Test Failure Won’t Interrupt Quake Retrofitting

Despite the testing failure of quake repair methods for steel-frame buildings, Los Angeles officials said they will continue with the same retrofitting program while researchers conduct further tests throughout the summer.

Preliminary testing at the University of Texas at Austin found that the repair methods recommended by the Los Angeles Department of Building and Safety failed when subjected to a simulated earthquake of 7.0 magnitude.

Researchers and city officials stressed Monday that additional tests were needed to determine what other repair methods would prevent the widespread cracking of streel-frame commercial buildings like that resulting from the Northridge quake.

“We’ve identified the virus, and now we need to find a vaccine,” said Geerhard Haaijer, vice president of the American Institute of Steel Construction in Chicago.

The results of the preliminary tests caused researchers to suspend five remaining simulations and bring their results to Los Angeles, where they met with city officials at a steel industry symposium near Los Angeles International Airport.

But after the meeting, city officials said they would not immediately abandon the methods that have been recommended for both new construction and the repair of quake-damaged steel-frame buildings.

“It is still too early to tell on this,” said Richard Holguin, assistant chief of the city’s building bureau. “There are still lots of tests to be run.”

If the tests are accurate, Holguin said, the “repairs that are being recommended do not appear to provide a permanent correction.”

Geoff Ely, executive director of the Building Owners and Managers Assn., representing about 1,500 members throughout Los Angeles County, called a Times report Monday of the tests “disturbing.” But Ely said he cannot gauge the impact to building owners until more information about the tests is released.

Additional information on the tests is expected to be released today during a symposium of the American Institute of Steel Construction at the Airport Marriott Hotel. Among the speakers will be University of Texas professor Michael Engelhardt, who told The Times last weekend that the tests showed that the current retrofitting methods do not work. “Even with the improvements, there were cracks early on in the tests,” he said.

Steel-frame office buildings, designed to bend with the forces of an earthquake, were considered among the safest in riding out a temblor. But after the Northridge quake, building experts were shocked to find cracking on welded connections of beams and columns of at least 90 buildings, mostly in the San Fernando Valley and on the Westside.

Results of the Texas study--the main effort to find a solution to the problem--disturb experts because the welding methods and design changes tested are currently being used to make repairs to quake-damaged high-rises and in new construction.

The Los Angeles City Council voted in May to draft an ordinance that would require the owners of steel-frame buildings to inspect the buildings for damage within three months of notification by the city. Repairs, using the methods questioned by the Texas tests, would have to be completed within one year after they are recommended by inspectors, under the proposed ordinance.

Wilfred Iwan, chairman of the California Seismic Safety Commission, said he had not received any information on the Texas tests and is eager to have more information so the commission can complete a set of changes to the state’s building codes requested by Gov. Pete Wilson after the Jan. 17 quake.

“I think it’s important for that report to get out,” he said.

When Iwan read The Times’ report on the tests Monday, he said many questions came to his mind about how the tests were conducted and what recommendations will be made as a result.

“Clearly there is a potential for a huge problem,” he said. “What it may be saying is you have to be careful of quick solutions.”

The Texas test used life-sized columns and horizontal beams that were welded together in California and shipped to the University of Texas, where a hydraulic arm was used to shake the beam, simulating a quake.

After the steel frames were strengthened with plates and welds, some connections nonetheless broke when the beams were shaken up and down just once.

The city’s repair recommendations to the owners of steel-frame buildings were based on engineering simulations conducted before the temblor. These showed that joints reinforced in certain ways, usually with steel plates, performed better than those built to the current code.

City officials said owners of about 30 steel-frame buildings have taken out permits to make repairs, and about half of the repairs have been completed.

Ely, of the building owners group, could not say how many steel-frame buildings have begun to receive the repair work recommended by the city.