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The BBR Carbon Stay anchorages are the youngest member of the BBR stay cable family. Their exceptional high fatigue strength - up to 10 million load cycles with 250 N/mm2 - combines with light weight, corrosion-free properties. These characteristics make the system highly suitable for bridges with high traffic loads and for structures in corrosive environments, such as offshore platforms, or in industrial zones.
These relatively new cables offer significant advantages in three key areas:
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Bridge Construction
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Antennae & Stadium Roofs
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Maritime Construction
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- Suspender cables - high fatigue strength and corrosion-free properties suited for use in aggressive maritime or industrial environments
- Stay cables for footbridges - lightweight construction
- Larger spans for suspension bridges - impossible to achieve with steel
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- Carbon guys - low conductivity means no interference with electromagnetic fields
- Handling and maintenance - ease of handling and low maintenance
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- Tie-downs of offshore platforms, floating bridges & submarine tunnels - high fatigue strength and corrosion-free properties
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BBR Carbon Stay anchorages consist of up to 241 CFRP (Carbon Fibre Reinforced Polymer) wires of 5mm diameter and a corresponding load-carrying capacity of 12,000 kN. Its breaking load is up to 90% of the total wire capacity.
Relatively poor lateral properties of the CFRP wires, including interlaminar shear, meant that this high capacity could only be obtained by developing a suitable anchoring system. Therefore, EMPA (Swiss Federal Laboratories for Materials Testing & Research), in collaboration with BBR, developed a system - similar to the BBR HiAm anchorage - consisting of an anchor sleeve with conical inner boring, filled with graded layers of ceramic granules and polymer resin. No grouting is required because the BBR Carbon Stay system is corrosion-free.
In order to protect the wires against wind erosion and UV radiation, a polyethylene or similar sheath is adequate for shielding.
The installation and stressing procedure for all Stay Cable Systems depends on whether the stay cable is pre-assembled and transported to the construction site as a complete unit or whether it is assembled on site.
Life-cycle costing takes into account the predicted inspection and maintenance costs over the lifetime of a bridge - usually 100 years. Costs are evaluated by calculating the Net Present Value of the expenditure stream using a cash discount rate, typically of 6%.
Using this approach, CRFP is the material best-suited for suspenders and stay cables - based on the cost-effectiveness of the finished and installed product - as compared to the life expectancy and cost of the alternatives.
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