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NIST Releases Report On WTC 7 Collapse
Posted by
Soulskill
on Sun Aug 24, 2008 12:15 PM
from the play-nice dept.
from the play-nice dept.
photonic writes "After three years of study, the National Institute of Standards and Technology (NIST) finally released its report on the collapse of World Trade Center building 7. The main conclusion is that the building came down due to fire, not due to debris damage or some conspiracy demolition team. The fire started pretty small after the collapse of WTC 1, but was left to burn several floors out completely. The important finding is that the collapse was triggered by thermal expansion of beams, which could detach asymmetrically loaded girders from the main columns. Some limited pancaking of floors then caused a lack of lateral support and buckling of a single column. This triggered the failure of the entire core of the building, which finally fell down as a single piece. Crackpot theories can be discussed elsewhere; please limit the discussion to the science here. All documents can be found at NIST's WTC page, which read like a porn magazine for finite element junkies. Simulation movies are also available. And yes, they used Beowulf clusters to do the simulations, some of which lasted for several months."
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You've GOT to be kidding! (Score:5, Funny)
Re:You've GOT to be kidding! (Score:5, Funny)
I think he meant to say
Parent
Why is the crackpot theory not debunked yet? (Score:5, Funny)
If someone left a crackpot burning, couldn't that have started the fire in the first place?
Ipso diabolico facto nonsensicalico.
These guys have resources. It could be quite damaging to be caught with a smoldering crackpot.
Ergo, they crash a plane into the building to cover it all up.
Sheeple, the answers are RIGHT IN FRONT OF YOU, just light them up and breathe deeply.
Parent
Re:You've GOT to be kidding! (Score:5, Insightful)
Welcome to the wonderful world of self-confirming delusions, wherein you need never admit you're wrong.
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Imposter! (Score:5, Funny)
Crackpot theories can be discussed elsewhere; please limit the discussion to the science here.
What site is this, and what has it done with Slashdot
Re:Imposter! (Score:5, Insightful)
Crackpot theories can be discussed elsewhere; please limit the discussion to the science here.
What site is this, and what has it done with Slashdot
Well, for sure Digg [digg.com] is one of the places where this is happening, some idiots over there get +100 for the most ridiculous comments. What this has done to Slashdot? I hope they drew away some of the trolls from here...
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Wake up sheeple! (Score:5, Funny)
Zombies obviously did it.
Re:Wake up sheeple! (Score:5, Funny)
Let's leave McCain out of this one.
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Erm... (Score:5, Funny)
Crackpot theories can be discussed elsewhere; please limit the discussion to the science here.
You must be new here.
Unpossible! (Score:5, Funny)
Re:Unpossible! (Score:5, Informative)
Um, fires can pretty much bring down every building without some sort of suppression.
The sole exception is concrete, which can leave a hollow shell. Of course, no one on earth can build a 47 story concrete building.
Any building with steel as part of the support, on fire long enough, is eventually going to see that steel buckle, which will bring down the building. You can't just let tall buildings burn and then walk in the next day with new paint and furniture.
When they build steel buildings, they spray insulation on the steel to keep it intact during fires. For the WTC7, that was something called 'Monokote', which is rated for three hours for steel columns. (There is an entirely different 'Monokote' which is just a kind of plastic shrink wrap. Don't get confused.)
This would have been more than enough if the fire-suppression systems had been working, but they were not. It is also why the firefighters pulled out when they did...enough of the steel had started to buckle that the building was listing to the side.
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Re:Unpossible! (Score:5, Insightful)
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Crackpot theories can be discussed elsewhere (Score:5, Funny)
Wait a damn minute, here! (Score:5, Funny)
Asking Slashdot readers to stick to science, refrain from discussing conspiracies, AND taking the fun out of a beowulf cluster reference?
This submitter is a black belt troll and you all know it!
As to crackpot theories... (Score:5, Insightful)
Several things strange here (Score:5, Insightful)
First, I need to say a few things to inoculate myself from being labeled one way or the other:
1. The concept of a "conspiracy theory" is flawed, and is simply a cop out. There is no such thing as a conspiracy theory. There are just good and bad theories. Labeling an idea a "conspiracy theory" is just a form of jingoism and does nothing to increase the flow of ideas. Labeling something a conspiracy theory is a brilliant tactic to bury an idea as it takes advantage of herd mentality. Judge an idea by its merit and not by its label. Here on Slashdot extremely brilliant and extremely stupid ideas are posited all the time, so why now are we disallowed to discus a certain set of ideas? I thought there was a strong freedom/libertarian mindset here...
