ARE VALLEY BUILDINGS QUAKE SAFE?

Byline: David R. Baker Staff Writer

As engineers study Taiwan's quake wreckage, researchers say the construction style of many San Fernando Valley buildings is particularly safe and among the most likely to survive a similar quake.

Key factors in whether a building remains intact include the buildings' age, their construction type and the attention paid by inspectors.

``One of the problems in these other countries is that while the design may be OK, there's no checking the contractors to make sure they're using the right materials,'' said Richard Holguin, executive officer of Los Angeles' building and safety department.

All new buildings in the city must meet tough safety standards derived from years of experience with quakes, but officials said older structures were built to the less-stringent codes of their times and might not survive a magnitude-7.6 quake like the one that struck Taiwan.

``I don't know how many of these types of buildings are around, but most of us think there's a lot of them, so there could be a lot of damage,'' said John Wallace, an associate professor of civil engineering at the University of California, Los Angeles, who recently returned from quake-ravaged Turkey.

Creating a system of regular inspections for such buildings wouldn't be easy, he said. Unlike fire safety inspections which can be done quickly and simply, checking the structural integrity of a building involves studying blueprints, peering into walls and possibly taking samples of concrete.

``It can get to be an extremely expensive proposition,'' Holguin said.

The good news is that city officials said a high percent of the Los Angeles buildings are new, and the city strictly enforces construction codes designed to ensure that buildings don't collapse in a quake. Turkey, for example, has similarly tough codes that are routinely ignored.

In Los Angeles, city officials carefully monitor construction of new buildings using codes honed by experience gleaned from the city's own history of earthquakes. But unless they are targeted by a specific retrofit program or are about to be remodeled, older buildings are not routinely inspected, Holguin said.

According to engineers, some building types have, over time, proven better at weathering a quake than others.

Reinforced shear-wall construction - which involves solid, continuous walls stretching between floors of a building - often resist the shaking of an earthquake. They are also relatively easy to build well, said Thomas Heaton, professor of engineering seismology at the California Institute of Technology.

``I have a preference for shear-wall buildings, because with them the details are a little less critical,'' he said.

``It's easier to get it right.''

Houses tend to be safe, because they're light, compared to office or apartment buildings.

In general, buildings constructed after the mid-1970s usually fare better than older structures because they had to meet far tougher building standards than did older buildings.

Still, experts say it is hard to know how safe a building is without serious research.

``Unfortunately, it's very difficult to tell,'' Heaton said. ``Even trained people would have to pore through the plans of buildings. And even if they had the plans, they might not know if it was built according to plan.''

The often arcane details of building codes will take on added importance as engineers from around the world converge on Taiwan to study how buildings fared in the massive quake.