Why the WTC Towers Fell - on PBS
Why the WTC Towers Fell - on PBS
(OP)
For U.S. (and perhaps some Canadian) members of Eng-Tips members: here is an interesting program on the collapse of the World Trade Center towers. It is based on the ASCE investigation and report. It's a good place to direct your curious non-engineer friends who want to understand why the towers fell. Here's the link for additional information as well as the press release I received by email:
http://www.pbs.org/nova/wtc/
_____________________________________________________________________
NEXT ON NOVA: "WHY THE TOWERS FELL"
http://www.pbs.org/nova/wtc/
Broadcast: September 9, 2003
(NOVA airs Tuesdays on PBS at 8 p.m. Check your local listings as
dates and times may vary.)
For most Americans, the image of the collapse of the World Trade Center
towers was not only a scene of unforgettable horror, it was a moment of
unimaginable consequence. Who could have guessed that a steel behemoth
of such size and strength -- a building so massive that it had its own
zip code -- could actually be reduced to 150 feet of dust and rubble? In
the Emmy-Award winning "Why the Towers Fell," NOVA reports on the
findings of the government-mandated American Society of Civil Engineers
(ASCE) investigation.
Here's what you'll find online:
Towers of Innovation
A basement like a bathtub. A building like a tube. An
elevator system like a subway system. These are just some
of the engineering marvels that made the quarter-mile-tall
World Trade Center possible.
The Collapse: An Engineer's Perspective
In this interview, Dr. Thomas Eagar, a professor of materials
engineering and engineering systems at MIT, explains how and
why the Twin Towers survived the initial impact -- and how
and why they likely failed in the end.
Above the Impact: A Survivor's Story
Brian Clark was one of only four individuals to escape either
tower from above the floors where the planes struck. Here, Clark
tells his riveting, vividly personal tale.
Outfitting Firefighters
The firefighters that raced up the stairwells of the doomed
towers carried several dozen pounds of equipment, everything
from axes and turnout gear to thermal imaging cameras and self-
contained breathing apparatuses. In this feature, equip fire-
fighters for a high-rise response.
The Structure of Metal
Explore metal at the atomic level and discover how it's structured,
why it bends, and what happens when it heats up.
NOVA News Minutes
Watch news clips related to the program.
Plus Resources.
http://www.pbs.org/nova/wtc/
_____________________________________________________________________
_____________________________________________________________________
Thank you for visiting NOVA Online. We welcome your questions, comments,
and feedback. You can send a message directly to nova@wgbh.org, or use
our feedback form at http://www.pbs.org/nova/feedback/
You are subscribed to the NOVA Online mailing list. To unsubscribe, go
to http://www.pbs.org/nova/mailing/unsubscribe.html -- or send an e-mail
to majordomo@franz.wgbh.org and, on a line by itself in the message,
type: unsubscribe nova-online
Major funding for NOVA is provided by the Park Foundation, Sprint, and
Microsoft.
_____________________________________________________________________
http://www.pbs.org/nova/wtc/
_____________________________________________________________________
NEXT ON NOVA: "WHY THE TOWERS FELL"
http://www.pbs.org/nova/wtc/
Broadcast: September 9, 2003
(NOVA airs Tuesdays on PBS at 8 p.m. Check your local listings as
dates and times may vary.)
For most Americans, the image of the collapse of the World Trade Center
towers was not only a scene of unforgettable horror, it was a moment of
unimaginable consequence. Who could have guessed that a steel behemoth
of such size and strength -- a building so massive that it had its own
zip code -- could actually be reduced to 150 feet of dust and rubble? In
the Emmy-Award winning "Why the Towers Fell," NOVA reports on the
findings of the government-mandated American Society of Civil Engineers
(ASCE) investigation.
Here's what you'll find online:
Towers of Innovation
A basement like a bathtub. A building like a tube. An
elevator system like a subway system. These are just some
of the engineering marvels that made the quarter-mile-tall
World Trade Center possible.