2. If you examine history, conspiracies are actually the norm and not an aberration. Look at Rome, or the times of Shakespeare, or Nazi Germany, or the French revolution, etc etc. Look at the behavior of the current administration of the United States and say there haven't been conspiratory behaviors with a straight face. All a conspiracy means is that more than one person plans together to do something secretly. That happens ALL THE TIME, whether criminally or not.
3. As Slashdot readers many of you consider yourselves to be scientifically minded and aware of logical fallacies. Why does this mindset breakdown when it comes to politically charged events? You are labeling people nut cases and tinfoil hat wearers and conspiracy theorists the same way people were labeled communists during the McCarthy era. The ad hominem attacks are relentless.
4. In light of the awareness that several agencies in the US with billions of dollars in funding and specific programs for controlling the flow of information DO exist, wouldn't you think that Slashdot, a hub of meme flow on the internet, would be a specific target of operations? Opinions are manipulated on the net regularly. You only have to look at China with their "wangyou" (internet friends) that are paid 50 cents chinese for each message they post that supports a certain agenda. The manipulation in the US is much more subtle. Teams of PhDs and psychologists know what buttons to press to get a certain response out of a self-admittedly obsessive compulsive crowd of nerds.
5. Building 7 was never hit by an airplane. The owner of the building admitted to it being demolished, then reneged his statement. There are videos of reporters describing building 7's fall while it is still standing in the background. It took SEVEN years for investigators to come up with a reason for the building to fall the way it did. Is it possible that the SEVEN years were spent honing a story plausible enough to convince even the most skeptical people of it's truth?
6. Unless you've visited the site of the building and done your own scientific measurements, everything you know comes from suspect media sources. This relates to point 3 above. I freely admit I don't know the truth of what happened due to this single fact.
In summary: Don't buy into either side of the story. There are plausible explanations for it being due to fire, but there are equally plausible explanations to it being due to malicious intent. Don't follow the herd - a certain subset of humans are purely pragmatic and will do whatever it takes to gain money or power.
PLEASE PLEASE refer to the last 5000 years of history and don't make the mistake of thinking that somehow right now things are different and innocent.
LS
Re:oh ok (Score:5, Insightful)
And your point is? It's a common misconception that random events don't or can't look very neat and tidy. One of the common mistakes people make when faking random data is to make it look too random. Meaning they don't have enough places in the data which appear to be non-random.
The way that a skyscraper is designed and built favors it falling more or less straight down rather to one side or the other. The reason being that if it were to topple, as remote a possibility as that is, the building shouldn't be allowed to hit other buildings. Nobody wants a set of dominoes that large.
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Re:oh ok (Score:5, Insightful)
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Re:oh ok (Score:5, Insightful)
Another big reason large buildings tend to fall straight down is that is the direction gravity is pulling them. Anything much bigger than three or four stories is going to come apart very soon after leaving vertical, and the pieces come straight down.
Yeah, you really have to keep in mind just how big these structures are. With the two main towers, there were dozens of floors above the impact point. It's already a phenomenal engineering feat to hold up that amount of weight. Then consider once the frame becomes weakened. Once any point in the structure starts to give, all those floors above start to move, the weak point is going to buckle. Just think about the amount of kinetic energy all that building gains after accelerating only a few feet. There's no way the structure underneath can survive that even if was completely undamaged. Thus why it seemed as though the towers went into free-fall, the amount of downward force being exerted simply tore through everything like it was cray paper, which then itself fell adding to the mass.
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Re:oh ok (Score:5, Insightful)
The difference being that that building was reinforced concrete stack, which is essentially monolithic.
The discussion is about steel skeleton buildings, which have riveted/welded joints that create natural pivots and fulcrums when stresses become off-centered.
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Re:oh ok (Score:5, Insightful)
It looks as though that building fell down because it either became detached from its foundation, or because the foundation wasn't firmly planted in the ground. The above-ground construction of the building doesn't seem to have been the primary cause of the collapse, as the whole thing seemed to remain largely intact before hitting the ground.
I'm not going to say that it's "Apples and Oranges," but that video seems to depict a pretty different scenario.
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Re:oh ok (Score:5, Insightful)
It needn't be as subtle as seeing patterns where there are none, although we know that happens all the time.
In simple terms, things tend to fall down. Surely, if it were easier to get a building to topple over sideways, a team of terrorists isn't going to go through the trouble of averting what would surely be a larger and more spectacular catastrophe.
People whose experience with construction is limited to building models tend to imagine buildings are much lighter relative to the strength of materials in them then they are.
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Re:oh ok (Score:5, Informative)
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Re:oh ok (Score:5, Informative)
Presuming, of course, that such efforts existed.
