Spiral Wire Vibration Mitigation for Stay Cables
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing stay cables in structural works, especially those installed before the widespread use of shaped sheaths, experience significant vibrations due to the rain + wind phenomenon, which are costly and complex to mitigate using traditional methods like massive dampers or replacing smooth sheaths with shaped ones, affecting durability and watertightness.
Innovation Solution
Spirally winding one or more wires around the externally smooth sheath of the stay cable to disrupt water trickles and modify its aerodynamic behavior, improving stability without compromising watertightness or requiring extensive changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If massive dampers are installed on the stay cables to reduce vibrations, then vibration amplitude is reduced, but device complexity and cost increase
Solution Approach 1:
The patent applies this principle by wrapping a flexible wire around the stay cable to modify its external profile. The wire acts as a thin film that changes the aerodynamic characteristics of the cable surface, disrupting water flow patterns and reducing rain-wind induced vibrations without requiring massive dampers or complex mechanical systems.
2Object-affected harmful factors
If smooth sheaths are replaced with shaped sheaths to reduce vibrations, then vibration amplitude is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies segmentation by separating the sheath function from the vibration mitigation function. Instead of integrating the shaped profile into the sheath itself (which would require complex manufacturing), the solution uses a separate wire wrap that can be applied to standard smooth sheaths, simplifying manufacturing while achieving the same aerodynamic effect.
3Stability of the object's composition
If complete change of smooth sheaths to shaped sheaths is performed, then vibration stability is improved, but watertightness quality deteriorates
Solution Approach 1:
The flexible wire wrap serves as an external aerodynamic modification that does not compromise the integrity of the underlying smooth sheath. The wire is positioned externally and does not create penetration points or discontinuities in the sheath structure, thereby maintaining watertightness while providing vibration mitigation through aerodynamic profile modification.
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 significantly reduces vibration amplitudes by up to a factor of five, enhancing the stability of stay cables already in use, while being simpler and less costly than traditional solutions, without affecting the cable's quality or watertightness.
Implementation Method 1
The presence of those two trickles of water changes the aerodynamic behavior of the cable and the oscillatory movement of the top trickle generates aerodynamic forces which lead to instability of the stay cable
Implementation Method 2
Tests performed by the applicant with a double helix arrangement having the above mentioned dimensions in terms of pitch, thickness and a width have revealed a reduction of the amplitude of the vibrations resulting from the rain + wind phenomenon up to a factor five
Data Source
AI summary
The invention proposes a method for improving the stability against vibrations of a stay cable (12) comprising at least one strand (11 ) housed in a substantially externally smooth sheath (1). In this method, at least one wire (2- 3) is spirally wound round the sheath so as to be substantially in contact with said sheath along at least part of the stay cable.