DYWIDAG Jacks Used for Launching of Athabasca River Bridge, Alberta, Canada

A new bridge has been built across the Athabasca River in Fort McMurray as a part of the ongoing expansion of Athabasca oil and sand developments. The new bridge runs parallel to two existing bridges and doubles the capacity of Highway 63 at its crossing of the Athabasca River.

The superstructure of the 472m long, 30m wide multi-span bridge consists of ten steel plate girders with a composite cast in place concrete deck. Launching all ten girders simultaneously proved to be the most economical solution and offered a schedule advantage. With the total weight of structural steel exceeding 6,000t, this segmental launch was one of the heaviest steel bridge launches ever undertaken in North America.

Detailed planning and design was necessary for aspects of the launch such as the launch nose, launch pad, girder supports, and the pushing assembly. DSI Canada supplied the launching equipment, hydraulic jacks including accessories and the anchorages for this project. During the launch, girders cantilevered the maximum clear span of 76m without the use of temporary supports. An inclined launch nose attached to the leading segment of girders made touch down at the piers. Of the total bridge span, 394m were launched, while the remaining 78m long section was crane-erected.

Lateral guides were positioned at the abutment and at each pier in order to maintain the longitudinal alignment of the girders. At the rear of each girder, a steel sled beam was used for vertical support and to facilitate longitudinal movement. A total of 10 strand jacks were fastened to the rear of the steel sled beams, all of which were simultaneously operated by a single hydraulic power pack. High strength strands were anchored at the abutment and ran along the length of the H-pile through the strand jacks.

During the post-tensioning operation, the jacks gripped the strands, which enabled the longitudinal launch. Each girder sled was tied together with a transverse push beam, which transferred the longitudinal pushing force from the sled beams to the girders. Just before completion, the maximum strand jack force was approximately 4,600kN (10,000,000lbs). The launch was successfully completed on schedule.