Movable Hanger for Cable-Stayed Bridge Stay Cable Replacement
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Solution Overview
Problem
The existing methods for replacing stay cables in cable-stayed bridges are complex and require multiple facilities due to the sag of stay cables when another cable is hung in tension, necessitating two-step pulling operations with a tower crane.
Innovation Solution
The use of movable temporary hangers placed on the stay cable above the target cable to hold and detach it from the bridge deck and main tower, reducing sag and simplifying the removal and installation process by guiding them with a pulling wire, and employing rollers to smoothly move and secure the cables without damaging the covering material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If another stay cable is hung in tension above the target stay cable during replacement, then the target stay cable experiences large sag, but this requires two-step pulling operations and increases facility complexity
Solution Approach 1:
A movable hanger is introduced as an intermediary device that travels along the upper stay cable (which is hung in tension) to hold and manipulate the target stay cable. This mediator enables the replacement operation without requiring the heavy tower crane facilities, thus reducing facility complexity while maintaining replacement reliability
Solution Approach 2:
The hanger is designed to be movable along the upper stay cable rather than fixed. This dynamic capability allows the hanger to position itself at different locations along the cable span, enabling flexible manipulation of the target stay cable and eliminating the need for complex fixed facility arrangements
2Reliability
If another stay cable is hung in tension above the target stay cable, then the target stay cable has large sag, but this increases the amount of pulling required and operation time
Solution Approach 1:
The movable hanger acts as a mediator that directly engages with the target stay cable and provides controlled lifting and positioning. This eliminates the need for lengthy two-step pulling operations through PC strands and tension rods, significantly reducing the time required for replacement while ensuring reliable cable installation
Solution Approach 2:
The invention skips the traditional two-step pulling process by using the movable hanger to directly position and secure the target stay cable in a single operation. This rushes through the replacement process more efficiently, reducing operation time while maintaining reliability
3Ease of operation
If traditional two-step pulling method is used with PC strand and tension rod, then the stay cable can be pulled into position, but this increases the number of facilities and pulling operation complexity
Solution Approach 1:
The movable hanger is a multi-functional device that combines the functions of holding, lifting, and positioning the target stay cable. It travels along the upper cable and performs multiple operations with a single device, eliminating the need for separate PC strands, tension rods, and associated facilities, thus simplifying the pulling operation
Solution Approach 2:
The invention merges multiple facilities (PC strand, tension rod, pulling mechanisms) into a single integrated movable hanger system. This consolidation reduces the number of facilities required and simplifies the pulling operation while maintaining the ability to effectively position the stay cable
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 method allows for efficient removal and installation of stay cables with reduced sag and fewer facilities, eliminating the need for primary and secondary pulling operations, thus simplifying the process and minimizing equipment requirements.
Implementation Method 1
employing rollers to smoothly move and secure the cables without damaging the covering material
Data Source
AI summary
A plurality of movable temporary hangers 7 are placed on a stay cable 4B hung in tension above a target stay cable 4C, and then the target stay cable 4C is held on a lower portion of the temporary hangers 7. Then, the target stay cable 4C held with the temporary hanger 7 is detached from a bridge deck 3 and a main tower 2. Then, the target stay cable 4C and the temporary hangers 7 holding the target stay cable 4C are moved toward the bridge deck 3 and removed.