7 World Trade Center collapse

July 3, 2006 1:21 AM

Why did 7 World Trade Center collapse on 9/11? A friend thinks that its collapse was caused by our own government, but I can't say I believe that.
posted by jimmy to education (36 comments total)

I heard planes crashed into the buildings.
posted by zackdog at 1:27 AM on July 3, 2006

Just tell your friend to read the official reports first.
posted by Psychnic at 1:38 AM on July 3, 2006

I heard planes crashed into the buildings.

No plane crashed into 7 World Trade Center. Again, that's 7 World Trade Center.

Once more, for clarification: 7 World Trade Center.

I believe that 7 World Trade Center collapsed as an indirect result of the destruction of WTC 1 and WTC 2. I'm just wondering if anyone knows exactly how it happened.
posted by jimmy at 1:40 AM on July 3, 2006

Psychnic, he's read the fifth part of the report ("Reconstruction of the Fires in the World Trade Center Towers"), and offers this critique of it in response as the main basis of his theory.
posted by jimmy at 1:47 AM on July 3, 2006

There was a big thread on the demolition theory a few months ago.
posted by teleskiving at 1:57 AM on July 3, 2006

public, I'm not looking to argue with anyone, so I'm not sure why you're getting out the popcorn. I just need a definitive answer as to why the tower collapsed from someone who knows more about this subject than I do. If you don't have anything substantial to offer, then please leave.

teleskiving, that might be exactly what I was looking for. Thank you.
posted by jimmy at 2:03 AM on July 3, 2006

In three words, it burned down.

On another day, someone would probably have put the fire out out, but they didn't.
posted by AmbroseChapel at 2:08 AM on July 3, 2006

Wait, no it wasn't. That thread was a mess.
posted by jimmy at 2:09 AM on July 3, 2006

But there are some good links in there, and I'm working on sifting through them.
posted by jimmy at 2:11 AM on July 3, 2006

Popular Mechanics on the subject.
posted by AmbroseChapel at 2:17 AM on July 3, 2006

Cheap concrete. Saves the contractors quite a sum.
posted by IronLizard at 2:24 AM on July 3, 2006

I just need a definitive answer as to why the tower collapsed from someone who knows more about this subject than I do.

This has been argued to death in many posts over the years now. The fact that people are answering your question by giving you links to MeFi threads alone proves this.

There isn't a definitive answer since conspiracy theorists will always come up with some crazy possibility based on whatever it is that we don't know for certain about what happened. If you want to believe the official report, then do. The writing of it presumably involved people knowledably in areas such as engineering and more specifically building demoltion.
posted by public at 2:56 AM on July 3, 2006

If you don't have anything substantial to offer, then please leave.

The point is that this has been hashed out here again and again.
posted by CunningLinguist at 6:25 AM on July 3, 2006

Like here for example. And here.
posted by CunningLinguist at 6:32 AM on July 3, 2006

There was a lot going on beneath ground; shops etc... I'd always presumed that the buildings shared foundations. Or that the collapse of the first two towers weakened the foundations of number 7.
posted by popcassady at 7:05 AM on July 3, 2006

There's no point in your looking for a definitive answer, because your friend has already picked one. Nothing you can say is going to change their mind.

No level of evidence can ever convince a conspiracy theorist, for the same reason that there are no statistics that can dissuade a numerologist. Every example will have a counter-example, and the truth will always be less compelling than fantasy.

A better way to approach the matter would be this: your friend is demonstrably gullible, and equipped with a marvellously suspicious nature. Surely there's some way you can turn this to your financial advantage? I suggest something along the lines of products that might protect his/her precious bodily fluids from gov't control (structured water perhaps? Guaranteed to remove the tricky nanospores that coat every penny, and only $10 a dose!)
posted by aramaic at 7:47 AM on July 3, 2006

Official reports will point to uncontrolled fires that were not addressed due to the main crisis occurring elsewhere at the WTC site.

I have friends who, after reading articles or viewing things like Loose Change will claim that there is undoubtedly a conspiracy at play. Put Occam's Razor and your knowledge of human nature and morality to use to think about this: If there was a controlled demolition of a building, who would have to have had knowledge and have been complicit? The owner of the building, the New York Police and Fire Departments, the Federal Government, and the congressional and executive branches of the government? At least a fair number of these people. Although some people will claim it was incomplete, there was an investigation into the events of September 11, 2001. If anyone was withholding knowledge, then anyone overseeing them ignored it. And the superiors of those individuals.

Despite a lack of faith in government, can anyone with good conscience claim that they believe there was an active conspiracy to destroy property and kill civilians? I feel that we're being served by corrupt and incompetent individuals that have questionable motivations at some points, but I don't believe that such a far-reaching conspiracy wouldn't have at least one Deep Throat-type character, if not the outrage of tens or even hundreds who would have had to know.
posted by mikeh at 8:04 AM on July 3, 2006

structurally speaking; the immense heat caused by the plane crash from burning fuel to other fire sources caused the steel framed constructed building to collapse in the effected parts, the building was not fire rated to withstand temperatures that high. From there on the rest of the building collapsed under it's own weight. Doesn't get any simpler than that.
posted by convex at 8:33 AM on July 3, 2006

there was an active conspiracy to destroy property and kill civilians?

