mechanically necessary, rather than uniformly across the entire anchor structure
2Adaptability or versatility
If the anchor is designed for thin sections, then adaptability to various precast components improves, but the anchor's structural strength may be compromised
Solution Approach 1:
The anchor utilizes the third dimension by extending projections along the length of the legs rather than relying solely on the cross-sectional dimensions. This longitudinal distribution of stress-bearing elements allows the anchor to achieve high load-bearing capacity even when the overall size is constrained for use in thin precast sections
Solution Approach 2:
The projections are pre-formed on the legs before insertion into the precast component, creating immediate mechanical interlock with the concrete as it sets. This preliminary structural configuration ensures that even in thin sections, the anchor establishes strong bonding and stress distribution from the outset, compensating for the limited available concrete thickness
3Ease of operation
If the handle is made smooth for easy engagement, then ease of operation improves, but the handle's structural strength may be reduced
Solution Approach 1:
The handle is extracted from the projection pattern applied to the legs, creating a distinct smooth zone specifically for engagement with lifting equipment. This separation allows the handle to be optimized for operational ease while the legs retain the projections needed for structural strength, with the handle's smooth surface preventing stress concentrations that would compromise either engagement or strength
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 anchor design enhances the load-bearing capacity and pull-out strength, ensuring secure lifting of precast concrete components, particularly in thin sections, by distributing stress and allowing concrete to fully penetrate the anchor, thereby minimizing the risk of fracture and improving manufacturing efficiency.
Implementation Method 1
The projections are designed to increase the load bearing capacity of the lift anchor by distributing stress along the length of each of the legs
Implementation Method 2
The pitch, height of the projections and angle of the sides of the projections relative to the axis of the legs are selected to allow the concrete to flow into the gaps between projections
Implementation Method 3
the underside of the handle may be free where it is in contact with the lifting tackle. Accordingly, when the anchor is employed to lift a precast concrete structure by engaging a hook or other lifting tackle with the handle, the hook or tackle may readily slide to the highest point of the anchor handle
Data Source
AI summary
A precast concrete component is provided with anchor having a cylindrical rod bent to form a centrally-positioned handle and two downwardly extending legs. The handle can be relatively smooth and die legs are provided with a series of projections along their lengths, such as are formed by threads. The legs of the anchor may converge inwardly from the handle and are compatible with precast concrete double tees having webs or stems that taper from the flange of the double tee downward. Alternatively, the legs of the anchor may diverge outwardly from the handle.