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Total Building Collapse from a Single Column Failure

ozeco41 said:
1) Yes - including me.
2) Yes - even though it doesn't need fixing when one side has only very weak moles.
3) Yes - it's the sad reality of 9/11 discussion - all the serious stuff dealt with years back.
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What is really comical is when you look at troofer forums.

1)We are "scared" of them
2)It is only a matter of time before the majority of people see the light
3)The JREF forum is in shambles.

:rolleyes:
 
Animal said:
What is really comical is when you look at troofer forums.

1)We are "scared" of them...
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Some are "scared" of me ;)
Animal said:
2)It is only a matter of time before the majority of people see the light...
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Most of us already have. And that includes most of the former "genuine truthers". Some of us didn't need to walk the Damascus Road - we were never in darkness. A few did. Most former truthers surely have.
Animal said:
3)The JREF forum is in shambles.
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Which usually means "I dare not go there - the arguments are too good for me."
 
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(Snipped for brevity)
ozeco41 said:
a) multiple hints that they - everyone - both sides - should read what NIST actually said;
b) multiple hints from debunkers as to the true situation; AND
c) numerous counter claims from folks claiming to be reading NIST - but obviously either reading the wrong bits, not understanding or simply being untruthful.
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What's annoyed me more than these three points is that for as much time as could be spent actually proving the alternative "theory" all I get is a claim that I'm sort kind of apologist because I demand proof of a "CD" that thus far has not existed, except when throwing out all sense of design intent and critical thinking.

They can point out errors in the NIST report, sure. And if some prove to be legit then congrats, they should be able to explain them. But the only interest I'd take in those errors is for life safety considerations; that's what building code changes address. That's where the claims about these details would provide the most concern for me; the question of are the known code revisions justified? So NIST could be wrong on some things, and it's criticized under those sorts of merits which I could understand, but none of those legit critiques leads to "CD". And so far, this thermal expansion nit picking might have a purpose in determining code issues if any of it proves ultimately legit, but even so... the average CT'er would be disappointed to be reminded that such issues would be an issue of code and egress, not that the buildings were rigged by phantom ninjas.
 
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Tony Szamboti said:
The 53 foot long beams to the east of girder A2001 would buckle at approximately 8,000 lbs of axial force when they were at 600 degrees C. The six 7/8" diameter ASTM A325 bolts in their connection to the girder would require about 18,000 lbs. each to shear at 600 degrees C. That is 108,000 lbs. to break the bolts at 600 degrees C and 8,000 lbs. to buckle the beam.

However, since there were no shear studs on girder A2001 neither failure mode would have occurred since their was no reaction force applied to the expanding beam.

I have explained this several times on this forum.
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That's not math, that's throwing out numbers and saying stuff.
 
It's also TS equating 'no shear studs' with zero reaction force, which is laughable. This desk isn't attached to the floor but if I tried to pull it there would be one hell of a reaction force. It's called friction.
 
Grizzly Bear said:
(Snipped for brevity)...
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By my standards of verbosity err ... "full explanation"...it was already brief. :o

:D

Grizzly Bear said:
What's annoyed me more than these three points is that for as much time as could be spent actually proving the alternative "theory" all I ....(Snipped for brevity :boxedin: )....would be an issue of code and egress, not that the buildings were rigged by phantom ninjas.
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As usual we are in broad agreement. The main point I was making being that even when we spoon feed the answer it gets ignored - and I am convinced it is simply not understood. The engineering must be too complex for some - even when reduced to the bare essentials viz:
1) It's their burden of proof;
2) They have not considered all the factors; AND
3) The "system boundary" of their analysis is wrong.
 
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GlennB said:
It's also TS equating 'no shear studs' with zero reaction force, which is laughable. This desk isn't attached to the floor but if I tried to pull it there would be one hell of a reaction force. It's called friction.
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The girder had a 131 kip floor load and the coefficient of friction for steel on steel is about 0.2. So the total reaction force would have been about 26,000 lbs.

That would be about 5,200 lbs. per beam and doesn't even come up to the 8,000 lb. load required to buckle a slender beam at 600 degrees C, let alone the 108,000 lb. load required to break the connection bolts of each beam.

Anyone trying to say the beams buckled and/or the bolts broke doesn't have any idea and shouldn't even be commenting about it.
 
Tony Szamboti said:
The girder had a 131 kip floor load and the coefficient of friction for steel on steel is about 0.2. So the total reaction force would have been about 26,000 lbs.

That would be about 5,200 lbs. per beam and doesn't even come up to the 8,000 lb. load required to buckle a slender beam at 600 degrees C, let alone the 108,000 lb. load required to break the connection bolts of each beam.

Anyone trying to say the beams buckled and/or the bolts broke doesn't have any idea and shouldn't even be commenting about it.
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Sounds fair for beams in pristine condition.

WTC7, not so much.
 
LSSBB said:
That's not math, that's throwing out numbers and saying stuff.
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The W24 x 55 beams were 53 foot (636 inch) long and that section has a moment of inertia of 29.1 in.^4 in its weak axis. Per the AISC, the modulus of elasticity of structural steel at 600 degrees C is 11,310,000 psi.

The equation for buckling force is

(Pi^2 x modulus of elasticity x moment of inertia) / unsupported length ^2

So, to buckle those beams with their shear studs broken and their temperature at 600 degrees C, the force would be

(3.14^2 x 11,310,000 x 29.1) / (636^2) = 8,030 lbs.

ASTM A325 bolts between 1/2" and 1" have a guaranteed minimum yield strength of 92,000 psi. See http://en.wikipedia.org/wiki/ASTM_A325

In a forensic analysis the rule is to multiply the guaranteed minimum by 1.1 so the yield strength would be 101,200 psi.

At 600 degrees C steel has lost about half its strength so that puts the yield strength at 50,600 psi. In shear the yield strength is 57.7% of tension and compression. So that puts the bolt shear yield strength at about 29,196 psi at a 600 degree C temperature.

The bolts were 7/8" diameter and had a shear area of 0.601 in.^2 so to shear each bolt would require

29,196 psi x 0.601 in^2 = 17,546 lbs.

To shear the six bolts at each connection would require 105,276 lbs.
 
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DGM said:
Wouldn't that be just the calculations with the beam in isolation, not existing condition (like in the model)?
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No, it would be what would occur if the beams had broken their shear studs just like NIST says in their model.
 
DGM said:
So, the beams temp would be the same through out all of it's dimensions (consistent)?
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NIST says they put the beams at one temperature and did not use a gradient in the structural analysis.

Additionally, the values I showed for buckling the beams and shearing the bolts are the minimums and they significantly exceed any reaction force the girder could have applied, so the beams would not buckle and their connection bolts to the girder would not break. The comments by some here of that type of thing happening is simply not supportable.
 
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DGM said:
Sort of like your comments on controlled demolition? ;)

I really like the penthouse as a separate event. That's some serious reaching. :rolleyes:
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What you want to think doesn't matter. It is only what is observed and the reality of what was possible that counts.

There is no chance the entire east side interior could have come down before the exterior, the way the NIST report wants to say, without east side exterior deformation and dust emanating from the windows. Neither are observed until the entire exterior comes down.
 
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Tony Szamboti said:
What you want to think doesn't matter. It is only what is observed and the reality of what was possible that counts.

There is no chance the entire east side interior could have come down before the exterior, the way the NIST report wants to say, without exterior deformation and dust emanating from the windows. Neither are observed until the exterior comes down.
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Video shows your "penthouse separate theory" wrong. That's been pointed out many times. The deformation can be seen, you just claim it's not enough and it no longer matters.
 
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