DESIGN OF BUCHANAN COUNTY, IOWA, BRIDGE, USING ULTRA-HIGH PERFORMANCE CONCRETE AND PI-GIRDER CROSS SECTION

Buchanan County, Iowa, was granted funding through the TEA-21 Innovative Bridge Construction Program (IBRC), managed by the Federal Highway Administration (FHWA), to construct a highway bridge using an optimized PI girder section with ultra high-performance concrete (UHPC). When completed, the Buchanan County project will be the first application of the PI section for a highway bridge in the United States. The girders will be pretensioned longitudinally and tied together transversely with mild reinforcing steel and steel diaphragms. The bridge will use the second generation of the Pi girder section. The Office of Bridges and Structures at the Iowa Department of Transportation and the Bridge Engineering Center at Iowa State University have completed the bridge design. The basis for the design was conventional and finite element analysis, which was validated by prior laboratory testing of the first generation Pi girder section at the FHWA’s Turner-Fairbank Highway Research Center in McLean, Virginia near Washington, DC. The paper will cover the design and analysis effort by the Iowa DOT, Office of Bridges and Structures and the Bridge Engineering Center at Iowa State University. In addition, the current status of the project will be covered.