BBR Viscous Damper stay cable damping system

The BBR® Viscous Damper, specially developed to counteract vibrations on stay cables, works based on the resistance induced by the rapid passage of a viscous fluid through a narrow opening. The resistance can dissipate a large amount of energy leading to the damping of the cable. This principle of energy dissipation allows for an independent and real-time reaction of the damping device to the induced vibrations.

Internal damper configuration
External damper configuration

Cable vibrations

Despite the wide use of cable-stayed bridges, there are still several areas of great concern, especially the effects and elimination of cable vibration phenomena. Even newly constructed cable-stayed bridges have experienced quite severe vibrations. Several cable vibration mechanisms have been identified and characterized, with the four most common phenomena being vortex shedding, galloping, parametric excitation – bridge deck/pylon and cable interaction – and rain-wind induced vibrations.

Over the years, BBR has built an extensive knowledge of all these special stay cable phenomena, which has led to robust and reliable methods to counter such cable vibrations.

Damper configurations

The BBR Viscous Damper consists of twin hydraulic telescopic cylinders. The inner cylinder contains the piston chambers and the outer cylinder works as a housing and reservoir. The BBR Viscous Damper can be installed in either an internal or external damper configuration.

The BBR Viscous Damper (external) connects the stay cable directly to the bridge deck without the need of a large damper housing. It is equipped with a superior surface protection coating which protects it from the environment. The standard external viscous damper is a double acting device - extension and compression - and is available for a maximum damping force of up to 70kN. Larger damping force resistance is available upon request.

The BBR Viscous Damper (internal) is mounted inside a steel housing which gives support and protects against the environment. This compact solution is often preferred because it has a more aesthetically pleasing design. The standard internal viscous damper is also a double acting device and available for a maximum damping force of up to 50kN. Larger damping force resistance is available upon request.

Benefits of the BBR Viscous Damper

  • Free longitudinal and rotational movement, important for long cables where temperature changes and deflections are critical
  • Easy inspection and low maintenance requirements
  • Superior surface corrosion protection coating protecting against the harshest environments
  • Available in either an internal or external damper configuration
  • Double acting viscous damper pistons
  • Standard damping force up to 50kN and 70kN for internal and external damper configurations respectively. Larger sizes upon request
  • Adaptable to fit on any size of the BBR HiAm CONA stay cable range

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