"Uncontrolled" collapses of very large buildings are exceedingly rare events, so nobody would really know a priori how the WTC collapses "ought" to have looked. After the fact, the way the floors pancaked doesn't seem at all improbable. As the force of the collapse propagates downward, it meets elements designed to spread a fraction of a single floor's weight onto vertical supports. Since the force of the collapse would be orders of magnitude greater than what these elements were designed to support, it seems probable that they would impede the progress of the collapse to about the same degree that a cloud of smoke would impede a lazily swung sledgehammer.
Of course, this is just after the fact rationalization, but the engineering analysis confirms it the intuition that no special measures would need to be taken in order for the collapse to proceed in a way that superficially resembles a controlled implosion.
This conspiracy theory has the usual problems of conspiracy theories, such as providing what mystery writers call "motive, means and opportunity". Motive is a particularly vexing issue, given that seven buildings were destroyed past recovery and numerous other ones damaged, it's hard to connect the end result to the purported motive. Another commonsense question would be whether a government that could not keep Abu Ghraib, Guantanamo, Echelon, or warrantless surveillance under wraps could have engaged in what must have been a substantial engineering effort on three busy Manhattan buildings without anybody noticing.
The real appeal of any conspiracy theory is this:it provides an illusion of control. Limited control, that is certain, but the seat of the pants risk evaluation is actually quite astute: if it were some cabal of government officials, you'd actually be less exposed than if twenty men, each armed with a tool costing $1, could kill nearly three thousand people and bring the country to a virtual standstill for weeks.
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Re:oh ok (Score:5, Funny)
Nobody wants a set of dominoes that large.
Speak for yourself...
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Re:oh ok (Score:5, Funny)
Nobody wants a set of dominoes that large.
Wow, you've never met a human male, have you?
Parent
Re:oh ok (Score:5, Funny)
The way that a skyscraper is designed and built favors it falling more or less straight down rather to one side or the other. The reason being that if it were to topple, as remote a possibility as that is, the building shouldn't be allowed to hit other buildings. Nobody wants a set of dominoes that large.
I can safely say with 100% assurance that that is absolutely not true. I would kill to see a set of dominoes that size.
Parent
Re:So? (Score:5, Insightful)
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Re:Really? (Score:5, Funny)
Let's just get this out of the way first. BULLSHIT!
The rest of the world knows something suspicious went on, but America has their head in the sand.
Not long after this shit, there was a building in Europe, where the fire was so intense, it burned everything off. The steel structure was still standing but oxidizing flame was enough to melt or buckle steel in the trade center? The sheer ignorance of the American populace astounds me.
Interesting. Then I am curious as to what temperature would be required to melt and/or buckle the structure of your aluminum foil hat?
Parent
Re:Really? (Score:5, Insightful)
Let's just get this out of the way first. BULLSHIT!
The rest of the world knows something suspicious went on, but America has their head in the sand. Not long after this shit, there was a building in Europe, where the fire was so intense, it burned everything off. The steel structure was still standing but oxidizing flame was enough to melt or buckle steel in the trade center? The sheer ignorance of the American populace astounds me.
How about if we get this out of the way:
A statement that one building somewhere at sometime didn't collapse under certain conditions is no grounds (in fact it's a logical fallacy) for saying a building couldn't collapse under the same conditions... and worse, it's also no grounds to subsequently stereotype an entire group of people and flame them.
Thank you and have a nice day.
Parent
Re:Really? (Score:5, Informative)
Not long after this shit, there was a building in Europe, where the fire was so intense, it burned everything off. The steel structure was still standing [...]
I'm pretty sure you're talking about the Windsor building in Madrid.
I've got news for you, buddy: It actually works against you.
First, the Windsor building had a concrete core and two concrete technical floors. A very different design from that of the Twin Towers.
Second, the steel portions of the building exposed to the fire did in fact get all melty and collapsey [911myths.com]. The only reason the building is still standing is because of the features I mentioned above.
http://www.911myths.com/html/madrid_windsor_tower.html [911myths.com]
http://www.debunking911.com/madrid.htm [debunking911.com]
Parent
Re:Really? (Score:5, Informative)
Pancaking, a term which you completely misunderstand, is the event which occurs when you cause the upper floors of a building to collapse suddenly. You question how the fire in the upper floors weakened the lower floors. The answer is that it didn't have to. When the upper floors gave way, they impacted the floors directly beneath them. The kinetic energy that is gained by those floors basically free falling 1 story down is immense, and this cause the floor beneath, also weakened by the fire, to collapse, and so on this process went until it reached low enough that the floor beneath the collapsing floors was undamaged by the impact or fire.
