To test a new earthquake reinforcement system, the entire length of this concrete column is being wrapped in composite fiberglass jackets, called Snap Tite. The column will later undergo a simulated high-magnitude quake. At the test site, located in Kaprielian Hall, are, from left, construction worker Ray Slining, USC structural engineer Yan Xiao, contractor C.C. Myers, construction worker Michael Neuendorff and USC civil engineering chair Geoffrey Martin.

Photo by Irene Fertik

Inventor Norman C. Fawley has devised a new method (which he's dubbed "Snap Tite") to increase the strength and flexibility of concrete columns supporting key sections of freeway.

"We believe that it is a promising technology," said structural engineering professor Yan Xiao, who will conduct a crucial large-scale test of the new system this month, using the massive equipment in USC's Brandow & Johnston Structural Components Laboratory.

USC is carrying out the tests under a contract with Myers, who hopes to use the new technique to retrofit the more than 26,000 bridge supports that Caltrans has identified as candidates for reinforcement.

Fawley, who is president of the Long Beach-based NCF Industries, holds a total of 24 patents. His new system uses prefabricated composite fiberglass jackets that fit snugly around the columns.

Three or four layers of the jackets bonded with a high-strength urethane adhesive to the exterior of the column, Fawley believes, can strengthen concrete bridge supports as effectively as the method currently accepted by Caltrans - in which a layer of steel is fitted to the column - at a fraction of the cost.

Xiao, who previously worked in San Diego developing the steel jacket system, says the theory is the same for both the steel and the fiberglass systems.

During earthquakes, he explained, shaking forces cause concrete to crack and expand. Steel rings inside the columns resist these forces - but the rings failed during the Northridge quake under the Santa Monica Freeway and elsewhere.

"If you can prevent the concrete in the column from expanding by confining it in an external jacket," Xiao said, "you improve the performance. We demonstrated this in San Diego with steel. However, with steel, each layer has to be fitted and welded individually. Steel is heavy and difficult to work with."

Retrofitting a single column with a 3/16-inch-thick jacket of steel costs between $12,000 and $15,000 and takes several workers days to install. In contrast, the Snap Tite composite shells are light enough to be carried by one worker, and two workers can complete installation on a concrete column in a matter of hours. Results of preliminary tests indicate that Snap Tite can improve earthquake capability as much as steel does - by a factor of nearly three.

Caltrans' approval of Fawley's system for use on freeways depends on credible, large-scale testing. USC's participation in these tests grew out of a luncheon held last May that included Myers; Jerry Baxter, then-chief engineer at Caltrans; School of Engineering dean Leonard M. Silverman and Geoffrey Martin, chair of the Department of Civil Engineering.

Myers described Fawley's new system during the meal, and expressed frustration that he had no way of evaluating it. After negotiations, the USC engineers agreed to take on the job.

Preliminary USC testing on small, six-inch-diameter concrete cylinders indicated that the process in fact has promise.

The data convinced Myers to license Fawley's technology and invest in fabrication machinery to produce it.

Myers now hopes that USC's testing expertise will help move Snap Tite technology into the field quickly.

"When I first approached Caltrans," he said, "they said it might take two years to get tests done approving this. Now we think that USC's involvement will help put us a year ahead. We're looking to have this process tested and written up by April."

Martin emphasized that the speed of testing would in no way compromise its reliability. "The system is going to be evaluated thoroughly and objectively, using the best currently accepted methods, with a complete technical review by Caltrans. However, we do intend to do it with dispatch."

In the basement of Kaprielian Hall, workers from the Myers firm have erected four two-foot-diameter concrete columns to simulate those used to elevate freeways. The columns will be reinforced with the Snap Tite system and then undergo testing.

The most important tests will simulate the stresses that would be produced by a powerful earthquake. Assuming the system performs as expected, Martin said, the next step will likely be a trial application to one of the bridges Caltrans has scheduled for retrofitting.

Martin said additional testing and analyses are now being designed to support what could become very wide use of the process - not only in California, but around the nation and the world.

In addition to its strengthening effect, the composite jacket seals out environmental agents - such as salt water - that accelerate decay and aging of steel-reinforced concrete structures.

"If this technology in fact tests out," said Martin, "it could be very widely useful. We think it is in everyone's interest to evaluate it thoroughly but to do so quickly; so we are making this a priority."