BBR Carbon stay cable technology
The patented BBR® Carbon stays have an exceptional high fatigue strength combined with light weight, corrosion-free properties. This makes the system highly suitable for bridges with high traffic loads and for structures in corrosive environments, such as offshore platforms, or in industrial zones. BBR installed carbon stay cables for the Storchen Bridge in Switzerland - the world's first bridge to feature carbon stay cables.
A first in carbon technology
As early as 1996, BBR installed carbon stay cables for the Storchenbrücke bridge in Switzerland - the world's first bridge to feature carbon stay cables. Its high fatigue resistance, light weight and corrosion-free 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.
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.
BBR, in collaboration with EMPA (Swiss Federal Laboratories for Materials Testing & Research), developed an anchorage system 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.
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.
CFRP stays application
BBR Carbon stay cables were developed in 1994 and the first application was in April 1996, on the twin-span cable stayed Storchen bridge in Winterthur, Switzerland. BBR Carbon Stay cables were installed alongside traditional BBR DINA parallel wire cables. Monitoring shows excellent results. An interesting phenomenon has been observed between the two stay systems – unlike in steel tendons, the thermal expansion of CFRP stays is almost zero. Therefore, a seasonal variation of the cable force can clearly be observed.