The Collapse: An Engineer's Perspective
In this interview, Dr. Thomas Eagar, a professor of materials
engineering and engineering systems at MIT, explains how and
why the Twin Towers survived the initial impact -- and how
and why they likely failed in the end.
Above the Impact: A Survivor's Story
Brian Clark was one of only four individuals to escape either
tower from above the floors where the planes struck. Here, Clark
tells his riveting, vividly personal tale.
Outfitting Firefighters
The firefighters that raced up the stairwells of the doomed
towers carried several dozen pounds of equipment, everything
from axes and turnout gear to thermal imaging cameras and self-
contained breathing apparatuses. In this feature, equip fire-
fighters for a high-rise response.
The Structure of Metal
Explore metal at the atomic level and discover how it's structured,
why it bends, and what happens when it heats up.
NOVA News Minutes
Watch news clips related to the program.
Plus Resources.
http://www.pbs.org/nova/wtc/
_____________________________________________________________________
_____________________________________________________________________
Thank you for visiting NOVA Online. We welcome your questions, comments,
and feedback. You can send a message directly to nova@wgbh.org, or use
our feedback form at http://www.pbs.org/nova/feedback/
You are subscribed to the NOVA Online mailing list. To unsubscribe, go
to http://www.pbs.org/nova/mailing/unsubscribe.html -- or send an e-mail
to majordomo@franz.wgbh.org and, on a line by itself in the message,
type: unsubscribe nova-online
Major funding for NOVA is provided by the Park Foundation, Sprint, and
Microsoft.
_____________________________________________________________________

Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.






RE: Why the WTC Towers Fell - on PBS
I remember seeing a Nova on the WTC towers either much earlier this year or late last year.
TTFN
RE: Why the WTC Towers Fell - on PBS
Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.
RE: Why the WTC Towers Fell - on PBS
As a structural engineer myself, I consider the solution for the buildings to have been an elegant and clever design and the engineer did absolutely nothing wrong.
Perhaps when the program has aired Focht3 and others could post with a summary of the findings and we could discuss the facts and compare with the documentaries others have seen.
Regards
RE: Why the WTC Towers Fell - on PBS
I fully agree with some of the posters here that it was not in the scope of design of the towers to include terrorism provision at that time. The structural engineer is therefore not to blame. We now live in a world different to the designer of the twin tower and we have to think of the terrorist risks.
I have been puzzled by only one feature on the collapse of the twin tower. Are the terrorists really that clever or it was down to pure luck? They had to have to access to world experts on structural engineering, tall buildings design, material science, aeroplane design, daynamics and combustion engineering to pull it off as they did. I know Binadin is just a huge civil engineering contractor in Saudi but I am not convinced he had the necessary know how. Seems to me it was Binadin's own mistake because of his lack of engineering appreciation to understand the consequence. That action led to thousands of his followers died and his base uprooted in Afganstan. He can no longer openly exists anywhere in this world and his religion suffers a bad name for generations to come.
RE: Why the WTC Towers Fell - on PBS
RE: Why the WTC Towers Fell - on PBS
I suspect we all have a much healthier respect for the potential consequences of fire, particularly where a large pool of accelerant is involved -
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RE: Why the WTC Towers Fell - on PBS
My recollection is the exact opposite. I remember a private videotape made in Afghanistan and recovered from there after the war, in which OBL was seen sitting around with some other guys and saying (according to the translation) that he had predicted that the towers would fall after the impacts, and that his expertise in the family construction business enabled him to do this. Of course, whether he had actually made such a prediction, or was just being wise after the event, is a debatable point.
RE: Why the WTC Towers Fell - on PBS
I was surprised by the collapse too. I think it would be right to say if the planes had very little or no fuel left then the two towers should have stood because the fire risk would be low.
The progressive collapse within the central core, pulling the outer shell neatly to the inner is unseen and unheard before the disaster. I doubt if any structural engineer has set out to engineer a collapse intentionally, for all intents and purposes, within the footprint of such a tall building.
