Across the nation
Diesel suspected in 7 WTC collapse
By James Glanz
New York Times News Service
Published November 29, 2001
NEW YORK --
Almost lost in the chaos of the collapse of the World Trade Center's twin towers is a mystery that under normal circumstances would probably have captured the attention of the world: the collapse of a nearby 47-story building, seven hours after flaming debris from the towers rained down on it, igniting what became an out-of-control fire.
The 2 million-square-foot building, 7 World Trade Center, had suffered mightily from the fire, and had been wounded by beams falling off the towers. But experts said no building like it, a modern, steel-reinforced high-rise, had ever collapsed because of an uncontrolled fire. They have been trying to figure out exactly what occurred, and whether they should be worried about other buildings like it around the country.
Engineers and other experts have begun considering whether a type of fuel stored inside the building created intensely hot fires like those in the towers: diesel fuel intended to run electricity generators in a power failure.
One tank holding 6,000 gallons of fuel was in the building to provide power to the mayor's emergency command bunker on the 23rd floor. Another set of four tanks holding as much as 36,000 gallons was just below ground on the building's southwest side, for generators that served some of the other tenants.
"Even though Building 7 didn't get much attention in the media immediately, within the structural engineering community, it's considered to be much more important to understand," said William F. Baker, a partner in charge of structural engineering at the architectural firm Skidmore, Owings & Merrill.
Across the country, diesel-powered generators are used in buildings like hospitals and trading houses, where avoiding power outages is crucial. Partly for that reason, a definitive understanding of what happened in 7 World Trade Center is vital to investigators, said Jonathan Barnett, a professor of fire protection engineering at the Worcester Polytechnic Institute.
Most of the three other buildings in the complex, 4, 5 and 6 World Trade, remained standing despite suffering damage of all kinds, including fire. Still, experts concede, in a hellish day, 7 World Trade might have sustained structural injuries never envisioned in fire codes.
As the twin towers collapsed, large pieces of them smashed parts of 7 World Trade and set whole clusters of floors ablaze.
Within the building, the diesel tanks were surrounded by fireproofed enclosures. But "if the enclosures were damaged, then yes, this would be enough fuel to explain why the building collapsed," Barnett said.
Barnett and Baker are part of an assessment team organized by the American Society of Civil Engineers and the Federal Emergency Management Agency to examine the performance of several buildings during the attacks.
Copyright © 2002, Chicago Tribune