T.Y. Lin International (TYLI) was selected as a subconsultant to perform the fatigue review and independent design check for the all-weather Deh Cho Bridge across the Mackenzie “Deh Cho” River in Northern Canada. The project was for the Government of the Northwest Territories in a Public Private Partnership (P3) with the Deh Cho Bridge Corporation.
Replacing seasonal ferry and ice road operations, the 1100-meter-long Deh Cho Bridge is nine-span deck truss structure with a cable-supported main span of 190 meters. The truss is a Warren truss with vertical members and composite with a precast, prestressed concrete deck. The bridge substructure includes eight piers, each consisting of a steel delta frame supported on a massive reinforced concrete pier base, in turn supported on a spread footing.
The layout for the Deh Cho Bridge is unusual for a cable-stayed bridge, in that the backstays terminate within the backspan, instead of at a pier. This arrangement has a major effect on the stress conditions imposed on the truss.
- TYLI developed a global model for the superstructure, towers, stay cables, and piers under both dead and live loads.
- A fatigue analysis of all steel details was successfully conducted on the bridge by developing local 3D models for critical superstructure truss assemblies, stay cable to deck connections, and other elements.
- Following the fatigue review, the TYLI team was asked to perform a complete design review of the stay cables, connections, superstructure truss members, and towers.