MODEL COULD CUT QUAKE-SAFETY COSTS : TECHNIQUE TARGETS LIMITED INSPECTION POINTS FOR FINDING DAMAGE.

Byline: David Bloom Daily News Staff Writer

Building owners have spent hundreds of thousands of dollars searching their high-rises for damaged welds since the Northridge Earthquake, but the costs could come down if an experiment with the Van Nuys Municipal Courthouse works.

And they have no choice. A city ordinance passed last year requires them to pull off the ``skin'' of their buildings to check for structure-weakening cracks that resulted from the Jan. 17, 1994, temblor.

But now Santa Monica engineer Garry Hart says he may have found the solution in a computer model that identifies where the cracks should be. If it works, building owners need check only a few of those cracks, and can believe that their building is safe if they're OK.

``The engineering community is putting a lot of energy into this,'' said Carol Kindler, who oversees quake recovery efforts for the county Administrative Office. ``The model will look and say, `These are the connections that are most likely to be damaged.' We're going to find out if the modeling is valid.''

It might cost as much as $1 million to inspect a large high-rise the current way - by tearing into the structure to expose the steel welds, said officials with Los Angeles County and the Federal Emergency Management Agency.

FEMA, which must help pay to repair or replace about 200 government high-rises damaged in the Northridge Quake, and Los Angeles County, which owns many of those buildings, began looking for a less expensive alternative.

The county hired Hart to develop the model for $32,000 last year. On April 1, the Board of Supervisors approved a second, $107,000 phase of its contract with Hart's company to allow workers to determine how well the model works.

The key to savings is to determine if a building's welds were damaged in the quake. Fixing a damaged building is going to cost a lot no matter what, but building owners don't want to spend $1 million just to check the joints.

``These are all hidden damage and unfortunately, no one has X-ray vision to see all of it,'' said David Duffer, FEMA's infrastructure chief. ``You're talking big bucks (to do an inspection).''

At the Van Nuys courthouse, workers will actually open up about 85 connections that the model says are most likely to have quake damage. Based on how much damage they find, they might be able to avoid opening up any more of the nearly 600 connections in the building.

Of course, if the first inspections find damage, the building could require extensive and costly repairs, but the experiment would still prove a success.

That's important, officials said, because dozens of Southern California buildings are suspected of having damaged welds, raising questions about their ability to withstand a second quake.

``It's three years and three months after the fact,'' Duffer said. ``We'd like to get these buildings repaired because no one can predict when the next quake's going to occur.''

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