Innovative CFRP Cables Used at Ränggloch Viaduct
At Carbo-Link, we are proud to have delivered a global innovation in structural engineering with the installation of CFRP prestressing cables featuring fully CFRP anchorages at the newly constructed Ränggloch retaining viaduct near Lucerne, Switzerland.
As part of a broader infrastructure upgrade to improve traffic safety and natural hazard protection, two conventional steel tendons in the end span of the seven-span structure were replaced with our high-performance CFRP parallel wire cables, each comprising 91 carbon wires and delivering a prestressing force of 2100 kN. This marks the first-ever application of a fully CFRP anchoring system in a bridge.
Key Contributions by Carbo-Link
Complete CFRP System: Both cable and anchorage are made entirely of CFRP, eliminating corrosion risk and significantly reducing weight. Just 2.75 kg per meter, despite the cable’s strength.
Custom-Engineered Solutions: Through extensive in-house testing, including curvature and transverse pressure validation, we enabled tight curvature radii of 7.6 m, previously considered problematic for anisotropic materials like CFRP.
Integrated Monitoring: Our unbonded cable design allows for direct force measurement using load cells, supporting long-term structural monitoring and data gathering, a key objective for this pilot installation.
Simplified Handling: Thanks to low weight and compact transport geometry (coiled in a figure-eight), the cables were easily delivered and installed on-site.
Anchorage Design: We developed and supplied lightweight conical CFRP anchor sleeves, manufactured via filament winding. These integrate with an epoxy-based force transfer system and stainless steel ring to distribute load across all wires.
Proven Performance: Static and long-term load testing conducted at Empa confirmed the outstanding performance of our system, with a mean failure load of 4.26 MN and minimal variation, highlighting the reliability of our CFRP technology.
Although reversibility was originally planned, it was ultimately deemed unnecessary given the robustness of the solution. The bridge remains accessible for future interventions if needed.
A Milestone for CFRP in Infrastructure
This project sets a new benchmark for the use of CFRP in prestressed concrete structures. We are excited to have contributed this pioneering technology to the Ränggloch viaduct and look forward to the insights that will be gained from long-term monitoring.
Project Partners
Client: Kanton Luzern – vif
Engineering: IG Kost + Partner / B + S
Contractor: Anliker Bauunternehmung
Key Participants: Carbo-Link, VSL Schweiz, Ganz Consulting
Read the full and original article in German here: Spannende Weltneuheit am Ränggloch
