Dampers: a viscous technology for smooth, constant and durable damping
Due to their low damping capacity, cable are subject to rain and wind induced vibrations, which can affect their performance and durability. Dampers have therefore become a common additional component in cable systems.
Freyssinet generally offers standard dampers for cables longer than 80m, which are sufficient to meet the usual needs of medium and long span bridges. However, several damping strategies can be considered depending on the project and the type of bridge, the cable geometry and the local environment.
The typical damper assemblies are:
- Internal Elastomeric Dampers (IED)
- Internal Hydraulic Dampers (IHD)
- Internal Radial Dampers (IRD)
- External Hydraulic Dampers (EHD)
Most of our damping systems are based on a viscous principle specifically designed so that performance is not dependent on cable amplitudes or temperature, providing constant and smooth damping.
Viscous piston dampers have the advantage of being very versatile as their viscosity coefficient can be adjusted and their stroke can be adapted, with references ranging from 40 mm to 920 mm.
Why choose Freyssinet stay cable dampers for your project
01. Versatility
Standard range of viscous piston dampers to suit any project need, from 20 kN/s/m up to 500 kN/s/m and strokes from 20mm up to 900mm+
02. High performance
Up to 6% damping and more
03. Proven track-record
Used, tested and proven on the longest cables in harsh environments, up to 600m
04. Durability
Endurance and fatigue tested over millions of cycles
05. Low maintenance
Dampers with play-free connections
06. Custom models
Design service available to create a damper specifically adapted to your project specifications
07. Full service
Modeling capabilities to help you define your needs
Internal Elastomeric Damper (IED)
Vibration energy is dissipated by shearing in a highly damping rubber. The internal elastomeric damper has a diabolo shape designed to maximize the sheared area as the cable moves, regardless of the movement direction.
IED technology is applicable to both new and existing structures. It is suitable for all types of stay cable systems and structures. It is particularly suitable for stay cables of less than 80 meters in length and footbridges.
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Invisible system, fully integrated into the guide tube
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Low maintenance
- No exposure to potentially aggressive environment
- No moving mechanic parts -
Removable and replaceable
Internal Elastomeric Damper (IED)
Vibration energy is dissipated by shearing in a highly damping rubber. The internal elastomeric damper has a diabolo shape designed to maximize the sheared area as the cable moves, regardless of the movement direction.
IED technology is applicable to both new and existing structures. It is suitable for all types of stay cable systems and structures. It is particularly suitable for stay cables of less than 80 meters in length and footbridges.
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Invisible system, fully integrated into the guide tube
-
Low maintenance
- No exposure to potentially aggressive environment
- No moving mechanic parts -
Removable and replaceable
Internal Elastomeric Damper specifications
Internal Hydraulic Damper (IHD)
The internal hydraulic damper is ring-shape and works by viscous flow to absorb the energy of the stay cable. It operates as a “jack” fixed onto the strands by means of a metal compaction collar and connected to the structure by a metal piston.
The damper is placed inside a metal tube called a guide tube. The guide tube is bolted to the formwork tube, which allows the eccentricity of the cable to be corrected.
Inside the ring cylinder, a silicone oil with optimized viscosity provides the required damping, depending on the characteristics of the cable stay. It is suitable for cable-stayed bridges or footbridges.
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Effective damping, even for very small oscillations
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System fully integrated into the guide tube:
-No impact on aesthetics
-No exposure to aggressive environment -
Easily accessible, removable and replaceable
Internal Hydraulic Damper (IHD)
The internal hydraulic damper is ring-shape and works by viscous flow to absorb the energy of the stay cable. It operates as a “jack” fixed onto the strands by means of a metal compaction collar and connected to the structure by a metal piston.
The damper is placed inside a metal tube called a guide tube. The guide tube is bolted to the formwork tube, which allows the eccentricity of the cable to be corrected.
Inside the ring cylinder, a silicone oil with optimized viscosity provides the required damping, depending on the characteristics of the cable stay. It is suitable for cable-stayed bridges or footbridges.
-
Effective damping, even for very small oscillations
-
System fully integrated into the guide tube:
-No impact on aesthetics
-No exposure to aggressive environment -
Easily accessible, removable and replaceable
Internal Hydraulic Damper specifications
Internal Radial Damper (IRD)
The internal radial damper consists of three hydraulic pistons placed at 120° angles around the cable. The inner end of the pistons is attached by pin joints to a collar that clamps the strand bundle. The outer end of the pistons is attached by pin joints to a metal tube called a guide tube. The guide tube is attached to the structure (formwork tube) by a bolted flange.
The efficiency of the system increases with the amplitude.
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Consistent performance in all temperatures
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High durability
Low maintenance
Protected from aggressive environment -
Removable and replaceable
Internal Radial Damper (IRD)
The internal radial damper consists of three hydraulic pistons placed at 120° angles around the cable. The inner end of the pistons is attached by pin joints to a collar that clamps the strand bundle. The outer end of the pistons is attached by pin joints to a metal tube called a guide tube. The guide tube is attached to the structure (formwork tube) by a bolted flange.
The efficiency of the system increases with the amplitude.
-
Consistent performance in all temperatures
-
High durability
Low maintenance
Protected from aggressive environment -
Removable and replaceable
Internal Radial Damper specifications
External Hydraulic Damper (EHD)
The external hydraulic damper consists of a rigid steel structure mounted with hydraulic pistons around the collar that clamps the cables clamping collar. As the damping efficiency increases with the distance between the damper and the anchorage, the external damper is used when the length of the guide tube and the elastic stiffness deteriorate the optimum damping.
