Split-Sleeve Drop-In Anchor for Cracked Concrete Locking
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Solution Overview
Problem
Conventional drop-in anchors fail to provide sustained expansion in seismic conditions or cracked concrete due to limited radial expansion of the expansion sleeve, leading to safety risks and potential damage to the target structure.
Innovation Solution
A fastener design featuring a main body with a tubular portion and a split portion that tapers towards the tubular portion, surrounded by an expansion sleeve that extends to the lower end of the tapered section, allowing for greater radial expansion and smooth sliding, reducing the risk of damage and ensuring a secure engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the expansion sleeve only surrounds the neck and upper part of the tapered portion (as in conventional design), then the device complexity is reduced, but the radial expansion capability is insufficient and projections are needed which damage the hole walls
Solution Approach 1:
The expansion sleeve is divided into multiple clip segments that can expand radially outwardly. This segmentation allows the sleeve to expand progressively and uniformly without requiring damaging projections, resolving the contradiction between simple structure and reliable engagement.
Solution Approach 2:
The expansion sleeve extends to surround the entire tapered portion, utilizing the longitudinal dimension to maximize radial expansion capability. This dimensional extension eliminates the need for projections while ensuring reliable engagement through sustained expansion along the full length of the tapered section.
2Device complexity
If the tapered portion is partially covered by the expansion sleeve, then the device complexity is reduced, but friction holds up backward sliding and prevents sustained outward expansion under seismic conditions
Solution Approach 1:
The split portion is divided into multiple segments that can move independently relative to each other. This segmentation reduces friction between the tapered portion and expansion sleeve by allowing slight relative movements, enabling sustained outward expansion even under seismic conditions while maintaining a simpler covered design.
3Reliability
If projections are formed on the outer surface of the expansion sleeve to achieve tight engagement, then the engagement reliability is improved, but the hole walls are damaged during installation or expansion
Solution Approach 1:
The expansion sleeve is segmented into multiple clip segments that expand radially outwardly. This segmentation provides the necessary engagement reliability through distributed contact points without requiring protruding projections, thereby avoiding damage to the hole walls during installation or expansion.
Solution Approach 2:
The clip segments are designed to change their radial dimension dynamically during expansion. This parameter change allows the segments to engage tightly with the hole walls through controlled radial movement rather than through fixed projections, eliminating hole wall damage while maintaining engagement reliability.
4Ease of manufacture
If the expansion sleeve does not extend to the lower end of the tapered section, then the ease of manufacture is improved, but the radial expansion is insufficient for seismic conditions or cracked concrete
Solution Approach 1:
The expansion sleeve is constructed from multiple clip segments that can be manufactured separately and assembled. This segmentation allows for easier manufacturing of the full-length sleeve that extends to the lower end of the tapered section, while the segmented structure enables the necessary radial expansion for seismic conditions and cracked concrete applications.
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 design achieves a reliable locking engagement in cracked or seismic conditions by enabling sustained outward expansion and minimizing friction, ensuring a secure hold without damaging the target structure.
Implementation Method 1
inserting a plug from the threaded hole to the lower part to expand the segments outwardly in order to achieve a frictional engagement
Implementation Method 2
achieve a frictional engagement between outer surface of the segments and walls of the pre-formed hole
Data Source
AI summary
A fastener includes a main body having a tubular portion and a split portion that extends from a lower end of the tubular portion, and longitudinally includes a tapered section that tapers in a direction towards the tubular portion. The fastener further includes an expansion sleeve annularly surrounding the split portion, wherein the expansion sleeve longitudinally extends to a lower end of the tapered section.