THE CONCRETE BRIDGE MAGAZINE

FALL 2016

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.

Issue link: http://www.aspiremagazinebyengineers.com/i/740919

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PROJECT Precast Concrete Segmental Substructures by Brenda Nichols, Cianbro Corp. Bridges utilizing precast concrete segmental substructures have been built in the United States since the 1970s, but they are not nearly as common as bridges with segmental superstructures. This article describes the use of precast concrete segmental columns, explores their benefits, and establishes reasons why a contractor in particular might choose this construction method. What Are Precast Concrete Segmental Substructures? Examples of precast concrete segmental substructures can include footings and pier caps, but this article will focus on the classic segmental model of precast concrete column units that are stacked on top of each other and then made continuous with vertical post-tensioning. The column segments can be simple rectangular shapes, such as those used on the Chesapeake & Delaware Canal Bridge, the South Norfolk Jordan Bridge, and the O’Callaghan-Tillman Memorial Bridge. Alternatively, the segments can consist of a more-complex shape, chosen for aesthetic or other projectspecific reasons. Some examples of these types of column segments can be seen in the Sunshine Skyway Bridge and the Linn Cove Viaduct. In general, the shape of the column segments is a balance among the structural requirements of the design, the aesthetic goals of the owner, and the weight limits of the contractor’s transportation and erection equipment. Benefits The benefits of using a precast concrete substructure are similar to the benefits achieved from using a precast concrete superstructure. Speed of erection of precast versus cast-in-place

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