The problem though is two-fold: first of all, those collapsing upper floors sent a huge shockwave of compressing air down the elevator shafts and stairwells, blowing out the windows on the floors below and causing some very minor structural damage. No big deal, but it's what makes people think the lower floors were "blown out". The big thing is that by this point, the upper floors have gained such an incredible amount of momentum from their falling, which is only increasing with their mass, that the lower floors have no hope of "catching" them. I say "catching" because they're not supporting them, they have to stop them from a freefall, and stopping an object in motion, especially an object composed of tons of concrete and steel falling directly downward, requires more structural integrity than any skyscraper has.
This is why the Windsor building is a poor example. This event did not occur. It was the WTC's own height working against it, giving the collapsing segments more and more mass until it was enough energy to break through the structurally sound floors.
People who claim there should have been a core, or or more left of it are people who try to compare this to other events, and often lack an understanding of physics and engineering. ALL of the steel in the WTC towers did not have to melt or be weakened. Only a small portion, in a small area, had to be structurally weakened enough to give way. The rest is simply F=ma
Parent
Re:obligatory comment. (Score:5, Funny)
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Re:obligatory comment. (Score:5, Funny)
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Re:"Crackpot Theories" (Score:5, Insightful)
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Re:"Crackpot Theories" (Score:5, Insightful)
How many skyscrapers have people seen collapse which are NOT controlled demolitions?
In other words, how many data points do you have on "What does a skyscraper collapsing on its own look like"?
In other other words, how do you know that "falling straight down" is an artifact of controlled demolition, and not an artifact of being a skyscraper?
Parent
Re:"Crackpot Theories" (Score:5, Insightful)
The claims about it being controlled demolition misses some points that are important. No controlled demolition has ever been done for a building even the size of WTC7, let alone the main towers. The tallest ever was done by CDI in 1998, when the 439-foot-tall JL Hudson Department Store was brought down. The original WTC7 was 610 feet tall, and of course the main towers were more than twice that. Trying to map that out without being fairly obvious would be difficult at best.
It seems to me, in a bit of a thought experiment, that it makes sense that a skyscraper should come straight down, more or less. They are built around structures that are designed to withstand significant loads due to wind, bending slightly but not that much overall. If structural member breaks, even if it breaks outward, there will likely still be some connectivity to the core, preventing it from moving outward. The additional stress added to local joints would cause them to fail, but in a less outward direction, as some of that energy has already been redirected downward. This continues around the building as the collapse continues. Some of the materials in other parts of the building will tend towards their own outward motion, but be pulled back in by the remaining connection to the core, canceling out some of the momentum in the other direction. Ultimately, everything comes straight down.
I think that makes some sense.
Parent
Re:"Crackpot Theories" (Score:5, Insightful)
Both are afected by gravity, which exerts a downward force.
Parent
Re:"Crackpot Theories" (Score:5, Insightful)
Yes, you're right, holocaust deniers, intelligent design proponents, and 9/11 conspiracy theorists all feel like they've been denied the right to debate their theories.
The thing is, they're lying to themselves. They have lots of debates. I've heard 9/11 conspiracy theories deconstructed and made out to be bullshit lots and lots of times. Holocaust deniers do have conventions (like the one in Iran last year). Intelligent design, which should be laughed out of any adult conversation, has managed to actually be taught in schools and considered in courts of law. All of these people already get way, way, way, way, way more attention than their theories deserve.
These people say the opposite of the truth, not only when spouting their absurd theories, but when explaining why other people won't listen to them. "Oh, they're just sheep, led astray by a huge conspiracy." No, actually, you're a petty fool with a reality deficit. We don't ignore you because we are dummies, we ignore you because we have better judgment than you do and can see thru what you say.
Parent
Re:So... Umm... (Score:5, Informative)
About 23,000 gal. of diesel fuel was stored in the bldg, mainly on the bottom floors but some as high as the 7th. "Several months after the WTC 7 collapse, a contractor recovered" the fuel from the tanks and, "unaccounted fuel totaled... somewhere between 0 and 2,000 gallons..." And "The worst-case scenarios associated with fires being fed by ruptured fuel lines-or from fuel stored in day tanks on the lower floors-could not have been sustained long enough, could not have generated sufficient heat to weaken critical interior columns, and/or would have produced large amounts of visible smoke from the lower floors, which were not observed."
http://www.nist.gov/public_affairs/factsheet/wtc_qa_082108.html [nist.gov]
Anyway, steel bends in fires, that's why it has to be insulated and why steel bldg's must have sprinkler systems. I doubt the fire dept. was able to respond effectively in time.
