UHPC Resin Bridging for Prestressing Cable Tension Transfer
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Solution Overview
Problem
Current methods for maintaining prestressing cables in engineering structures, such as bridges, are inefficient due to the need for extensive surface preparation, potential dynamic effects during cable removal, and the requirement for precise jaw adjustments, which can be time-consuming and risky, especially when dealing with localized corrosion issues.
Innovation Solution
A method involving the use of prestressing bars positioned parallel to the cable, surrounded by a formwork volume filled with UHPC fiber-reinforced concrete or resin, which mechanically confines the volume and transfers forces by adhesion, allowing for gentle tension recovery without the need for jaw installation and enabling the preservation of the cable without removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional jaw clamps are used to secure the cable, then the cable can be temporarily secured, but extensive surface preparation is required which increases operator exposure time to fracture zones
Solution Approach 1:
The patent introduces an intermediary material (grout or resin) that bonds the cable to the surrounding concrete structure, eliminating the need for direct mechanical attachment with jaws. This intermediary bonding mechanism transfers forces through adhesion rather than requiring surface preparation and mechanical clamping, thereby reducing operator exposure time while maintaining cable security.
Solution Approach 2:
The patent replaces the mechanical jaw clamp system with a chemical bonding system using grout or resin. Instead of relying on friction and mechanical interlocking that require extensive surface preparation, the system uses adhesive bonding to secure the cable, significantly reducing the time operators need to spend in hazardous zones.
2Reliability
If jaw clamps are used to transfer tension, then the cable can be secured, but the system requires precise adjustment to the precise cable type which delays emergency response
Solution Approach 1:
The grout or resin bonding system is universally applicable to different cable types without requiring precise adjustment or customization. The material adapts to various cable geometries and types, eliminating the need for studies, method development, and manufacturing processes required for conventional jaw clamps, thereby enabling faster emergency response.
Solution Approach 2:
The bonding properties of the grout or resin can be adjusted through material composition changes rather than mechanical adjustment, allowing the same system to work with different cable types and geometries without requiring customization or precise tuning, thus accelerating emergency repair deployment.
3Reliability
If the cable is injected into cement grout, then the elastic energy can be contained, but considerable dynamic effects and potential damage to the structure can occur upon cable failure
Solution Approach 1:
The patent uses composite material systems where the cable is bonded to the concrete structure through grout or resin, creating a composite action that distributes stress more evenly. This composite bonding mechanism reduces the sudden release of elastic energy and minimizes dynamic effects compared to direct cement grout injection, thereby protecting the structure from damage upon cable failure.
4Reliability
If conventional nailing force is applied to bolts, then the cable can be secured, but the system requires monitoring or control measures to maintain nailing force which increases system complexity
Solution Approach 1:
The grout or resin bonding system is self-service in that it automatically maintains the bonding force through its adhesive properties without requiring external monitoring or control measures. The material inherently resists debonding and maintains cable security without the need for active force management systems, thereby reducing device complexity.
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
This solution reduces the bulk and complexity of installation, allows for the conservation of the prestressing cable by adhesion rather than nailing, and provides a durable, low-maintenance system adaptable to various cable types and geometries, minimizing exposure risks and maintenance time.
Implementation Method 1
ensuring the transfer by adhesion of the forces initially suffered by the cable
Implementation Method 2
to mechanically confine said volume then filled with UHPC or resin
Implementation Method 3
to tension the prestressing bars
Data Source
Figure 1~2
Figure 3~5
Figure 6~8
AI summary
This method for the local tensioning of a prestressing cable (2) of a structure, for the purpose of its removal or preservation, consists of: ▪ positioning by means of shims at least two prestressing bars (5, 6) on either side of the cable in question, said prestressing bars extending substantially parallel to said cable at the level of the tensioning zone, i.e. the zone of fragility of said cable, and this upstream and downstream of said zone; ▪ encasing the assembly consisting of the cable (2) and the prestressing bars (5, 6) upstream and/or downstream of the tensioning zone, and over at least part of the tensioning zone, defining a volume substantially centered around the cable; ▪ injecting, into said volume, UHPC (ultra-high performance fiber-reinforced concrete) or a resin of equivalent characteristics, filling the entire volume; ▪ to mechanically confine said volume then filled by the UHPC fiber-reinforced concrete or resin;▪ to allow the concrete or resin to set; ▪ to put the prestressing bars (5, 6) under tension.