Question About the WTC Core Collapse

[scooby]

Except that by changing the geometry of the model you've changed the structural response.

But isn't that standard practice in scientific America these days?
Didn't NIST change the geometry of the model in order to induce a failure?
I heard they couldn't get it to fail using the real values so they changed them, oh like for instance, metal trusses sagging 3 or 4 inches in a fire - let's make that 42 inches. That kind of thing.

 

[332nd]

But isn't that standard practice in scientific America these days?
Didn't NIST change the geometry of the model in order to induce a failure?
I heard they couldn't get it to fail using the real values so they changed them, oh like for instance, metal trusses sagging 3 or 4 inches in a fire - let's make that 42 inches. That kind of thing.

I heard my Panthers "won" Super Bowl XLI from my roomie for a year. (He bet they would cover the spread)

Where did you hear they changed the values?

 

[uk_dave]

But isn't that standard practice in scientific America these days?
Didn't NIST change the geometry of the model in order to induce a failure?
I heard they couldn't get it to fail using the real values so they changed them, oh like for instance, metal trusses sagging 3 or 4 inches in a fire - let's make that 42 inches. That kind of thing.

Check the photographs of the side of the tower before collapse and you'll see the floor trusses are sagging by alot more than 3 inches.

Can you prove NIST was wrong in it's figures?

Oh and my earlier point, which was at odds with your preconceived ideas and therefore subject to your lame attempt at scorn, still stands.

The core columns failed at the connections due to the stresses imposed upon them by:

• Failure of the trusses (i.e being pulled by the sagging trusses)
• Fire
• The collapse of thousands of tons of debris

In just the same way that the core was :

• Not Concrete
• Not built to be freestanding from foundation to roof while the rest of the construction was built around it (important one as this appears to be a cornerstone of the 'truther' fantasy regarding the towers)
• Not made of continuous lengths of steel
• Not crossbraced at the corners (remember the crane towers?)

..the 'truthers' have not the faintest idea about construction of steel framed multistorey structures, the effect of fire on steel or the effect of gravity on an unstable structure.

 

[Totovader]

But isn't that standard practice in scientific America these days?
Didn't NIST change the geometry of the model in order to induce a failure?
I heard they couldn't get it to fail using the real values so they changed them, oh like for instance, metal trusses sagging 3 or 4 inches in a fire - let's make that 42 inches. That kind of thing.

"That kind of thing"? That seems to be a rather obvious way of injecting a completely ridiculous lie so that you don't actually have to do any research.

Change the geometry of the model?

Come on, be honest- you have a chicken wire model, don't you? You're just looking for an excuse to whip it out... go on, post pictures of your chicken wire model.

 

[David Wong]

I heard they couldn't get it to fail using the real values so they changed them...

I heard George W. Bush is bigfoot in disguise.

The moment we can convict people of complicity in mass murder by unsubstantiated "I heard" statements, is the moment we can give up any idea of justice or even kind of skeptical inquiry.

Evidence, young man. Bring evidence.

 

[gumboot]

I heard they couldn't get it to fail using the real values so they changed them, oh like for instance, metal trusses sagging 3 or 4 inches in a fire - let's make that 42 inches. That kind of thing.

Photographic evidence reveals some of the floors in the impact zone sagged a distance in excess of a floor height.

In other words, floor 98 was sagging below what used to be the floor level fo 97.

Doing a fast and dirty calculation, that's about 4m, or almost 160 inches.

By the way... the floor trusses didn't fail, incase you failed to pick that piece of info up when you read all 10,000 pages of the NIST report. It's quite important, so I figured you would have registered that little detail at least.

-Gumboot

 

[Andúril]

Hello,

This is my first post & thread so please take it easy on me! For the past year I have been working for the CIA, FBI, FEMA, NIST, and the Bush administration. The location of my work is not classified as I am well known at the ATS site. To them, I am the beast... the shill..the troll...whatever the favorite term for the day is to label someone with common sense.

My problem, i am not at all good with physics and engineering. I had a question asked of me in regards to the last part of the core than remained standing for a short time after the collapse. I was asked WHY it fell straight down after the global collapse had occurred and why it didn't fall "over". I really don't have an educated guess as to how or why.

