Dual-Thread Concrete Anchor for Cracked Concrete Pullout Strength
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Solution Overview
Problem
Existing concrete anchors face challenges in meeting pullout requirements, especially when installed in cracked concrete, and are often complex and costly, with screw type anchors failing to provide sufficient holding strength and multi-piece anchors being labor-intensive and expensive.
Innovation Solution
A one-piece threaded concrete anchor with a unique helical thread formation featuring alternating lobe members and base portions, which reduces installation torque and enhances resistance to pullout by varying thread heights and widths, allowing deeper penetration and better engagement with cracked concrete.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If screw anchors are used, then installation is simple and cost-effective, but holding strength is insufficient in cracked concrete
Solution Approach 1:
The patent modifies the thread geometry parameters by creating a dual-thread formation with alternating high and low thread heights. The high threads engage the concrete for holding strength while the low threads provide spacing and concrete displacement, enabling the anchor to achieve wedge-type performance in cracked concrete while maintaining screw anchor installation simplicity
Solution Approach 2:
The thread formation is segmented into alternating high and low thread portions along the shank length. This segmentation allows different portions of the thread to perform different functions: high threads provide engagement and holding strength, while low threads provide spacing and concrete displacement, resolving the contradiction between simple installation and high holding strength
2Strength
If multi-piece anchors are used, then holding strength in cracked concrete is achieved, but device complexity and cost increase significantly
Solution Approach 1:
The patent merges the functions of multiple anchor components into a single integrated threaded shank with a unique dual-thread formation. The alternating high and low threads combine the engagement function of screw anchors with the expansion and spacing functions of wedge anchors, eliminating the need for separate components while achieving equivalent holding strength in cracked concrete
3Strength
If multi-piece anchors are used, then holding strength in cracked concrete is achieved, but installation labor intensity increases
Solution Approach 1:
By combining multiple anchor components into a single integrated threaded fastener with alternating high and low threads, the patent enables installation using simple screw-driving tools rather than requiring multi-step assembly and expansion procedures, significantly reducing installation labor while maintaining holding strength in cracked concrete
4Ease of manufacture
If traditional thread formations are used, then manufacturing is simple, but penetration depth and concrete engagement are limited
Solution Approach 1:
The patent changes the thread formation parameters by introducing alternating high and low thread heights along the shank. This allows deeper penetration into cracked concrete while the low threads provide necessary spacing and concrete displacement, maintaining manufacturing simplicity through a continuous threaded formation rather than requiring complex multi-component assemblies
Data Source
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Figure 3~4
AI summary
A fastener for use in concrete includes a shank and a head. The shank has a tip distal most from the head. The shank includes a first helical thread formation having a thread form thereon formed from two portions disposed upon opposite lateral sides of the thread form. The thread form has a root and the two portions include an alternating series of lobe members and base portions. The lobe members have a height as measured from the root and the base portions have a height as measured from the root. The height of the lobe members is greater than the height of the base portions and the height of the base portions is greater than zero. The fastener includes a second helical thread formation that is disposed adjacent to and spaced from the first helical thread formation.