RE: Why the WTC Towers Fell - on PBS
We are both right - and wrong...
I found the following link to NPR's web site (after a Google search for 'Osama world trade center collapse videotape'):
http://www.npr.org/news/specials/response/investigation/011213.binladen.tape.html
An excerpt from that site says,
According to a translated transcript issued by the Pentagon, bin Laden says the attacks on the World Trade Center did more damage than expected. "...we calculated in advance the number of casualties from the enemy, who would be killed based on the position of the tower," he says, according to the transcript. "We calculated that the floors that would be hit would be three or four floors. I was the most optimistic of them all. (...Inaudible...) due to my experience in this field, I was thinking that the fire from the gas in the plane would melt the iron structure of the building and collapse the area where the plane hit and all the floors above it only. This is all that we had hoped for."
I can't wait until we catch that guy -
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RE: Why the WTC Towers Fell - on PBS
In any case, the collapse was un-anticipated, since the structure was designed to handle a 707 impact with margin. Had OBL thought that the towers could be brought down and or thought through the amount of potential damage, he would have designed for a lower strike point on the tower, i.e., down to possibly the 40th floor. This would have been above the capabilities of any ground-based fire-fighting equipment, while maximizing the possibility of causing the towers to weaken and fall sideways, which would have increased the potential damage.
It's more likely that OBL thought that the towers would pancake down to the impact site and no further, which would have left two damaged towers as a constant reminder of his power. It would have taken much more than 8 months to clean up and would have taken many more months to repair or rebuild. I suspect that a full collapse was undesirable, since that would have meant a relatively quick clean up and no obvious reminder of his deed in the skyline.
TTFN
RE: Why the WTC Towers Fell - on PBS
Well, if he was really smart enough to figure out that it was definitely going to collapse "all the floors above", he should have been able to deduce that the whole tower would subsequently collapse - it would seem to me that this would be the simpler part of the analysis. Perhaps he was just referring to the local part of the floors directly above the impact - you'd have to be a real expert in Arabic translation to know.
RE: Why the WTC Towers Fell - on PBS
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RE: Why the WTC Towers Fell - on PBS
When I first glanced at your reply I thought it said "any fool can be an architect" .... perhaps something deep and Freudian there ....
RE: Why the WTC Towers Fell - on PBS
http://www.sumeria.net/politics/bushknew/ghostriders2.html
RE: Why the WTC Towers Fell - on PBS
RE: Why the WTC Towers Fell - on PBS
Good job we engineers base everything on facts and experience.
RE: Why the WTC Towers Fell - on PBS
One thing that occurs in the videos of the WTC after the planes hit is that one can see the floors failing. This hasn’t been mentioned in any of the commentary on the collapse that I’ve seen.
The failure of the floors can be readily ascertained by the “jets” of dust and debris being ejected from the tower at a point that appears to 20 to 30 floors below the mass of the failed section above the impact.
I think the plan was to duplicate the plane crashing into the Empire State Building and as mentioned above leave a symbol in the sky. But one still has to wonder as Osama had a lot experience in construction and probaly engineering help. Atta was an Architectural student. What type projects did he work on in school.
RE: Why the WTC Towers Fell - on PBS
RE: Why the WTC Towers Fell - on PBS
Besides that, if someone is capable enough to design such an intelligent move, don't you think he would be wise enough to forsee the post-accident effects. See this event in a bigger prospective. Regards
RE: Why the WTC Towers Fell - on PBS
http://www.guardian.co.uk/comment/story/0,3604,1036571,00.html
RE: Why the WTC Towers Fell - on PBS
I agree that we should stay away from politics in this forum. Like youself I had personal experience with his company and thereby have an appreciation of what he could do in term of engineering. I am glad that you confirm independently my assessment of his influence on your country. Not many people realize the reason why he is so well supported.
I spend all my life working with engineers of all nationalities and religions, a large portion of it in the Middle East. Engineers can always agree and disagree because we respect each other's wiew.
I am glad to see a diversity of views in here.