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Damping systems for stays

State-of-the-art high-performance and durable damping solutions to mitigate vibrations induced by traffic or wind loadings on cable-stayed bridges

  • Incheon Bridge - Focus: Dampers
    First use of VSL Dampers in Asia.
    South Korea - 2009 read more

    Incheon Bridge - Focus: Dampers

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  • Sacavém Viaduct
    Repairs and seismic upgrades to a bridge over the Trancão River.
    Portugal - 2009 read more

    Sacavém Viaduct

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  • Penang Second Crossing
    Construction of a 24km bridge.
    Malaysia - 2010 read more

    Penang Second Crossing

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  • Lekki-Ikoyi Link Bridge
    VSL's Stay cable system and VSL R-dampers on Nigeria's first cable-stayed bridge.
    Nigeria - 2013 read more

    Lekki-Ikoyi Link Bridge

                     DOWNLOAD PROJECT REFERENCE(S)

State-of-the art-technology for the control of vibrations of stay cables

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Modern cable-stayed structures have to accommodate increased dynamic demands on their cables.

To address these requirements, VSL has developed vibration damping systems of high efficiency and extraordinary durability with low maintenance costs.

The two complementary systems are the VSL Friction Damper and the VSL R-damper.

A wide range of calculation tools is used by VSL when advising its clients on the most appropriate solution for a particular project, whether a new structure or the retrofitting of an existing one. VSL also supplies and installs the damping systems.

Stay cables are among the industry's most sophisticated technologies and so specialist expertise is the key to providing viable, economical and reliable solutions.

VSL has become a world-leading stay cable contractor and offers an extensive range of services ranging from design assistance through cable supply and installation to full bridge construction packages. This makes VSL an invaluable partner for any bridge contractor or bridge owner, in particular when it comes to addressing the specific challenges of cable-stayed bridges.

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VSL's products and services

For damping solutions, the services offered by VSL include:

  • Stability risk analysis
  • Proposal of mitigation measures, including provision of dampers
  • Modelling of the behaviour of the damper-equipped cables, taking into account excitation by aerodynamic effects and structural coupling. VSL uses calculation tools that have been developed in collaboration with internationally renowned experts in the industry.
  • Design, fabrication, workshop testing, supply and installation of a choice of two different damping systems - the VSL Friction Damper and the VSL R-damper
  • Full integration of the two different damper types into the VSL SSI 2000 stay cable system, either at the time of installation or for installation at a later stage (retrofitting)
  • Retrofitting solutions for existing strand and parallel wire cables
  • Fine-tuning of damping devices after installation to match the actual characteristics of the cables and structure

Associated services

Advantages of VSL's offer

Two systems cover the full range of requirements

The VSL Friction Damper is more suited for long cables while the VSL R-damper is more suited for cables of short or medium length. The choice allows the selection of the most suitable damping behaviour, taking account of the characteristics of an individual cable. In addition, the VSL R-damper is available in two grades - ‘Standard’ and ‘High Performance’.

Two systems with the same external appearance

The external components and shapes are identical for both systems, even though they adopt different approaches to dissipating the vibration energy. This allows a consistent appearance along a bridge, even where both systems are required.

Precise tailoring to meet damping requirements

For both dampers, the heart of the damping system is made up of modular dissipative elements that can be fully adapted to all cable sizes.

For VSL Friction Dampers, the performance can be fine-tuned after installation by adjusting the friction force without dismantling the damper.

For the VSL R-damper, the number of pads required is based on the dynamic characteristics of the cable. This allows easy adaptation to all cable sizes, whether for a new installation or as part of a retrofitting solution.

Highly efficient

Various comparative tests on full-scale cables have demonstrated the exceptional efficiency of the dampers. Their measured performance has repeatedly exceeded the specified requirements, as well as exceeding that of other types of dampers.

Very durable

Outstanding durability is achieved by a combination of a movable parts and making use of dissipation mechanisms that employ stable solid materials instead of fluids.

Fully integrated for enhanced aesthetics

The compact and highly efficient nature of the dampers allows installation close to the deck anchorage, where they are fully integrated into the anti-vandalism pipe.

This avoids them affecting the visual appearance of the stay cable.

Thanks to their identical cover designs, both types of damper can be installed easily on the same structure without introducing visual differences.

Easy maintenance

The damper configurations provide easy access for inspection and maintenance operations and use a minimal number of moving parts.

