Jim Destefano
CNN BREAKING NEWS
Amateur Video of Immediate Aftermath
Aired September 11, 2001 - 16:20 ETTHIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
AARON BROWN, CNN CORRESPONDENT: Jim Destefano is a structural engineer. He knows about big buildings and what happens in these sort of catastrophic moments, He joins us from Deerfield, Connecticut on the phone.
Jim, the plane hits. What's -- and I hope this isn't a terribly oversimplified question, but what happens to the building itself?
JIM DESTEFANO, NATL. COUN. STRUCTURAL ENGINEERS: Well, it's a structure. It's a tremendous impact that's applied to the building when a collision occurs, and it's clear that that impact was sufficient to do damage to the columns and the bracing system supporting the building. That, coupled with the fire raging and the high temperatures, softening the structural steel, then precipitated a destabilization of the columns. And clearly, the columns buckled at the lower floors, causing the building to collapse.
BROWN: So it is a combination of, as we see again, this extraordinary shot of the second plane hitting the tower, it is a combination of the impact of the plane itself, and then the fire that ensues, that causes these -- I don't know, are they called beams -- to buckle?
DESTEFANO: Yes, it's the columns. The vertical elements are columns, and those are the elements that are holding the whole building up, and those are the critical, vulnerable elements that clearly failed in a buckling mode from the high temperatures and the damage from the impact.
BROWN: Now, I'm not asking you to assign any blame to anyone about anything here, but just give me an idea if, in fact, you can design these buildings in such a way so that it does not -- this sort of thing does not happen, even in a catastrophic event.
DESTEFANO: It's very difficult, when you're designing a structure like this, to imagine all the scenarios of things that might occur to the building during its construction. It is my understanding that when this building was designed, one of the criterias that it was designed for was a direct hit from a 707. Clearly, planes are larger today, and it wasn't considered the effect of the aftermath fire and high temperatures that would have been applied to the structure subsequent to the collision, as we saw today.
BROWN: And to the best that you can, give me an idea of how long it will take for that building to be safe to go into. Because what we know is there -- or what we believe, at least, there are still people trapped in there. The mayor talked about a week that this rescue operation is going to take. Is that realistic?
DESTEFANO: I think it's very realistic, that what we've seen in other collapses, like L'Ambiance Plaza here in Connecticut, and the Hyatt Regency in Kansas City and the Oklahoma City bombing -- this takes a very long time to clear the rubble and find all the people that might be trapped underneath it.
BROWN: At what point, what has to happen before it is literally safe to send someone into that space?
DESTEFANO: I don't know that it will ever be safe. I think the rescue people that are in there trying to save people are very much at risk, as they always are in these kinds of disasters. That structures always -- when you have a pile of rubble like this, the structure is always somewhat unstable, so those rescue workers that are in there are at some risk. There's never a point where you can say this building is safe to walk into and start looking around.