Not sure if this has ever been brought up in here. I do come in here often to read the threads, but don't recall ever seeing any such question.

Any help you could give me would be much appreciated.

Thanks

There really is nothing special. When a 300-meter tall piece of a column is angled for just a few degrees, its own weight causes an enormous twist moment near its "root" and it simply snaps from some joint or other weak spot. Then the rest of the column comes down in freefall, with gravity giving it a good amount of kinetic energy. When the lower end of the column then hits the ground, this force breaks or bends it practically immediately and so on. In order for it to fall over as a single piece it should either be very strong and stiff or rotate very fast to eliminate the effects of gravity. Build a tall, thin column of, for example, 1x2 Lego blocks and angle it a bit - the same principles apply in both cases. Not entirely, though, because it's impossible to accurately model anything big in a small scale, because things like g and the properties of materials are not scaled down in the same ratio. The bigger the model is, the better.

 

[westprog]

Scale Modelling doesn't work

One of the commonest errors of the CT's is the assumption that a scale model will demonstrate the same behaviour as the full size thing. It's been demonstrated that this is not the case, repeatedly. The most obvious reason is that if scale models exhibited the same behaviour as the full size building, then architecture would be a very easy discipline. Rather than complex calculations of weight and force, they could just throw a model together and see if it stays up.

 

[gumboot]

One of the commonest errors of the CT's is the assumption that a scale model will demonstrate the same behaviour as the full size thing. It's been demonstrated that this is not the case, repeatedly. The most obvious reason is that if scale models exhibited the same behaviour as the full size building, then architecture would be a very easy discipline. Rather than complex calculations of weight and force, they could just throw a model together and see if it stays up.

It depends on what it's for. Scale models, for example, are perfectly fine for doing wind tests. Using them to test structural integrity is absurd. Using them to study complex catastrophic events is simply insane. Building a scale model of the WTC out of [insert CTer building material here] in order to understand 9/11 is about as useful as using your bathtub to replicate Hurricane Katrina.

-Gumboot

 

[mailman]

Yet you still don't know what 'leaning' means.
How long will they have to keep it there, for you to work it out?

So lemme see if I have got this right.

You are using something as an example of what you believe should happen but your example HASNT actually fallen over yet!

BWAAAAAHHAHAHAHAAAAAAAA

Mailman

 

[scooby]

I heard my Panthers "won" Super Bowl XLI from my roomie for a year. (He bet they would cover the spread)

Where did you hear they changed the values?

Steve Jones mentioned it in this video I came across recently ...

9/11 Truth: NIST Report Debunked
http://www.dailymotion.com/video/x1cvkz_911-truth-nist-report-debunked

 

[Zep]

Just one word: HUSH-A-BOOM!

 

[kookbreaker]

Steve Jones mentioned it in this video I came across recently ...

9/11 Truth: NIST Report Debunked
http://www.dailymotion.com/video/x1cvkz_911-truth-nist-report-debunked

So you pretty much swallow any lie that the CT crowd sends down the pipe?

The 'NIST manipulated the model' lie has been around for a while. It is told by fools who do not know how computer modeling works, or outright liars who want their fantasy to be true by any means.

Either way, you are wrong.

 

[WildCat]

Steve Jones mentioned it in this video I came across recently ...

Did it ever occur to you to check the NIST report for yourself to see if Jones is telling the truth? If you did, you'd discover that Jones is a liar, a charlatan, and a profiteer taking advantage of the feeble-minded.

 

[Myriad]

Except that by changing the geometry of the model you've changed the structural response - the slenderness ratio, for example, is dependent on the relationship between the length of a column and the radius of gyration (which is dependent on cross-section). You could use the same geometry, but with a different material - except that doing so would present its own set of problems. You haven't mentioned anything about heat transfer either, which can get really nasty with that fourth power in the radiative component.

Granted. And I understand and agree with the point you were leading toward (directed at Scooby), to let experts do the analysis they (and they alone) are trained and qualified to do.