These dampers are designed on a case-by-case basis according to the structural requirements of the cable-stayed bridge.
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High efficiency: the location is adapted to
the cable length, the vibration nodes and anti-nodes -
Consistent performance in all temperatures
(hydraulic piston technology) -
Easy to control and maintain
Low maintenance
Removable and replaceable
External Hydraulic Damper (EHD)
The external hydraulic damper consists of a rigid steel structure mounted with hydraulic pistons around the collar that clamps the cables clamping collar. As the damping efficiency increases with the distance between the damper and the anchorage, the external damper is used when the length of the guide tube and the elastic stiffness deteriorate the optimum damping.
These dampers are designed on a case-by-case basis according to the structural requirements of the cable-stayed bridge.
-
High efficiency: the location is adapted to
the cable length, the vibration nodes and anti-nodes -
Consistent performance in all temperatures
(hydraulic piston technology) -
Easy to control and maintain
Low maintenance
Removable and replaceable
External Hydraulic Damper specifications
HDPE main duct (high-density polyethylene)
Double spiral thread ducts are available to disturb the flow of water along the cable and thus limit rain and wind induced vibrations.
Applications: cable-stayed bridges, arch bridges, extradosed bridges.
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Rain and wind induced vibration control
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Transverse wind force on the stay cables
reduced by 20% with the super compact system
HDPE main duct (high-density polyethylene)
Double spiral thread ducts are available to disturb the flow of water along the cable and thus limit rain and wind induced vibrations.
Applications: cable-stayed bridges, arch bridges, extradosed bridges.
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Rain and wind induced vibration control
-
Transverse wind force on the stay cables
reduced by 20% with the super compact system
HDPE main duct specifications
A range of compact and super-compact stay cables with smaller diameters is also available to reduce the stay cable drag force.
Cross ties
Due to their flexibility, small mass and low damping capacity, stay cables are sensitive to high amplitude vibrations caused by wind, rain and movement of the supports. In addition to the usual devices, the use of customized cross ties can be recommended for longer cables, in order to increase the damping ratio of the vibrations compared to the standard values.
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Effective dissipation capacity
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De-correlation of the vibration frequency of the stay cables
from the natural / modal frequencies of the structure -
Improved in-plane stiffness of the stay cables
Additional damping capacity thanks to cross-ties
Cross ties
Due to their flexibility, small mass and low damping capacity, stay cables are sensitive to high amplitude vibrations caused by wind, rain and movement of the supports. In addition to the usual devices, the use of customized cross ties can be recommended for longer cables, in order to increase the damping ratio of the vibrations compared to the standard values.
-
Effective dissipation capacity
-
De-correlation of the vibration frequency of the stay cables
from the natural / modal frequencies of the structure -
Improved in-plane stiffness of the stay cables
Additional damping capacity thanks to cross-ties
Download our technical datasheets on our Damping systems
DocumentationGeoga bridge, South Korea / External Hydraulic Dampers
Geoga bridge, South Korea / Internal Radial Dampers
Golden Horn bridge, Russia
Millau Viaduct, France / Internal Hydraulic Dampers
Oresund bridge, Sweden / Internal Radial Dampers
Russky bridge, Russia / Damper collar
Russky bridge, Russia / External Hydraulic Dampers
Russky bridge, Russia / Internal Radial Dampers
Terenez Bridge, France / Internal Hydraulic Dampers
Geoga bridge, South Korea / External Hydraulic Dampers
Find our more in our case studies
Build
South Korea
Located in an exposed offshore area subject to high-speed winds and to potential typhoons, the cable-stayed bridge had to be equipped with the most robust cable anti-vibration system and durable stay cables.
Build
France
The unique launching procedure that was employed to build the deck of France’s prestigious Millau Viaduct put construction and cable-stay technology to the test.
Other cable system solutions
Strand solutions
Strands are the main components of Freyssinet Parallel Strand System (PSS) cables, and are often referred to as main tensile elements. They are the modular elements that allow full cables of any size to be made from lightweight yet durable elements bundled together. Freyssinet has developed two technologies, known as Monostrand® and Cohestrand®, which set the standard in the construction of cable structures.
Anchorage solutions
Anchorages are engineered by Freyssinet internal design team to extend the life of stay cables.
They are also manufactured in-house to ensure the highest level of manufacturing control.
Our modular solutions cover all needs from short cable hangers using clevis up to very long span cables.
Cable protection solutions
In addition to the risks associated with the construction of a bridge, owners must consider the risks throughout the life of the bridge, such as fire, lightning, explosion or ice formation on cables.
We have developed specific solutions for those of you who wish to better control these risks and limit or avoid the closure of a bridge and its impact on the local economy.
Aesthetic enhancement solutions
Cable-stayed bridges are elegant and strong structures that can become iconic architectural landmarks. To further enhance their aesthetics, we have developed coloured ducts and lighting systems. Combining functionality, aesthetics and mechanical performance, our solutions are customised to your requirements.
Suspension cable solutions
The parallel strand system developed by Freyssinet, well known for cable-stayed bridges and extradosed bridges, brings advantages in terms of durability for suspension bridges and cabled stadium roofs.
Cable systems
Cabled bridges and structures are sustainable, environmentally friendly and architecturally outstanding structures.
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