There was, by anybody's lights. Whether you think the conspiracy exclusively involved al Qaeda or not is another matter, but it's hard to see what distinguishes "conspiracy" from "non-conspiracy" here.
posted by sonofsamiam at 8:40 AM on July 3, 2006

I think 7 World Trade Center most likely collapsed due to a combination of damage from debris falling from the two big towers, plus fire that was fueled by the 42,000 gallons of diesel fuel in the building. Here's a copy of a March 2002 New York Times article that explains the theory for the collapse. (It's on a conspiracy site; there's a link to the Times article.) The fire weakened transfer trusses (this unrelated article has a pretty good description of what transfer trusses do).

Videos of the 5:28 p.m. collapse of 7 World Trade lend vivid support to the truss-failure theory. Roughly 30 seconds before the building goes down, a rooftop mechanical room starts to disappear, falling into the building's core. Then a second larger rooftop room sinks. The building then quickly collapses.

Both rooms were above sections of the building held up by the trusses. Other video evidence shows fire concentrated in the floors containing the trusses and the fuel tanks.

There were fuel tanks on the fifth, seventh, and eighth floors, and the preliminary FEMA report says, "Loss of structural integrity was likely a result of weakening caused by fires on the 5th to 7th floors." The building was 47 stories tall, so when the trusses collapsed, it was like dropping a 40-story building on top of a seven-story building, which might explain why the building fell straight down. (Note: I am not a structural engineer.)

Here's a conspiracy page with videos and a nifty animated GIF of WTC7's collapse, which claims that "all of the load bearing supports would have had to fail at exactly the same time" (without backing the assertion up).

A lot of the conspiracy theorists cite Steven E. Jones, who's a Physics and Astronomy professor at BYU (he coined the term "cold fusion"). He also thinks Jesus travelled to Central America. I think structural engineers would be more reliable.
posted by kirkaracha at 8:52 AM on July 3, 2006

fueled by the 42,000 gallons of diesel fuel in the building.

That is correct. I witnessed it from about 1000 feet away. The fire in that building just kept getting bigger and bigger for hours. The anchors on the curtainwall melted and the facade slid off like a discarded dress.

It didn't collapse in the same sense that the towers almost vaporized, it just kind of slumped into a 10 story pile of smoldering debris that continued to burn for months.
posted by StickyCarpet at 9:08 AM on July 3, 2006 [3 favorites]

"all of the load bearing supports would have had to fail at exactly the same time"
The folks behind that conspiracy theory express surprise that the building falls straight down instead of falling like a tree. Osama bin Laden, in the post-911 video where he's gloating over the attacks with some sheik, had the same view; he said he had been surprised the towers fell straight down instead of sideways. The fallacy in this thinking is that gravity dictates things fall straight down, unless some greater force causes a sideways fall. When a building falls because the critical structural members get progressively weaker in a fire, there is no significant sideward force in the picture. A tree falls sideways because the rigidity of the trunk is far stronger than the effect of gravity, so it withstands any tendency to collapse straight down. But most buildings lack the rigidity that would be required for such a fall. It acts more like a stack of toy blocks -- try to make the stack fall sideways by tilting the bottom block, and the stack will just collapse downward on your hand. In a building such as 7 WTC, the fire likely caused a domino effect -- the first support column to fail put a lot of stress on the adjoining ones, which were also losing strength due to the heat; they collapsed and put stress on the next ones, etc. This would happen within a very short period of time -- seconds. So in effect, yes, they did fail at (virtually) the same time.
posted by beagle at 9:44 AM on July 3, 2006

A comment on the structural engineering front and the claim "all of the load bearing supports would have had to fail at exactly the same time".
Imagine 10 load bearing columns each rated to hold 10 tons, holding a structure that is 80 tons. This gives each column 2 tons of overhead. Now imagine a fire that begins to weaken the load bearing columns. Say 4 have been weakened by 5% (can support 9.5 tons), 3 have been weakened by 10% (can support 9 tons), 2 by 15% (8.5 tons), and 1 is at the failure point (8 tons). As that column fails, the load it was holding is now transferred to the other columns. So now 9 columnts must support 80 tons (or around 9 tons each), this increase in load causes 2 other columns to fail pretty much immediately, and now 7 columns must support 80 tons. This is greater than any column can support and a catastrophic collapse ensues. All columns *appear* to fail simultaneously, even though only one column actually did fail, the weakened structure just couldn't handle the transfer in load.
posted by forforf at 9:47 AM on July 3, 2006

Rigorous Intuition: The Coincidence Theorist's Guide to 9/11
posted by hortense at 10:42 AM on July 3, 2006

Nobody died in WTC 7 so the issue of its collapse isn't of the greatest importance. The Final Report on its collapse hasn't even been issued yet. There are theories related to a combination of fire damage and loss of structural integrity resulting from debris of the collapse of 1 and 2. This article gives some preliminary analysis. But the importance of WTC 7 being demolished is questionable. Why would the government take it out instead of the nearby Post Office? Or why not other more important targets in NYC?
posted by JJ86 at 11:31 AM on July 3, 2006