Parent
Who modded this up? (Score:5, Insightful)
This is WTC 7 that we are talking about, not towers 1 or 2. It wasn't struck by a plane and didn't have hundreds of gallons of aviation fuel in it. As colfer pointed out, it had some diesel fuel tanks in the basement, but these were found to have not contributed largely to the fire (which was on the upper stories).
The conclusion of the board is that a normal building/office fire starting by falling debris from WTC 1 is what brought the building down. If we are going to be building dense cities with skyscrapers then it is important that a normal fire merely gut the building, not compromise it's structural support. The building techniques used in WTC 7 were not sufficient, and shouldn't be used in the future.
Parent
Re:So... Umm... (Score:5, Informative)
Yeah, we've been so lucky to find Mohammed Atta's passport in pristine condition several blocks from Ground Zero one day after that hell-like firestorm brought down 1.2 million ton of material.
This [eclipsetours.com]... survived this [eb.com]...
Parent
Re:So... Umm... (Score:5, Informative)
The fire in the North Tower was still burning and spreading when the tower collapsed. While it was obscured somewhat by dust and smoke during the fall, flaming debris did spread out over considerable distances, some of it striking WTC7, breaking through the windows and setting aflame material in the lower floors, which spread rapidly as the collapse of the Twin Towers had done considerable damage to the water systems in the area, and water pressure for the firefighting systems was very low.
The immediate evacuation of WTC7 (among others) as soon as the evacuation of the main towers was ordered saved a great many lives.
Parent
Re:No "crackpot theories" here... (Score:5, Informative)
I saw the video link, it might be helpful to you to be accurate and precise with what the owner said when you report. The owner said the firefighters had come to him and said they couldn't sustain the effort needed to control the fire and that they should pull "it". The "it" referred to the effort to control the fire, not pull the building down. The firefighters were admitting what they were doing was ineffective and they couldn't sustain the effort. They concluded there was nothing they could do so they told the owner they'd pull out the effort spent on the building.
The abutment of that clip with the building collapsing is misleading as is the whole clip. It is just someone's effort for 15 minutes of fame and nimrods like you help him...pathetic...
Gerry
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Re:The Same Old Wrong Conclusions (Score:5, Insightful)
That's why firefighters had no fear whatsoever of going in there.
Citation needed.
I don't need any research to tell me that if you fly a large passenger airplane into a building then something really bad going to happen to it.
As far as WTC7, I've seen a whole neighborhood burned down in less than an hour because of one house catching on fire, I'm strangely led to believe that something on a much larger scale could have similar effects.
Parent
Re:here's some science for you. (Score:5, Insightful)
You may wish to learn a little bit more about gravity here: http://en.wikipedia.org/wiki/Standard_gravity [wikipedia.org] .
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I have worked in wrecking, do you have a clue? (Score:5, Informative)
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Re:truthers == IDers (Score:5, Interesting)
The real cover up is that the buildings weren't code to begin with, or rather David Rockefeller etc bent building codes to get them built.
Indeed. The person involved in 9/11 that I'd prefer most to see behind bars is the one who approved the choice of plaster for walls of the staircases. Whoever he is, he has at least hundreds of lives on his conscience.
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Re:Mission Accomplished (Score:5, Informative)
Fire doesn't melt steel. If you did metallurgy in college, you would know that above a certain temperature the most stable crystalline structure of steel becomes one which is a lot weaker. If you really care, you can google to find phase diagrams of steel like this one [wikimedia.org] that tell you exactly how steel behaves when you heat it up.
If you didn't do metallurgy in college, then you have no idea what you're talking about.
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Re:This is not supposed to be a restricted forum. (Score:5, Informative)
How can anyone on this web site stand there and demand to limit to science as if the fact that the only steel buildings in existence to ever fall from fire all did so on 9/11 (which includes WTC Building 7).
This is absolutely false. There are many examples of other steel buildings that collapsed due to fire before 9/11. One example off the top of my head would be the Sight and Sound Theater fire of 1997. http://www.firefightersonline.com/opsandtactics/tr-097/ [firefightersonline.com] Just google around for a few minutes if you want many more examples.
The way 9/11 conspiracy theorists mindlessly repeat these lies (like the lie that no other steel buildings have collapsed due to fire) without bothering to spend even five minutes googling around with terms like "steel building fire collapse" is a testimony to their extreme gullibility and intellectual laziness. It's not different than the oft-repeated claim that the fire wasn't hot enough to melt steel, which ignores the fact that steel loses much of its strength well before it actually melts.
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