FALL 2017

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

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Page 39 of 63

CONCRETE BRIDGE TECHNOLOGY Precast Concrete Innovations for a Cast-in-Place Cable-Stayed Bridge by Craig Finley, Finley Engineering Group Inc. Ohio's Ironton-Russ ell Bridge replacement, renamed the Oakley C. Collins Memorial Bridge, opened to traffic in November 2016. As with many complex projects, the road leading to the bridge follows a much straighter path than the one blazed by the construction team to create this stunning cable-stayed bridge crossing the Ohio River. Starting with pre-bid engineering, the construction team worked together to identify the most challenging, timeconsuming, and risky aspects of the project. Developing solutions to these issues led to a change in the construction scheme that required casting the back spans on falsework to eliminate the use of two form travelers. The modifications allowed the main span to be cast-inplace using a segmental, unidirectional cantilever method. To accomplish this, several innovative precast concrete solutions were developed to realize the new construction sequence. This included incorporating the contractor's strengths, equipment, and technology with the pioneering application of traditional precast concrete, as well as customdesigned adaptations to conventional construction means and methods. Precast Concrete Innovations This project benefited from the strengths of precasting by incorporating the following details at key areas to enhance the constructability of a traditional castin- place cable-stayed bridge design: - precast concrete transverse beams - precast concrete cable stay anchorage blocks - precast concrete footing coffercell forms Precast Concrete Transverse Beams Revising the construction sequence to cast the back span on falsework had huge advantages to the project schedule and construction access. It allowed the back-span superstructure to be cast well in advance of the unidirectional cantilever construction for the main span. A large side benefit was creating access to the pylon from the deck level to simplify construction of the pylons early in the schedule. The use of precast concrete transverse beams provided the same benefits realized on routine bridge construction for the casting of the backspan superstructure deck. In addition, by providing a clear span between edge girders, a greatly simplified falsework system could be used that only required support at the edge girders. Constructing the back spans on falsework simplified construct ion, reduced construction time, increased project safety, and reduced the amount and size of the equipment required for the pylon and main span construction on the (cont. next page)

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