Ultra-High Performance Concrete Waffle Slab Bridge Deck for Wapello County, Iowa
This article reports on two bridge projects in the state of Iowa that have been completed using ultra-high performance concrete (UHPC). The first was the Mars Hill Bridge, a single-span, 110-ft (33.5-m) long, prestressed I-girder bridge, in Wapello County, Iowa. The three girders of the cross-section were cast with UHPC. The second bridge was the Jakway Park Bridge, a three-span 110-ft (33.5-m) long bridge, in Buchanan County, Iowa. The center 50-ft (15.2-m) long span was constructed with UHPC using the pi-girder cross section developed by the FHWA and the Massachusetts Institute of Technology. Prior to constructing the Wapello County bridge with precast waffle slab deck panels made with ultra-high performance concrete, two test panels were manufactured and subjected to static and fatigue load testing. The authors describe the design and testing of these panels, finding that no fatigue damage was noted after 1 million cycles of loading applied to the laboratory specimen (to represent wheel loads). The authors also briefly report on progress in the bridge construction (which was delayed by flooding in Iowa in 2010). Readers wishing to obtain more information about the Iowa project and UHPC are referred to www.fhwa.dot.gov/hfl/partnerships/coreslab/phase1/app_index.cfm.