However, you've misconstrued the intended purpose of the model I described. It is not intended to perform dynamical analysis of precise failure scenarios, nor even to be actually built at all. It is to give the audience a more accurate (not completely accurate, but more accurate) mental model of what a scale model of a building would have to be like to truly reflect a real building's ratio of structural strength to weight load. Instead of chicken wire or erector set struts or even paper, such a model would have to be built of gossamer-like filaments of steel and loaded with additional weight as I described. Alternatively, as you suggested, it might be built of a rigid material much weaker than steel (strands of dry angel hair pasta might be close, within an order of mangitude or two, but would still have to be loaded with extra weight).

As a thought experiment, such a model is far more interesting and gives a far better intuitive sense of approximately "what would happen" under various conditions than Scooby's steel-rod-in-a-pipe. For instance, you couldn't pick it up with your hands (your fingers would just tear through it) just as a real building cannot be lifted up without evenly lifting every vertical structural member at the base. You couldn't tilt it or even knock it over; as soon as that 14 pounds of weight were no longer centered over the delicate support members, it would buckle at the base and collapse downward.

To paraphrase a well-known Asimov passage: Scooby's conceptual model, a meter-high steel-rod-in-a-pipe, is wrong. My conceptual model, of 14 grams of steel filaments forming a meter-tall framework supporting 6 kilograms of load, is also wrong. But if you think my model is just as wrong as Scooby's model, you're wronger than both of us put together!

Respectfully,
Myriad

 

[Cl1mh4224rd]

Of course for the remaining core to all drop straight down at the same time without toppling, would require simultaneous removal of all remaining support at the same time.

Hmm...

lol... These really are some amazing demolition charges you people dream up.

 

[AZCat]

Granted. And I understand and agree with the point you were leading toward (directed at Scooby), to let experts do the analysis they (and they alone) are trained and qualified to do.

However, you've misconstrued the intended purpose of the model I described. It is not intended...

<words, words, words> (again quite well-written)

...
To paraphrase a well-known Asimov passage: Scooby's conceptual model, a meter-high steel-rod-in-a-pipe, is wrong. My conceptual model, of 14 grams of steel filaments forming a meter-tall framework supporting 6 kilograms of load, is also wrong. But if you think my model is just as wrong as Scooby's model, you're wronger than both of us put together!

Respectfully,
Myriad

I understand that you were illustrating a certain point, without planning on building the actual model. But since I have seen several "truthers" use their chicken-wire models for thermal tests, I thought it would be important to point out that there are more problems than the ones you discuss.

Any model, as long as the limitations are understood, isn't "wrong". Your model is only intended to test certain things and is capable of properly doing so (provided it is constructed as specified). Using your model for testing other phenomena (such as heat transfer or buckling) is outside the scope of the model and will give faulty responses, but again - that doesn't invalidate its responses for the phenomena it was intended to study.

Please don't take my "riffing" off of your post as criticism - you explicated this far better than I could have.

 

[scooby]

Did it ever occur to you to check the NIST report for yourself to see if Jones is telling the truth? If you did, you'd discover that Jones is a liar, a charlatan, and a profiteer taking advantage of the feeble-minded.

Never, it's conclusion tells you all you need to know about its content.
I must say it was news to me that Steve Jones lied about this though - are you sure?

 

[The Almond]

Never, it's conclusion tells you all you need to know about its content.

Would you care to tell me what NIST's conclusion was?

I must say it was news to me that Steve Jones lied about this though - are you sure?

Jones uses a lot of out-of-context quotations and misrepresentations of the actual report. It depends on your definition of a lie, but I do belive he deliberately trims and edits his quotes to change the meaning of them. That's dishonest, at least.

 

[twinstead]

Personally, I am totally not qualified to judge the validity of Jone's statements. All I have is what his peers and members of the structural engineering community have to say about them. To be kind, they are singularly unimpressed.

Franky, what scooby and others like him has to say about them makes no impact in my decision on who to believe at all.

I suppose the mainstream could be totally wrong about him. I'm not going to hold my breath waiting for somebody with relevant qualifications to come to his aid however.