Why Indeed Did the WTC Buildings Collapse?

Question

If the World Trade Center (WTC) towers were designed to withstand multiple impacts by Boeing 707 aircraft, why did the impact of individual 767s cause so much damage?

Since the WTC tower’s design engineer, John Skilling, said that he took airliner crashes and jet fuel fires in to account and then stated clearly that “the building structure would still be there”, why was NIST so sure from the start that fires brought down the buildings? Then, when NIST started to use Mr. Skilling’s words in their later presentations, why did they suggest this was only an anonymous view? Finally, in what places did NIST look for Skilling’s aircraft impact analysis?

Fires simply do not cause steel-frame buildings to collapse. That's one of the reasons why so many fire-fighters were killed in the twin towers on 9/11. No one had any reason to fear a total collapse.

Please respond back with scientific findings or other proofs as to why those towers collapsed in the manner that they did.

Answer 1

Fires don't. Unless they are started with 20,000 gallons of high octane jet fuel pouring down elevator shafts.

Answer 2

Remember that with any engineering design, they can "factor in" possible events, but they are only ever going to be very good estimates - considering that until 9/11 nobody had ever actually flown a fully laden jetliner into a skyscraper building!

Now I'm not a Structural Engineer, but, from the evidence and information on the WTC disaster, I can make some informed guesses of my own.

The planes didn;t just fly through the buildings, and then toddle off. They both flew in, and then exploded.

This explosion would not only have ripped the plane apart, but also exploded up, down and to the sides. the steel frames where it entered would have been destroyed, as well as the floors above and below, with debris fallind down, destroying and damaging other floors.

The explosive power of a jetliner would be pretty big - and that explosion, combined with the fire, would have fatally compromised the steel structure of the buildings, I would imagine.

Nothing is ever totally indestructable. In1972, when the WTC was built, it was state of the art. Age also plays a part, and WTC was about 30 years old when it was hit.

For the rest of your question - why not do some research yourself and look at the NIST report for your answers. I'm sure it's available to the public.

Answer 3

To read The Final Report of the National Construction Safety Team on the Collapses of the World Trade Center , prepared for the National Institute of Standards & Technology , - more than 200 staffers & contractors conducted interviews with over 1000 people who were on the scene ; or involved w/ the design , construction & maintenance of the WTC ; analyzed some 236 pieces of recovered steel ; lab tests & computer simulations ; accumulated 7.000segments of footage pix from 185 photogs over 3 yrs. & $24 million -go to http://wtc.nist.gov/pubs
The Towers withstood the impact . However, one of the main causes for collapse was the fact that the dislodged fireproofing ( caused by the planes ) & fires , weaked the core columns & caused the floors to sag .

Answer 4

Apparently he didn't. Did he take building gas lines into account - there were a lot going up to the top? Did he take deliberate crashes with fully fueled planes into account and what size plane and what type of fuel? Did he take loss of support structures from the crash and fire weaken steel into account on the 80th floor with twenty floors of concrete and steel sitting on top of it? Did you do your homework or are you simply parroting a website? Do you know that wood beams withstand fire damage better in homes which is why insurance companies advise against using steel beams in your home - steel beams bend and sag when hot? Do you understand tensile strength and structural integrity once steel is heated? Actually to be blunt, do you understand anything or are you another liberal or conspiracy parrot?

Answer 5

Many documentarys have been aired, including interviews with those who designed and built the towers in which it was proven that due to the huge amount of jet fuel the fire burned so hot that the steel beams turned to a play-doh type of consistency, causing the collapse. One of them aired on the History Channel just last night (9/10).

Answer 6

Oh me, oh my, whatever could have been the cause of the WTC buildings collapse? It sure couldn't have anything to do with those huge aircraft that all those witnesses saw crash into the buildings, could it? Naw, that's would just make too much....sense. MUSTA been a HUGE government conspiracy. That's the only possible answer.

Seriously, every point you brought up has been answered by more then a few people who know what they're talking about.

Answer 7

The plane hit,

it blew away alot of the fire resistance coating on the steal.

the heat weakened the steal.

the weight of the building above this point made the building above to far down onto that floor. The weight of this fall and force, continued to cause the floor below and then below.

This has been studied and was the cause.

And of course the terrorist could have had other material onthe plane in storage area that we will never know, since it blew up.

And of course they did not think of a plane hitting at the speeds it did, since they would have beleived the pilot would be either landing or taking off or trying to slow down or in a stall. Not flying full speed into the building.

It happened get over it, Read the mechanic digest review of it, it sorta proves it all.

Answer 8

I don't have a source for this because it is just in my memory; but, I remember on 9/11 watching CNN report on it. Everybody was confused and everything was chaotic... trying to figure out what had just happened.

A reporter had gotten a hold of somebody's camcorder recording of one of the planes from a bottom view. The CNN reporter was saying... ' it appears that something was attached to the bottom of the plane..' while showing the clip.

It did look like it had some big black thing attached to the bottom of it. That's all I know. I have never researched it.

Answer 9

There is a great article in Time magazine that covers this irrational conspiracy theory. People want to feel that something this grand and catastrophic could not happen by chance. By believing in a conspiracy, it helps them feel safer - that the world isn't just random - buildings don't just fall on themselves under stress (tremendous in this case) - people can't orchestra such horror and succeed (as they did).

As for the floors below exploding before the upper floors fell - it's called an air pressure change in the building blowing windows out - similar to what happened during a tornado - the air pressure blows out windows and the building implodes - that's why you see what you see in the photos.

Answer 10

you answered your own question in first paragraph............towers were designed to withstand impact of 707, not 767's seriously, i heard that design was for impact of 707 at a speed of 180 knots or near that.........the 767's were going close to or over 500......meaning where a pilot was trying to miss the buildings, not fly as fast as possible with intent to hit......quite a bit of a difference, that and the amount of fuel dumped and burning and where the buildings were hit all made the difference............or you can believe the conspiracy theories and go with the planes carrying high explosives or better yet, the one where the planes were carrying missles..........i love that one.............yahoo

Answer 11

If I recall correctly, jet fuel burns at about 850C. Steel doesn't melt until well above that, but structural steel loses more than half it's strength at about 630C - well below the temperature of the fires. Given that, I don't think it surprising that the towers collapsed.

I remember hearing the designer say that they had planned for airplane crashes. Heck, the Empire State Building has been hit multiple times. I don't remember him saying that they had planned for the fires that resulted, though. It seems to me he said the exact opposite. Do you have a reference for that?