The mechanisms of dynamic excitation are complex and predictions are difficult. VSL has developed simulation tools to assist designers in assessing the risk of cable vibrations and in proposing suitable mitigation measures, for both new and existing bridges.
In addition to adapting VSL-designed stay pipe profiles to better control the risk of rain-wind induced vibrations, VSL has developed two damping devices that increase the structural damping of the cable.
- The VSL Friction Damper is the most efficient passive damper available for use on long-span stay cables requiring high damping levels.
- The VSL Rubber Damper is a modular passive damper designed for medium-span stay cables.
Both types can be installed either at construction stage or as a retrofit add-on.
VSL dampers’ outstanding durability is achieved by:
- minimizing the number of movable parts, which reduces the wear and tear;
- utilizing dissipation mechanisms that employ stable solid materials instead of fluids.
The damper configurations provide an easy access for inspection and maintenance. All components can be dismantled and/or replaced on site using light tools and equipment, with minimum impact on the bridge’s operation.
Both damper types are optimized for use as internal dampers, fully protected inside the VSL SSI 2000 anti-vandalism pipe, but they can also easily be adapted for retrofitting existing cables of any type or for use as external dampers if required.
The compact and highly-efficient nature of VSL dampers allow installation close to the deck anchorage, where they are incorporated into the SSI 2000 System as internal dampers, fully protected inside the anti-vandalism pipe.