ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/306885
Precast trapezoidal tub girder. The Selah Creek Fred G. Redmond Bridges on I-82 near Yakima opened in 1971. 46 | ASPIRE , Summer 2008 S TAT E C oncrete is the material of choice for the majority of bridges in the State of Washington. Approximately 2600 out of 3000 bridges maintained by the Washington State Department of Transportation (WSDOT) have a main span type that consists of concrete. The oldest of these bridges dates back to the early 1900s . The first known use of a precast, prestressed concrete girder bridge in Washington was in 1954 for a bridge over the Klickitat River on State Route 142. The center span of this three-span bridge is 90 ft and consists of four precast segments about 22 ft in length that were supported on falsework in place and then post-tensioned together. The contractor chose to install the girder in units, based on the lifting capacity of his crane. Technology and equipment have advanced since then to allow current bridges with spliced girders to have lengths in excess of 200 ft. There are two major statewide transportation improvement programs underway. The first, known as the "Nickel" funding package, began in Concrete Bridges in Washington State by Jugesh Kapur and DeWayne Wilson, Washington State Department of Transportation 2003 with a total budget of $3.9 billion to address primarily congestion and safety on 158 projects. The second, known as the "Transportation Partnership Account" began in 2005 with a total budget of $7.1 billion to address preservation and mobility on 274 projects. Concrete bridges will play a big part in these new programs. Selah Creek Arches The twin Selah Creek Fred G. Redmond Bridges on I-82 provide a connection south from Ellensburg to Yakima. They were the largest arch span bridges in the United States at 549.5 ft when they opened to traffic in 1971. The top of the arch span is 325 ft above the canyon and required falsework to be built from the valley below. The superstructure on each bridge consists of 17 spans of prestressed concrete girders that are 78.5 ft long. These two bridges are examples of the use of concrete for nearly 780 interstate bridges built between 1955 and 1975 that are now 30 to over 50 years old. South 317th St HOV Access In 2006, a bridge was opened over I-5 near Federal Way to provide direct access for buses and high occupancy vehicles from I-5. Bridge engineers decided to use precast, prestressed concrete trapezoidal tub girders 5 ft wide and 6 ft deep that were spliced together with post-tensioning. The bridge span is curved at the intersection with the access ramps to accommodate turning buses. The structure is 128 ft long with four spliced precast, trapezoidal tub girders, each consisting of 35-ft- and 88-ft-long segments. The segments were temporarily supported on falsework and then post-tensioned together. The bridge has 50-ft radius curves connecting to the ramp side. Curved edge beams frame into the diaphragm at a splice location and are supported on an abutment wall at the pier. This configuration of straight precast girders with curved edge beams is typically achieved with cast-in-place box girders. Trapezoidal girders were added to the WSDOT standards in 2004. Aspire_sum08.indb 46 6/24/08 1:48:42 PM