Thanks, everyone, for the posts so far. For those concerned, you can be sure that I have no intention of dragging this out into a pointless argument by refuting these links with my friend's arguments. The comments in this thread have provided a decent number of issues to bring up with him the next time I see him, and I'm interested in anything else that may be out there.
posted by jimmy at 11:54 AM on July 3, 2006

not sure if this has been said (sue me, thats a lot to read just to throw out an answer), but I saw footage of the WTC owner guy talking about how falling debris from the towers had started fires in building 7 so they "pulled it". Not sure if the official story has changed...
posted by Tryptophan-5ht at 12:17 PM on July 3, 2006

Awesome link, hortense.
posted by nevercalm at 1:43 PM on July 3, 2006

This page has a video clip from the September 2002 PBS documentary America Rebuilds of Larry Silverstein (the owner of WTC7) saying:

I remember getting a call from the, er, fire department commander, telling me that they were not sure they were gonna be able to contain the fire, and I said, 'We've had such terrible loss of life, maybe the smartest thing to do is pull it.' And they made that decision to pull and we watched the building collapse.

On September 9, 2005, a spokesman for Silverstein Properties issued a statement:

In the afternoon of September 11, Mr. Silverstein spoke to the Fire Department Commander on site at Seven World Trade Center. The Commander told Mr. Silverstein that there were several firefighters in the building working to contain the fires. Mr. Silverstein expressed his view that the most important thing was to protect the safety of those firefighters, including, if necessary, to have them withdraw from the building.

posted by kirkaracha at 2:25 PM on July 3, 2006

It ultimately comes down to whether you accept or reject the official explanation that WTC 7 fell due to a combination of structural damage from falling debris and fires in the building. Personally, I find the alternative theories to be exceedingly farfetched.
posted by KirkJobSluder at 3:08 PM on July 3, 2006

It will be very interesting to see the final WTC 7 report, since there are plenty of questions reasonable people could ask about the event.

A much more interesting consideration is the number of deaths caused by highway fatalities after 9/11, since mnay people chose to drive rather than fly. I don't know if anyone has collected numbers, but I suspect that far more people died as a result of driving (rather than flying, due to terror fears) than died in all of the 9/11 attacks.

We haven't seen any further terrorists attacks because Osama's smarter and richer brothers told him to buy GM and Ford stock. That way, he can kill americans and profit at the same time. (I'm making this part up)
posted by b1tr0t at 5:53 PM on July 3, 2006

b1tr0t: Almost 40,000 people die in traffic accidents every year in America.
posted by subclub at 10:02 AM on July 4, 2006

I know, but how many more died as a result of post-9/11 fear of flying?
posted by b1tr0t at 11:14 AM on July 4, 2006

I see what you're asking, b1tr0t, but you're assuming that people drove instead of flew. Perhaps they stayed home instead.
posted by raedyn at 12:58 PM on July 4, 2006

Nobody seems to address what I think is the elephant in the room: Why and how do you perform a controlled demolition without anyone realizing, in what is already a war zone of fire, smoke and debris, with all the world's media watching -- and why would you want to hide the fact afterwards?

You don't need Occam's Razor to see that the complexity of this argument collapses (pun intended) under its own weight. You would to pay off a lot of people to keep them quiet, including everyone that FEMA and NIST have access to. The conspiracy theory also neglects a simple problem: If the city and the owners of the building had decided that they needed to demolish the building, they could certainly have done (or at least attempted) this, without any kind of secrecy; but they didn't need to demolish it. I don't understand -- perhaps the building supposed to house secret papers documenting how 9/11 was planned by the Bush administration? Or is the idea that WTC 7 was demolished because its collapse was needed to provoke the American people into rallying against the terrorists?

As for the technical aspects, the couch potatoes crying conspiracy cannot possibly know anything about demolition. It is difficult, error-prone and time-consuming to tear down a building in a controlled way; you don't just "pull down" a building with a shrug and a wave of the old magic TNT wand, unless you want to hurt people and property and/or a big mess on your hands. Unlike the most successful controlled demolitions, the collapse of WTC 7 wasn't symmetric at all: the building slid diagonally into the north building, damaging it.
posted by gentle at 3:15 PM on July 4, 2006

Or the other elephant: if you're going to do controlled demolitions, what do you need the planes for? Al Qaeda had tried to blow up the World Trade Center in 1993. Even if it was an inside demolition job (which I do not believe), why not just do that and frame al Qaeda for it?

The whole conspiracy theory angle is too over-the-top. Supposedly the government's sinister agents shot a missile into the Pentagon, shot down Flight 93, planted explosives into WTC1 and WTC2 and flew planes (or drones) into them, planted explosives in WTC7 and "pulled it," and took the real people on the real planes and made them disappear somewhere. It's too elaborate.
posted by kirkaracha at 6:37 PM on July 4, 2006