Anderson, a professor of civil engineering at USC. The steel is protected to certain temperatures and for certain periods of time, but “an explosion of this magnitude would have exceeded all those limits,” said James C. “What basically happens is that one floor falls on top of the floor below it, and with one floor falling on top of another there’s no way to stop it.” “The technical term is progressive collapse-the slang term is pancaking,” said Ron Klemencic, president of Skilling Ward Magnusson Barkshire, the Seattle firm that engineered the World Trade Center. The weight of the floors above then causes them to crash.
Terrorism experts were calling the attack “low-tech and high-concept.”Įven though structural steel used in buildings is coated with a fireproof material, extreme amounts of heat cause the steel to soften and lose its strength. “The plane was really a highly explosive bomb,” he said. “It was very well thought out,” said Hank Koffman, who directs the construction engineering department at USC. One thing led to another, and it just kept snowballing.” Some fuel probably got into the elevators and spread the fire. “The fuel went through a couple of floors, loaded them with fuel, and the impact opened a corridor to the outside for air. “The plane probably made its way halfway to the core of the structure,” Gustafson said. Because the planes were scheduled for transcontinental flights, they would have been fully loaded with fuel. A Boeing 757 has an 11,000-gallon fuel capacity. of Blue Springs, Mo., one of the world’s leading demolition experts.Ī Boeing 767 has a fuel capacity of 20,000 gallons. Instead, the impact of the planes themselves, and the tremendous heat generated by tons of burning jet fuel-upward of 1,000 degrees Fahrenheit-would suffice to destroy the buildings, said Scott Gustafson, owner of Demtech Inc.
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