Shared Data on Bomb-Proofing Buildings Proposed

A federal agency proposed Tuesday that military research on making large structures resistant to bombs be made available to the owners of skyscrapers and other commercial buildings.

The Defense Department has been conducting research for years on how to make embassies and other federal buildings bombproof. The research began after a bomb destroyed the Khobar Towers military barracks in Dhahran, Saudi Arabia, in 1996, killing 19 U.S. soldiers.

Now, two months after terrorists leveled the twin towers of New York’s World Trade Center, the National Research Council wants the results of the military research released to the public so existing office buildings and skyscrapers can be hardened and new buildings made more resistant to bomb blasts.

The council, an arm of the National Academy of Sciences, issued a report Tuesday that called on the Defense Threat Reduction Agency to make its research results available in a form that is understandable to civil engineers and construction officials.

“One should not have to be an explosives expert to understand this material,” said Mete A. Sozen, a Purdue University engineer who heads the National Research Council committee that prepared the report.

The council hopes that more readily available information will speed changes in building standards, saving lives and reducing injuries.

Doug Sunshine, blast mitigation program manager for the Defense Threat Reduction Agency, said the agency wants to make its findings known to American engineers but not to terrorists. Most researchers, he said, agree that design procedures and guidelines should be readily available while information on the design or vulnerability of specific buildings should be guarded.

“You never reveal the threat you design a building to,” Sunshine said. As long as a terrorist doesn’t know the strength of a building, “he doesn’t know how big a bomb to bring.”

Although there may never be an “Idiot’s Guide” to bomb-proofing a building, “there’s a desire to get information out so people can understand it,” Sunshine said.

The blast mitigation program is releasing some information through journal articles, and Sunshine said blast-resistant structures are being built.

Many engineers credit recent renovations at the Pentagon for limiting casualties during September’s terrorist attack. Sunshine said structural improvements helped reinforce the building and that blast-resistant windows may have reduced the spread of the fireball.

Sunshine cautioned that no known technique would have prevented the catastrophic collapse of the twin towers.

However, he said, the federal building in Oklahoma City could have been better protected against the 1995 bomb that left 168 dead. That building suffered a progressive collapse--as one part fell, it dragged other parts with it. About 87% of the occupants of the parts of the building that collapsed were killed; only 5% died elsewhere.

Sunshine said carbon fiber wraps on the building’s concrete columns might have allowed the columns to bend without breaking.

The cost of blast-proofing buildings ranges wildly, depending on the level of protection desired.

Purdue’s Sozen estimates that the most basic level of protection for a new building--blast-resistant windows--adds about 2% to the total cost. To retrofit an existing building could cost more than 15% of the value of the building, he said.

“I started my work on this committee saying we have to be careful not to interfere” with commerce, Sozen said. “Now I’m of the opinion . . . that it is essential to make changes . . . to protect people.”

Although the military has established minimum construction standards for “force protection,” Sunshine said, commercial building owners or managers are balancing cost against risk to establish an appropriate level of protection.

After Sept. 11, tenants of skyscrapers could be expected to be more security conscious than those of small office buildings in small towns. But a spokesman for Chicago’s Sears Tower said only one tenant was leaving because of security concerns.

In Los Angeles, a number of firms are assessing their real estate, said Geoffrey M. Ely, president of the Building Owners and Managers of Greater Los Angeles.

Ely pointed out that one of the World Trade Center towers survived “a very powerful bomb” detonated in the garage in 1993. He warned against basing building standards on any “isolated study” when a range of possible security measures could be as effective, he said.

In California, high-rise office tenants can take some comfort in knowing that construction standards to protect buildings against earthquakes also provide some protection against bombs. The only exception, Sozen said, is that more mass is good when protecting against bombs but not so good against earthquakes.

The National Research Council report even suggests emulating the earthquake engineering community in disseminating technical information.