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Bridge Maintenance Laboratory Testing Saves Maintenance

With laboratory testing completed on a new bridge brace connector, Auburn engineers will recommend a change to Alabama's interstate highway bridge maintenance program that could save thousands of dollars. "Really, what we have been developing is a new maintenance strategy," says Mike Stallings of the civil engineering faculty. Stallings and colleague Tommy Cousins have been working with the state Department of Transportation on the project since 1993 gathering data to solve a nationwide problem of fatigue cracking in the steel connectors of diaphragm bracing.
Diaphragms, which are cross braces between the main girders, are used to minimize the normal vertical flexing of the bridges under traffic. It is a standard bridge construction technique, said Stallings. "Based on our results, only about 50 percent of the existing diaphragms must remain in place," he said. "We're recommending that as normal repairs are made, unnecessary diaphragms be removed and as connectors are replaced, the new design be used. What we've done is changed the geometry of the connection to make it more flexible."
Under extensive stress tests, it has shown to be longer lasting and more flexible than existing connectors, Stallings said.
Although the condition poses no safety hazard as long as maintenance is performed, repairs are continuous and costly. "As repairs are needed, use of the new, longer lasting connection in the diaphragms that remain could reduce maintenance costs by as much as half," Stallings said.

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