Title: UHPC Alternative for the West Wilson Bridge

Author(s): David Gee

Publication: Web Session

Volume: ws_S22_DavidGee.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 3/28/2022

Abstract:
The West Wilson Bridge over the Turkey Creek in Walton County, Florida has a total length of 96-feet and total width of 26 ft-8 in. It has a skew angle of 30 degrees. Tight vertical clearance had limited the structural depth of the superstructure to 17-inches. Accordingly, the designer had opted for a cast-in-place flat slab, continuous for three equal spans, 32-feet each. The Structures Design Office of FDOT collaborated with e. Construct to develop a second superstructure alternative, designed with precast concrete UHPC products. The alternative will be presented to bidders without any bias or subsidy. Thus, this is believed to be the first bridge in the US to be made with UHPC in competition with one of the lesser expensive conventional concrete systems, the cast-in-place flat slab system, which had been modified in this case to use GFRP reinforcing due to the extremely aggressive environment. Several options were initially studied. A single span system was found unfeasible. A two-span system was not permitted by FDOT to avoid a pile foundation in the center of the channel. It would have resulted in a span/depth ratio of about 65. A three- span system with the center span increased from 32 to 44 feet was selected as a project enhancement. Then segmentation methods were studied. After consultation with local precasters, it was decided to frame the superstructure with six box slabs, each with a total width of 4 ft-2 in. and a total depth of 1 ft -5in. A nominal four-inch UHPC grouted space is provided between slabs. It was further decided to create a unique design by allowing all three spans of each box slab to be cast as one 96 ft long piece, thus reducing the number of pieces to only 6 and eliminating all pier joints. The 32-44-32 ft. span configuration also improved structural efficiency and achieving the vertical curve profile. This presentation focuses on design approach. It will cover how camber was controlled to allow for a 5-inch rise of the bridge.