Last tower hit, first to fall.

[screembloodymurder]

Does anyone know if the towers were of identical design? Did the South tower suffer greater damage from impact? Was the fireproofing changed? On what floor did the collapse start? Did the 911 Commission Report have an explanation for this apparent anomaly?

[greyl]

1. The South Tower was hit at significantly higher velocity than

the North Tower. Additionally, the South Tower was hit lower than the North, meaning that more weight was stressing the damaged points of impact and fuel explosion. Some experts say that if the South Tower was hit slightly differently, it would have collapsed immediately after impact.
fwiw.

http://select.nytimes.com/gst/abstract.html?res=F50E11FF3A5A0C708EDDAB0894DA404482
http://www.caddigest.com/subjects/wtc/select/clifton/p1.htm

[screembloodymurder]

3. Thanks.

I had heard that the tower collapsed from the top down, but it sounds like that's not true.

[Bolo Boffin]

4. The South Tower might have fallen on impact if hit right??

Wow. As bad as that day was, it could have been much much worse.

[BootinUp]

5. I am trying to remember where I saw it

Someone had done a calculation that showed the lateral energy absorbed by the tower was right at the upper design limit for wind forces, might have been an old thread here. Your comment is quite scary.

[greyl]

7. It's at the pay link in my above post. Here's a free copy:

www.lafire.com/famous_fires/2001-0911_WTC/2002-1029_NYTimes-DataTrove/2002-1029_NYTimes-DataTrove.htm

[Sinti]

2. I think the story is that the corner damage, and damage going deeper

made the building more unstable from impact. The explanation I read actually made sense. 78th-84th floors were hit which is lower than the other, hence more stress on the undamaged support members, blah, blah, blah. I sure do wish the N. Tower had fallen first, the S. Tower had more people in it, including more firefighters.

[Applan]

6. The south tower was hit further down

This would mean that it would have much more weight pressing down on the damaged structure which would lead to higher stresses and therefore faster failure. Of course that is assuming that's what cause the towers to collapse.

[Name removed]

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[planeman]

9. The arrangement of the staircases was different.

If I am not mistaken,one of the staircases in the south tower ran outside the central portion in the core.This allowed some people to escape.
In the North Tower all 3 staircases were located in the central area of the core so when the plane hit it desroyed all 3 staircases severing these potential escape routes.

[Name removed]

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