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May 9, 2014
PUBLIC WORKS: BRIDGES/RENOVATIONS
Owner/developer: Washington State Department of Transportation
Project team: Franklin Pacific Construction Co., general contractor; WSDOT, architect and structural engineer; Concrete Technology Corp., concrete contractor; Hood River Sand, Gravel & Ready-Mix, ready-mix supplier
The Satus Creek Bridge is located in Yakima County 25 miles southwest from Toppenish along U.S. Highway 97 at Satus Creek. It was built as part of a $13.4 million project completed in 2013.
The 180-foot-long simple-span bridge replaced an old, load-restricted timber bridge built in 1942. The new structure corrects design deficiencies with the old timber bridge, including vehicular impact and seismic resistance.
Several unique features were incorporated into the design, including horizontally curved and spliced precast girders.
A long, single-span bridge was necessary to satisfy environmental constraints related to crossing the wide creek. The bridge deck is conventional cast-in-place concrete. The shallow foundation also consists of conventional cast-in-place concrete.
The superstructure is composed of open precast concrete box girders, or “tubs,” which are horizontally curved and tipped to match the 8 percent cross slope of the bridge. To achieve this long, simple span across Satus Creek, each girder line consists of three precast girder tub segments.
Falsework towers were used to temporarily support the segments while the deck was cast and splice sections were assembled. Each tub web has three post-tensioning tendons. After post-tensioning was applied the temporary falsework towers were removed.
Composite provided the ability to have an increased span capability, eliminating the need for an intermediate pier. This was a great cost savings and it satisfied the environmental constraints.
Another added benefit that came with the spliced girders concept is the reduced shipping costs. The segments are easier to handle and more shipping routes become available to the girder fabricator at the time of delivery due to shorter and lighter girders.
The Satus Creek Bridge is the first horizontally curved precast post-tensioned girder bridge to be built in the state of Washington. It is a cost-effective, durable and resilient structure that is pleasing to the eye and satisfies the geometric and environmental constraints of the site.
The bridge was a testing ground for the state Department of Transportation’s Bridge and Structures Office. The team did not encounter significant issues during the design and construction phases of the project, but several design issues could present challenges for projects requiring smaller horizontal curvatures.