North America's first steel-arch and stress-ribbon bridge now adorns the city of Fort Worth, Texas, serving as a connection from the city's central business area with the arts district and its largest and oldest park.
The $2.5-million Phyllis J. Tilley Memorial Pedestrian Bridge stretches out 366 ft and is 12 ft, 9 in., wide. Several criteria on the part of the owner made the steel-arch, stretch-ribbon combo an ideal solution for the bridge. Stakeholders wanted an aesthetic structure, but the location is an urban area sensitive to increased flooding, so the bridge had to withstand being topped by more than 12 ft of floodwaters.
Comprising a post-tensioned steel stress ribbon and carrying prefabricated concrete deck panels, the bridge rests on the rounded apex of the arch over the river. Construction required Rebcon Inc. to install two ribbons of steel, each 330 ft long, 20 in. wide and 1¾ in. thick, then tensioning each ribbon with more than 390,000 lb of force. Temporary supports on the steel arch during welding enabled the team to complete work without having to be physically in the river.
The ribbon and arch work in concert to create an efficient structure, with the tension in the stress ribbon balanced against the opposing thrust loading from the steel arch.
Owner: City of Fort Worth
Architect: Freese and Nichols Inc.
General Contractor: Rebcon Inc., Dallas