JEC COMPOSITES MAGAZINE - Issue #77 - December 2012 - 31

Erection of multiple HCB’s shipped on one truck

the concrete for the arches in the HCB units. By simply placing a hopper with a steel tube into the tops of the beams, it was possible to fill each beam in approximately 20 minutes. Again, the contractor was able to place all of the concrete compression reinforcement in one span within one day. Further, the reduced shipping and installation costs associated with the advanced composite structure made the solution cost-competitive with the conventional precast box-beams on a first cost basis. One of the biggest advantages of HCB is the extreme lightweight for shipping and erection. Each of the 21.3-m-long beams for the Knickerbocker Bridge weighed only 2.27 metric tons. As a result, four HCBs could be shipped on a single truck instead of one truck per beam as would have been required for precast concrete beams. Further, the beams could be erected using a small crane instead of mobilizing a 200-ton crane. This resulted in a significant cost savings. Finally, no deck forms were required. Once the beams were filled, the contractor began placing reinforcing for the deck pour. With top flange widths of 1.2 metres, the beams were placed tip to tip so that no deck forming was required. Scupper details, screed rails and reinforcing details were no different than those for a comparable precast concrete bridge. The first half of the deck was cast in October of 2010. After working through

the winter to complete the remaining piers, the contractor completed installation of the second half of the HCB superstructure in April of 2011. The bridge was officially opened to traffic on June 11, 2011. “I will definitely design with HCB again,” said Calderwood. “I think it is a wonderful product and when used in the right location, it will benefit bridge owners for a long time to come.”

Focus
The 164.6-m Knickerbocker Bridge in Boothbay, Maine, is the longest fibre-reinforced bridge ever constructed. Its lightweight hybrid-composite beams, designed by John Hillman of the HC Bridge Company and built by Harbor Technologies, are made of a corrosion-resistant fibre-reinforced polymer shell filled with reinforced concrete. The shell is one third the weight of steel and one tenth the weight of concrete, allowing for quicker construction (it takes just one backhoe to place the beams), and each beam lasts 100 years longer than ordinary concrete and steel, at a similar cost. Source: www.popsci.com

Other projects using HBC
As a result of the success of this project, four additional HCB bridges are in various stages of design and construction, including multi-span bridges and longer spans on the order of 37 metres. With economies of scale and further advances in fabrication automation, it is now possible, with the HCB, to make sustainable structures using advanced composites a mainstream component for reconstruction of the world’s deteriorating infrastructure. “What makes the Knickerbocker Bridge

unique is not only the HCB framing system, but the fact that this will be the longest composite vehicular bridge in the world, the first to be made continuous for live load, and the fact that this has been accomplished with a structure that was no more expensive than a conventional concrete box beam bridge,” said Hillman. Kim Suhr, vice president, Wyman & Simpson, also noted the long-term benefit of HCB – its anti-corrosive properties. “I am confident that this bridge will have a longer life span in this corrosive salt water environment than if it was constructed of simply steel or concrete,” he said. “We definitely will use HCB again.”

Inside struture og HCB

No77 December 2012 /

jec composites magazine 31

http://www.popsci.com

JEC COMPOSITES MAGAZINE - Issue #77 - December 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #77 - December 2012