ASPIRE Summer 08 - Aspire - The Concrete Bridge Magazine

STATEConcrete Bridges inWashingtonStateby Jugesh Kapur and DeWayne Wilson, Washington State Department of TransportationThe Selah Creek Fred G. Redmond Bridges on I-82 near Yakima opened in 1971.Concrete is the material of choice forthe majority of bridges in the State ofWashington. Approximately 2600 out of 3000bridges maintained by the Washington StateDepartment of Transportation (WSDOT) have amain span type that consists of concrete. The oldestof these bridges dates back to the early 1900s.The first known use of a precast, prestressedconcrete girder bridge in Washington was in 1954for a bridge over the Klickitat River on State Route142. The center span of this three-span bridge is90 ft and consists of four precast segments about22 ft in length that were supported on falseworkin place and then post-tensioned together. Thecontractor chose to install the girder in units,based on the lifting capacity of his crane.Technology and equipment have advanced sincethen to allow current bridges with spliced girdersto have lengths in excess of 200 ft.There are two major statewide transportationimprovement programs underway. The first,known as the “Nickel” funding package, began in2003 with a total budget of $3.9 billion to addressprimarily congestion and safety on 158 projects.The second, known as the “TransportationPartnership Account” began in 2005 with a totalbudget of $7.1 billion to address preservation andmobility on 274 projects. Concrete bridges willplay a big part in these new programs.Selah Creek ArchesThe twin Selah Creek Fred G. RedmondBridges on I-82 provide a connection south fromEllensburg to Yakima. They were the largest archspan bridges in the United States at 549.5 ft whenthey opened to traffic in 1971. The top of the archspan is 325 ft above the canyon and requiredfalsework to be built from the valley below. Thesuperstructure on each bridge consists of 17 spansof prestressed concrete girders that are 78.5 ftlong. These two bridges are examples of the useof concrete for nearly 780 interstate bridges builtbetween 1955 and 1975 that are now 30 to over50 years old.South 317th St HOV AccessIn 2006, a bridge was opened over I-5 nearFederal Way to provide direct access for busesand high occupancy vehicles from I-5. Bridgeengineers decided to use precast, prestressedconcrete trapezoidal tub girders 5 ft wideand 6 ft deep that were spliced together withpost-tensioning. The bridge span is curved atthe intersection with the access ramps toaccommodate turning buses. The structure is 128ft long with four spliced precast, trapezoidal tubgirders, each consisting of 35-ft- and 88-ft-longsegments. The segments were temporarilysupported on falsework and then post-tensionedtogether. The bridge has 50-ft radius curvesconnecting to the ramp side. Curved edge beamsframe into the diaphragm at a splice locationand are supported on an abutment wall at thepier. This configuration of straight precast girderswith curved edge beams is typically achieved withcast-in-place box girders. Trapezoidal girderswere added to the WSDOT standards in 2004.Precast trapezoidal tub girder.46 | ASPIRE, Summer 2008