Segmented Net Cloth Damping for Sea-Crossing Bridge Flutter
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Solution Overview
Problem
Traditional flutter control measures for long-span sea-crossing bridges are costly, cumbersome, and inefficient due to the need for large, heavy dangling plates that increase project costs and pose safety hazards, with inadequate energy consumption and control efficiency.
Innovation Solution
A dangling net cloth device suspended below the bridge, equipped with balance weights, which utilizes self-weight, water drag, and buoyancy forces to suppress flutter by synchronizing movement with the girder's cycle, optimizing balance weights for efficient energy consumption and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-sized dangling plate is used to provide sufficient water drag force, then the flutter suppression effect is improved, but the device size increases and installation becomes inconvenient
Solution Approach 1:
The patent divides the large dangling plate into multiple smaller net cloth panels arranged in parallel. Each panel is independently suspended by cables from the bridge girder, creating a segmented structure that provides sufficient total drag area while maintaining manageable individual component sizes for easy installation and removal.
2Strength
If the thickness or size of the dangling plate is increased to ensure stiffness, then the structural strength is improved, but the project cost increases greatly
Solution Approach 1:
The patent replaces the rigid plate structure with flexible net cloth panels. These thin film structures provide sufficient drag area without requiring thickening or stiffening ribs, dramatically reducing material consumption and project cost while maintaining the necessary aerodynamic performance for flutter suppression.
3Quantity of substance
If the mass of the dangling plate is reduced to lower cost, then the project cost is reduced, but the sinking speed becomes too slow to synchronize with the girder's downward movement
Solution Approach 1:
The patent optimizes the mass parameters of the net cloth panels and cable system to achieve synchronous movement with the bridge girder. By carefully selecting the mass ratio between the damping device and the girder, and adjusting cable lengths and pretension forces, the system achieves coordinated motion that ensures effective energy dissipation during both upward and downward girder movements.
4Productivity
If balance weights are added to synchronize descending speed, then the control efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent incorporates balance weights into the cable suspension system of each net cloth panel. These counterweights are attached to the lower ends of the suspension cables, creating a balanced system that automatically synchronizes the descending speed of the net cloth with the bridge girder, ensuring continuous engagement and maximum control efficiency without complex additional mechanisms.
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 device effectively reduces flutter and enhances wind-resistant safety with simpler construction, lower costs, and higher control efficiency, while being easier to install and remove, thus improving the practicality and safety of bridge wind resistance.
Implementation Method 1
the balance weights are mainly used to accelerate the descending speed of the net cloth
Implementation Method 2
a drag force is produced when the device moves upward with the girder, which will do negative work on the girder to consume vibration energy
Implementation Method 3
when the girder moves downward, the dangling net cloth device moves downward under the action of gravity, buoyancy and water drag force
Data Source
AI summary
The present invention belongs to the technical field of wind-induced vibration control study of bridges, and provides a dangling net cloth device for suppressing flutter of a sea-crossing bridge, i.e., a large-area dangling net cloth equipped with multiple balance weights, which is suspended below a girder by ropes and is immersed in water. When wind-induced vibration occurs on a bridge, the device is driven to move in the water, and gravity of the device as well as a huge additional mass force and an additional damping force produced by the water on the net cloth will do negative work on the girder to consume vibration energy of the bridge and effectively suppress large vibration of the bridge. The device adopts lightweight standardized components which are convenient to install, detach, transport, and store, and has the advantages of safety, reliability, economy, and practicality.