BBR Square Damper stay cable damping system
Due to its simple design, high efficiency, easy adjustability and low maintenance requirements, the BBR® Square Damper is simply the most superior damping device available on the international market. The BBR Square Damper incorporates a new generation of materials, together with a ventilation/insulation system to enhance the durability of the components and to extend maintenance intervals.
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 – 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.
The BBR Square Damper is a superior supplemental passive damping device, which is based on friction. This device can be used as an internal damper, where it is installed inside the steel guide pipe or alternatively as an external damper, attached to the cable free length using a damper housing and external brace. The damper has been proven, by testing, to achieve the Maximum Passive Supplemental Damping considered for a ‘perfect damper’.
The BBR Square Damper also comes with an optional mechanical stop in situations with high cable deformations and/or rotations.
Benefits of the BBR Square Damper
- Friction damper with uniform friction properties
- Damper not activated at low/non-critical vibration amplitudes
- Free longitudinal and rotational movement, important for long cables where temperature changes and deflections are critical
- Easy inspection and extremely low maintenance
- Easy adjustability at any time to match working amplitudes
- Efficiency independent of acceleration/mode of vibration
- Damping efficiency proven by testing
- High endurance and constant performance
- Proven to work on existing projects
New generation of materials
The development of the BBR Square Damper has included, among others, several multi-million cycles of full damper oscillation wear tests to establish the actual endurance of the friction components. During the tests the temperature was deliberately kept constantly high (T > 300°C) to promote wear and damage. Such tests proved that only a new generation of friction materials, especially designed for the severity of this application, can be used.