THE CONCRETE BRIDGE MAGAZINE

WINTER 2015

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/439391

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CREATIVE CONCRETE CONSTRUCTION Porter Creek Bridge by Farshad Mazloom, Kie-Con Porter Creek Bridge was advertised for public bid based on a single-span, cast-in-place concrete box-girder bridge in December of 2012. Contract was awarded in early 2013 with a tight contract schedule, not considering the anticipated heavy rain during the winter season. The bridge was opened to traffic in 2014. The new bridge was designed to replace a five-span concrete bridge built in 1935. The precaster proposed using seven, 78-in.-deep by 160-ft-long wide flange girders. These girders are, to date, the longest non-spliced precast concrete girders in California. The precast concrete girder solution eliminated the need for any falsework in the creek, which is an environmentally sensitive habitat. This solution allowed the bridge work to continue during the annual environmental-hold period, which starts on October 15 of every year. A major key to the success of the project was how quickly the calculated decision was made by the general contractor, owner, and engineer to approve the value-engineering proposal for the bridge. Design During the value-engineering design phase, it was discovered that the girders had to travel under an existing historical monument just 1 mile west of the bridge, this tight headroom was the major factor in determining maximum height of the girders. Once the girder height was determined, it was just a matter of simple calculations to design the quantity of girders needed for the bridge.

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