Sunday, December 02, 2001
Bridges get a space-age fix
UK engineer tests technology
By Roger Alford
The Associated Press
GRAYSON, Ky. The very notion of wrapping old bridges in polyester-thin fabric to make them stronger may sound absurd, but a University of Kentucky researcher isn't laughing.
Civil engineering professor Issam Harik said a super-strong carbon fiber material may be the key to giving new life to the nation's aging bridges, of which about 30 percent are considered substandard by the Federal Highway Administration.
Crews gathered in eastern Kentucky recently to prove Mr. Harik's case. They glued thin sheets of the fiber to the girders of a 200-foot span across the Little Sandy River.
Now, Mr. Harik said, the bridge is stronger than when it was first built.
The material, first used to strengthen the hulls of airplanes, has been available for a decade. However, state regulatory agencies have been slow to establish guidelines and bid specifications for engineers and contractors to follow when using the material on public construction, said Ali Ganjehlou, president of Advanced Building Materials Corp. in New York, which markets the material.
That's beginning to change as civil engineers such as Mr. Harik experiment with carbon fiber, which sells for $7 to $14 a square foot.
In Georgia, officials are considering draft guidelines written by Georgia Tech professor Abdul-Hamid Zureick, who has been researching the material for bridge repairs.
It's a promising technology, Mr. Zureick said. There are still some questions about the long-term performance.
A bridge over Interstate 20 in suburban Atlanta, treated with the material three years ago, still is standing strong.
Glenn Givan, chief bridge engineer for Kentucky, said the Grayson span was the first here to receive the treatment. The cost of repairing it was less than $100,000, Mr. Harik said. To replace the bridge would have cost $300,000 to $400,000.
The cost is not only the bridge replacement. ... In order to replace that bridge, the road would have to be closed. With this repair, we did not stop any traffic.
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