A well proven SSI stay-cable system
VSL stay-cable systems are made up of:
- Tensile elements that carry the load;
- Anchor components that transfer the loads to the structure;
- Cable encapsulation to provide protection against environmental factors, and manage the response to ice and wind;
- Deck-level protection against vandalism, fire and blast;
- Transition devices for control of vibration and deviation of the cable.
VSL SSI 2000 is the company’s well-proven and widely used state-of-the-art stay-cable system. It exceeds the highest standards of fatigue performance and includes a high level of corrosion protection.
SSI 2000 is also available as a compact version designed to limit the impact of wind: SSI 2000C has a smaller cable diameter that greatly reduces wind drag.
Why use SSI technology instead of PWS?
VSL uses SSI technology, meaning ‘strand by strand installation’: the light weight of the equipment – and the cables in particular – allows for extreme ease and flexibility of installation compared to systems with parallel wire strands (PWS).
SSI also allows for easy replacement of components throughout the entire lifecycle of the structure, without the need to dismantle the anchorages or the rest of the cable.
Stay-cable erection with the SSI system permits full control of operational risks.
Main tensile elements of stay-cable system
The VSL SSI system is highly modular and can therefore accommodate various types of strand:
- Galvanized, waxed and sheathed strand in accordance with fib or CIP standards;
- Waxed and sheathed strand in accordance with PTI standards;
- SSI 2000 is fully proven for use with ultra-high-grade strand (2200MPa)
- SSI 2000D, which meets fib standards, is the world’s most compact stay-cable system with active corrosion protection. Its permanent dehumidification unit provides a controlled environment that not only protects the steel strands from corrosion, but also allows for easy monitoring and inspection.
The anchorage is the most critical item of the stay cable. The anchorage must:
- always remain leak-tight;
- resist the cable deviation in order to limit the stresses on the strands;
- permit cable tension measurement and adjustment during the bridge’s operation;
- permit the exchange of strands if required for inspection or maintenance.
VSL has developed a wide portfolio of anchorages to provide an abundance of design flexibility:
- SSI 2000e DR and SSI 2000e DS have no limitations in their application: they are suitable for long-span cable-stayed structures. They provide high fatigue resistance. In situations where one or more strands need replacement, the VSL SSI 2000e anchorage allows the sealant system to be replaced strand by strand.
- MSI 2000e DR and MSI 2000e DS are heavy-duty articulated anchorages. They have been specifically engineered for the hangers of arch bridges and the stays of suspended roofs. Equipped with articulated forks, MSI anchorages still provide the same high fatigue resistance as the SSI 2000e anchorages.
- SSI 2000d DR and SSI 2000d DS are suitable for structures already protected by dehumidification.
- SSI Saddle, which has a minimum radius of 1.5m and no limitation on angles, is able to withstand differential forces at either side of a pylon thanks to friction between the strands and the saddle. This solution has the advantage of dramatically simplifying the pylon detailing and construction with no compromise on the mechanical and durability performance.
Specific solutions for cable protection
VSL has developed stay pipe profiles and specific solutions to mitigate risks from the accumulation of snow and ice and protect against fire and blast. They can even be equipped with a network of LEDs to turn bridges into visually iconic displays.
VSL has developed a portfolio of four transition components that allow for the control of loads arising from vibration and deviation:
- Tension rings compress the strand bundle – they are the default solution for top anchor points;
- Guide deviators compress and guide the strand bundle – they are required to avoid clashes between strands and guide pipes;
- High-damping rubber dampers provide stay-cable damping – they are used for the dynamic stability of medium to long cables;
- Friction dampers provide a higher degree of damping for long cables subjected to severe environments.