WASHINGTON — The U.S. military should share with civilian architects the lessons it has learned about protecting sensitive government buildings from terrorist attacks, including ways of strengthening a structure's lower floors to make it bomb-resistant, a new government report says.
Military structural engineers have studied bomb blasts' effects on buildings since the height of the Cold War, but the 111-page report released this month by the National Academy of Sciences said engineers haven't disseminated their findings publicly because much of the work is classified and because the public usually is not concerned about terrorism.
Building design and materials are key in determining how many people are killed or injured in a terrorist blast, the report noted.
The Oklahoma City federal building that was bombed in April was designed with minimal attention to terrorist concerns, with outer concrete columns holding up its nine concrete slab floors.
The car bomb left outside caused the collapse of the building's entire northern half, killing 168 people.
Damage in the February, 1993, car bomb attack on New York's World Trade Center was mostly restricted to the garage, in part because the building's heavy structural steel shell was designed to withstand 160-mile-an-hour winds and the impact of a fully fueled airliner.
Most of the 1,000 or so injuries in that blast occurred when smoke was drawn upward into the structure's ventilation system, and occupants stumbled down darkened stairways.
Civilian building designers should learn from engineers who design U.S. nuclear and military facilities about protecting elevator banks and ventilation, communications and fire-suppression systems, the academy report said.
Designing commercial structures to withstand a terrorist attack would add about 5% to the cost of buildings, the report said--enough, perhaps, to discourage civilian building owners and engineers.
Moreover, many architects fear security considerations will make their creations resemble bunkers, the report's authors said.
"The question is, is the public going to require blast-resistant buildings?" Richard Little, who directed the study for the academy, said.
"The technologies are within the capabilities of the design professions. . . . There was a lack of an identified terrorist threat in this country until the World Trade Center and Oklahoma City. So it's unknown whether there's a public demand" for such investment.
Strengthening the lower floors of large buildings also would improve their chances of survival in natural disasters such as earthquakes and hurricanes, the report said.