Precast Solutions - September/October 2008 - (Page 13) strands prevents the development and propagation of longitudinal cracks as a result of limiting differential deflection and rotation between adjacent box beams due to eccentric service loads. Similar post-tensioning arrangements were also tested and proven in the field during the Bridge Street Bridge project. under service conditions. In June 2007, six traditional epoxy-coated steel strands were removed from the cable stays without changing the bridge’s structural integrity and replaced with CFCC strands. A newly patented cradle system had been installed in the new bridge to provide longterm durability and ease of cable maintenance. With the CFRP strand at Penobscot Narrows Bridge and Observatory Harsh winter conditions and corrosion in the Waldo Hancock Bridge in Maine led to the premature deterioration of the 75-year-old steel suspension structure. Concerned Maine Department of Transportation (Maine DOT) officials implemented a fasttrack bridge replacement project. While developing the bridge design, the project team realized this was an opportunity to demonstrate the reliability of using posttensioned carbon fiber strands. So carbon fiber composite cable (CFCC) strands in three stays of a new 2,120-foot-long (695-meter) replacement bridge to assess CFCC construction deployment and performance cradle design, cable stay strands serve as tensile elements that are individually threaded continuously from an anchorage at the bridge deck through a free length of high-density polyethylene sheath, through the cradle in the pylon and back through another sheath and anchorage at the bridge deck on the opposite side of the pylon. This allowed easy replacement of the steel strands with CFCC strands for the demonstration project. A nested layering of protection for the strand includes: epoxy coating on the strands; dry air environment within the annular space surrounding each strand; and HDPE sheathing that works with the cradle system to create a closed environment. Monitors record BOOTH 1049 THE PRECAST SHOW SEPTEMBER/OCTOBER 2008 | PRECAST SOLUTIONS 13 http://www.grifcote.com http://www.grifcote.com
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