Cable Bridging Collar Structure for High-Tension Slackening
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Solution Overview
Problem
Existing bridging devices for structural cables, such as stay and external prestressing cables, face challenges in securely relaxing high-tension cables due to friction issues with cementitious materials and structural instability, particularly when cables are under high tension or have smoother reinforcements, leading to potential slippage and mechanical stress.
Innovation Solution
A bridging device with adjustable clamping collars and a fluid wedging material system that allows for precise tension management and improved interface quality, featuring monobloc half-collars with integrated longitudinal reinforcements and anchorages to reduce bending forces and enhance robustness, along with a compact design for easier installation and redundancy in traction elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sufficient transverse tightening is applied to prevent slippage of cable collars, then friction and shear at interfaces are improved, but the cementitious material degrades and interface quality deteriorates
Solution Approach 1:
The patent introduces a steel collar as an intermediary component between the reinforcement bars and the cable. The collar transfers forces through direct contact with the bars rather than relying on friction through degraded cementitious material. This mediator prevents slippage through mechanical interlocking and direct force transmission, eliminating the need for high transverse tightening that causes cementitious material degradation.
2Strength
If external prestressing cables are tensioned to high levels (80% capacity), then structural performance is improved, but the risk of slippage between reinforcement and cementitious material increases
Solution Approach 1:
The steel collar acts as a reliable intermediary that maintains force transmission integrity even under high tension conditions (80% capacity). Instead of relying on the cementitious material interface which becomes unreliable at high tensions, the collar provides direct mechanical contact with the reinforcement bars, ensuring consistent force transfer regardless of the tension level.
3Ease of manufacture
If smoother reinforcement bars are used, then manufacturing and installation are easier, but the risk of slippage between reinforcement and cementitious material increases
Solution Approach 1:
The steel collar serves as a mediator that compensates for the reduced friction of smoother reinforcement bars. Instead of relying on surface friction between rough bars and cementitious material, the collar provides mechanical interlocking and direct force transmission through contact with the smooth bars, maintaining reliability while allowing easier fabrication and installation of the reinforcement.
4Reliability
If a permanent sleeve system with yoke-shaped structures is used for bridging, then cable tension can be relieved, but the device becomes bulky and difficult to install in certain configurations
Solution Approach 1:
The bridging device is segmented into separate components: a collar that fits around the cable and a separate yoke-shaped structure that provides axial support. This segmentation allows the collar to be installed directly on the cable in confined spaces, while the yoke structure can be positioned and connected afterward. The modular approach enables installation in tight configurations where a single integrated bulky device would not fit.
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 solution enables secure relaxation and cutting of high-tension structural cables by providing increased clamping force, improved interface quality, and enhanced safety against slippage, suitable for various cable types, including external prestressing cables, with a more compact and robust design that reduces mechanical stress and facilitates easier installation.
Implementation Method 1
at least one injection orifice for shim material in a space extending between each tie and the cable before tightening the tie
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A bridging system for locally slackening a structural cable (C) before its sectioning, comprising a bridging device (1) including: - Two clamps (10) to be placed on said cable, each clamp (10) being formed of two half-clamps (11) suitable for positioning around the cable, each half-clamp (11) being elongated along the longitudinal axis of the cable and made with a body (14) defining a substantially hemispherical cavity, - tensioning elements (21) extending between the clamps (10), - means for adjusting (31, 26, 27) the tensile force transmitted through the tensioning elements (21), a system characterized in that each of at least two half-clamps (11) comprises, as a single unit with it: ∘ longitudinal reinforcements (17) extending along said body (14) over at least a portion of its length, ∘ anchorages (23) extending between these longitudinal reinforcements (17) and ∘ anchorages (29,34) located in the axial continuity of the longitudinal reinforcements (17), the transmission of the force from the tensile elements (21) to the collars (10) taking place via said anchorages (23, 29, 34).