All components can be dismantled and/or replaced on site using light tools and equipment, with minimum impact on the bridge's operation.

Versatile

Both damper types are optimised for use as internal dampers, fully protected inside the VSL SSI 2000 anti-vandalism pipe, but they can also easily be adapted for retrofitting solutions or use as external dampers if required. They can be attached to both parallel strand systems (PSS) and parallel wire systems (PWS). They can be fitted on new structures or retrofitted to existing ones.

Contributing to sustainable solutions

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VSL's dampers have been designed and constructed as very durable systems. Moreover, their function in mitigating vibration reduces the risk of material fatigue in the stays and in the bridge, which in turn reduces the need for maintenance and replacement during the service life of the structure. They make a vital contribution to increasing the life expectancy of structures.

Stay cable vibrations - complex phenomena

Various effects can lead to excitation of the cable and eventually to instability of the structure if the vibrations are not controlled. Stay cables are generally excited by aerodynamic forces acting on the cable, or by anchorage displacements caused by the action on the structure of dynamic forces such as traffic.

Wind excitations can be categorised into four families:

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VSL dampers - high performance and outstanding efficiency

For both the VSL Friction Damper and the VSL R-damper, the heart of the damping system is a modular dissipative element that is fully adaptable to all cable sizes. It can be easily inspected and even upgraded if required using light tools and equipment, with minimum impact on bridge operation.

In addition, both damping systems are enclosed inside a robust anti-vandalism pipe if installed with the VSL's SSI 2000 stay cable system. The cover ensures full protection while giving a slender external appearance. Both damper types use identical cover designs and so can be installed on the same structure without any undesirable visual differences.

The VSL damper supports are integrated into the guide pipe that is part of the main structure to provide a stiff support for maximum performance.

Two complementary systems with similar features

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VSL FRICTION DAMPER

How it works
Dissipating energy through friction

The VSL Friction Damper applies the same principles used in disc brakes, by dissipating the energy through friction generated between two friction 'partners'. The first is a pair of sliding discs, connected via a collar to the tensile member of the stay. It is sandwiched by the second partner, which consists of a specially developed composite pad supported by a pair of spring blades connected to the external structure of the guide pipe.

Main components
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High performance and outstanding efficiency
Unaffected by temperature
Perfectly tuned for critical vibrations
Activated only when needed
The most efficient passive damping system
Easy installation and tuning
Dimensions

VSL R-DAMPER

How it works
Shear deformation of high-damping rubber
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The heart of the VSL R-damper is a high-damping rubber (HDR) material. It dissipates the kinetic energy of the vibration by shear deformation of specially designed pads. Each damper consists of a series of pads mounted between a moveable collar attached to the tensile element of the stay cable and a fixed support rigidly connected to the guide pipe.

The damper’s characteristics are adjusted for each structure by varying the number of pads and choosing between two pad types - high performance and standard. The HDR can withstand large shear deformations and can also cater for significant deformation under tension or compression without affecting its damping properties. This allows longitudinal movements between the cable and support to be accommodated entirely within the HDR, which avoids the need for additional hinged or sliding interfaces that would affect the damping ratio.

Main components
The VSL R-damper unit
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The VSL R-damper assembly for stay cable applications

Durability without maintenance
Independent of vibration mode and amplitude
Highly deformable

Both the VSL Friction Damper and the VSL R-damper are optimised for use as internal dampers, fully protected inside the VSL SSI 2000 anti-vandalism pipe.

They can also easily be adapted for retrofitting solutions or use as external dampers if required.

They can be attached to both parallel strand systems (PSS) and parallel wire systems (PWS).

Finally, they can be fitted on new structures or retrofitted to existing ones.

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Neva Twin Bridges in St Petersburg, Russia

Friction dampers : 224 units

Uddevalla Bridge, Sweden

Uddevalla Bridge, Sweden

Friction dampers : 120 units

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Incheon Bridge, Korea, 2009

R-damper : 16 units

Friction dampers : 192 units

With a main span of 800m, the Incheon Bridge has one of the longest cable-stayed spans in Korea. VSL provided an efficient damping system to protect the cables against unacceptable vibrations.

Puente de la Unidad, Mexico

Puente de la Unidad, Mexico

Friction dampers : 26 units

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Vancouver Bridge, Canada

R-dampers

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