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Concrete Arches

Situation:

Interstate 5 is one of the busiest highways in North America, connecting all major urban centers on the West Coast and Canada to Mexico. In 2002 shear cracks were identified in the forty-year-old Interstate 5 bridges across the Willamette River dividing Eugene and Springfield, Oregon. Temporary bridges were quickly built to keep traffic moving but a more permanent solution was needed. The State of Oregon invested over $200 million to construct a long term, environmentally friendly and aesthetically pleasing solution. SPX Power Team participated in this effort, contributing powerful hydraulic cylinders in an application that demanded power and reliability in a compact package.

General Contractor for the project, Hamilton Construction of Springfield, Oregon, selected Precision Hydraulics LLC of Portland, Oregon, to assist with a key phase in this construction project.

Challenge:

Two arch ribs were constructed to create an arch span. Two arch spans were required to cross the Willamette River and these were cast in place. To replace both the northbound and southbound temporary bridges, nine spans were constructed across the river for a total of eighteen arches. Each arch was constructed on a temporary wooden superstructure, known as falseworks. Once the concrete was poured and cured, two challenges faced the construction team: how to load the ribs safely and how to remove the wooden falseworks. This project required the hydraulic equipment used in this application be load tested and certified to State of Oregon specifications.

Solution:

SPX Power Team provided the muscle, Precision Hydraulics provided the solution, and the University of Washington performed the load testing and certification. Together, SPX Power Team and Precision Hydraulics created a powerful, compact hydraulic ram designed to serve two purposes: lift the concrete arches off of the wooden falseworks while tensioning or “loading” each arch. The hydraulic system, consisting of cylinders, pumps and gauges were assembled, serialized, packed up and delivered by Precision Hydraulics to the University of Washington for load testing and certification.

Each arch consisted of two concrete arch ribs that were designed to meet at the top of the arch. At the very top of each arch a keystone area was left open in between these two concrete sections. A powerful but compact Power Team hydraulic ram was positioned into this vacant space. The heart of this ram was a 965 ton hydraulic cylinder with a 6" stroke. “Power Team cylinders were the only choice for this application because they combine tremendous lifting power in a small package, and this was a tight space we were working in. They’re rugged and dependable and have proven themselves,” said Precision Hydraulics’ Dave Rogers.

Process:

Standing 60 feet above the roaring Willamette River, the Power Team ram was used to apply pressure to the two arch ribs forming each arch. By pushing against each other, the two halves of the arch lifted up. By carefully coordinating this lifting action, Hamilton Construction was able to lift the entire concrete arch 1-1/2" to 2" in 3/8" increments, enough to clear the falseworks completely. With the lift successful and the concrete arch clear of the wooden falseworks, concrete was poured to fill this “keystone” space, completing each arch. The arch span was properly “loaded” and no longer resting on the falseworks, and the construction crew was able to disassemble and remove the wooden structure.

Result:

All nine spans have been constructed across the Willamette River. The southbound bridge was completed and opened for traffic in the summer of 2011, ahead of schedule. The northbound bridge is currently scheduled for completion in 2013. These two new bridges dividing Springfield and Eugene, Oregon enable Interstate 5 to connect Mexico to Canada and all the major population centers along the West Coast of the United States.