28 April 2008 21:18 [Source: ICIS news]
Louis Luedtke, president of the National Composite Center (NCC) at
A private company spun off from the centre has just completed installation of a fibre reinforced polymer (FRP) composite bridge in Anderson Township, Ohio, one of more than a dozen such structures put in place in Ohio by the centre since initial work was begun in 1999, Luedtke said.
The latest bridge, built and installed by Composite Advantage Co., is located about 10 miles southeast of
Polymer bridge spans are manufactured in sections and assembled on site and typically are composed of either vinyl ester or polyester plastic, reinforced with glass fibres around urethane or polystyrene foam support structures, according to Luedtke.
Including decks and support structure, a composite bridge will weigh about 1 tonne per linear foot of span, although that weight ratio could vary considerably depending on design and specific composition, he said.
Even at 1 tonne per span-foot, a composite bridge is only 20% the weight of traditional construction using steel and reinforced concrete, according to the centre.
Luedtke said polymer bridge spans are greatly superior to conventional steel and concrete structures in resisting corrosion by maintenance chemicals, such as winter road salt, and fracturing from seasonal temperature shifts.
Although a polymer bridge costs about 25-30% more than a similar span built from traditional materials, it has a life-expectancy of 100 years compared with 50-60 years for steel and concrete, Luedtke said. A composite structure can bridge any span with integrity equal to or greater than steel and concrete, he noted.
Luedtke also noted that many of the bridges that now operate under load restrictions - meaning heavier vehicles such as commercial trucks are barred from using them - could be returned to full service if concrete bridge decks were replaced with composite decks that would considerably reduce load pressure on underlying structures.
Earlier this year a two-year federal infrastructure study recommended that federal and state governments should spend more than $11,000bn (€7,000bn) to repair and improve the nation’s infrastructure.
That study came in the wake of a major highway bridge collapse in August 2007 at
Luedtke said that in addition to the higher cost of composite bridges - which can be overcome as production increases - a major obstacle is resistance among local government authorities.
“County engineers often are elected officials with limited budgets, so they will put in a lower-cost conventional bridge that will get them through their 20-year tenure in office rather than a costlier composite structure that will last a century,” Luedtke said.
($1 = €.64)
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