THE PRACTICE AND POPULARITY OF checking load capacity of repairs on structures may be turned on its head if a test method recently brought over from Europe finds widespread acceptance in the U.S. Rather than spending days using traditional tools such as large water-filled bladders or educated guesses, testers use off-the-shelf electronics and hydraulic equipment to apply and measure loads in hours.

"The system consists of hydraulically powered load applicators, instrumentation to measure deflections and strains, and computer-based data acquisition electronics," says Antonio Nanni, a civil engineering professor at the University of Missouri-Rolla. Rather than wondering about the overall structure, "it tests just what [the repair] is doing,'' he says.

Observers say Europe is ahead of the U.S. because government-based engineering boards there have required independent testing for years to verify structural performance. "It's embedded in the culture,'' says Nanni. The popular U.S. methodology for designing structural repairs includes a visual inspection, a paper or computer-based analytic approach and concrete core sampling in advance. But there is no follow-up, says Nanni. "You make a recommendation, but there's no verification,'' he notes.

Existing tests, say experts, can be somewhat risky. "With a water bladder, you can overload pretty quickly,'' says Jay Thomas, a vice president with concrete-repair contractor Structural Preservation Systems Inc., Baltimore. He says some buildings require shoring before testing. "This approach is slightly different,'' adds Nanni. "You apply a few hundred pounds or several thousand kips with the same system.'' SPS uses the approach on carbon-fiber upgrade projects, the first time nearly six months ago on an Atlanta parking garage upgrade. "Setup, test and breakdown took about five hours,'' says Thomas. Using traditional methods, "it would have taken days.''

SPS is now starting work on a $4.3-million structural upgrade to an Oklahoma City convention center. It entails applying 200,000-sq-ft of carbon-fiber sheet to concrete beams and joists. Thomas says the ability to test this way was critical to getting the work. Nanni, a project consultant, plans to present the data early next year in the hopes of ultimately changing industry load-testing practices and standards. "I don't expect resistance because engineers want in situ testing,'' he says. "They see the need for it.''