Moderated Steel structures cannot globally collapse due to gravity alone

Christopher7 said:
You have an "unanswered question problem" too.

NIST did not explain how the Trade Towers collapsed completely.

Bazant did not explain how the south Tower collapsed.
[even if you believe he explained the collapse of the North Tower]
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Chris (and everybody) this is a fantastically useful photo of ground zero and the whole area really. It's zoomable and i believe it was taken 12-09-2001. Teddy can confirm that.. Maybe you lready have it ?
http://www.engr.psu.edu/ae/WTC/wtc-photo.jpg Huge photo (slow loading)
 
BenBurch said:
Bazant starts out; "This paper presents a simplified approximate analysis..."

Why are you treating it as detailed in the first place?
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Some people were touting it as an explanation for the collapse of the Trade towers.
It is not.
 
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Christopher7 said:
Yes, I know.

He allowed 20% for ejected material.

He said compressed air ejected " a mass of dust and larger fragments"

He did not mention "bursting" or explain what ejected the 4 ton framework sections up to 500 feet.

He only said that large steel pieces were ejected at velocity z˙.

Source?

This is not a "minute" point.
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Chris, that's a ridiculous response. My whole point was to show you were substantially wrong in saying that Bazant and his colleagues did not account for shed mass. You singled out one specific failure mode - bursting - and tried to refute Bazant et. al.'s work by saying he didn't address that. I was pointing out that that was a disingenuous argument, that Bazant of course did not discuss specific failure modes and incidents, he and his colleagues only demonstrated that there was enough energy available to drive any failures that may have happened. Whether those failures resulted in columns embedding themselves in buildings across the street or not is not part of his argument, and neither is whether they "burst", bent, spun, hinged, or whatever. There was enough energy there for those failures to happen period, and that's the point. Arguing whether a failure mode was a "bursting" or not, and where a piece ends up after detaching is irrelevant to Bazant et. al.'s model because it does not bring into question whether there was enough energy present for the failures to happen in the first place. How they manifested and where detached pieces ended up was beyond their scope.

If you think that specific manifestations of failure and details of where pieces ultimately ended up is significant, then explain why. All you do is say that failure mode wasn't addressed, therefore Bazant is wrong/piece ended up across the street, therefore Bazant is wrong. No, no, no... those points do not contradict B&Z or BLBG. They merely demonstrate the chaotic nature of the collapse, not that the energy wasn't available. Explain why you think those points contradict B&Z and BLBG. Don't just pick at points; that gets nowhere.
 
ElMondoHummus said:
Bazant of course did not discuss specific failure modes and incidents, he and his colleagues only demonstrated that there was enough energy available to drive any failures that may have happened.
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Correct.

He did not describe or confirm the cause of the collapses.
 
Heiwa,

Heiwa said:
Me, ignore gravity? I just maintan You see, you cannot destroy a structure by dropping a piece of it on the whole. Noone seems to be able to debunk it!
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You are confusing your refusal to understand for others' inability to debunk.

Heiwa said:
My paper won me the A&E911 truth Petitioner of the Month (of February 2009) appointment to Gravy's (Mark Roberts) big disappointment. He started another thread about it spilling his malignant venom there.
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It's not quite "Damned by Faint Praise".

Perhaps "Damned by Foolish Praise".

Heiwa said:
To Bill Smith! Pictures of really buckled/kneeled columns are in my paper. None found in the WTC rubble, of course.
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Are you sure that you want to make this statement?
http://911research.wtc7.net/mirrors/guardian2/wtc/fig-4-17.jpg

BTW, the term is

Heiwa said:
An assembly of kneeled columns cannot produce free fall of any load above and cannot therefore not initiate any crush down by any load above.
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Of course they can.

Parts fail due to local stress levels. Nothing else. Although there are several different kinds of stress. e.g., tensile & compressive, bending, shear, fatigue, etc.

Stress depends on loads and geometries. Changes in either can, and generally will, cause changes in stress levels.

In a lattice structure like the towers, the process of one or more columns "kneeling" will, by definition, change some amount of load geometries on some collection of columns.

In a similar fashion, the process of some columns "kneeling" will very likely change the load levels in some collection of columns.

Both of these causes will result in changed stress levels in some group of columns. Almost always, the columns that If either of these changes produce stress levels that exceed stress limits in that or other structural members, then those members will fail.

What happens subsequent to those failures depends entirely on the nature of the entire structure. Specifically the redundancy and susceptibility to single point failure.

In the case of the WTC Towers & WTC7, a couple hundred single point failures did NOT progress to total collapse.

And then one final single point failure DID lead to total collapse. At NEAR free fall accelerations. In all three cases, from "crush down" from loads above.

tk
 
BenBurch said:
Why are you taking Bazant, an paper that was a practically a first attempt to explain the collapse utterly superseded by among other things the NIST report, as Gospel on ANYTHING?

I mean, that would be like me using Lord Kelvin's computed age of the Earth in a geology argument.
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so he can say;

"Oh I so Pwned him!" of course.

TAM:)
 
bill smith said:
....terminal velocity at an oblique angle defying gravity in a straight line. Looks like it was blown out there.
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Why do you claim this? Can you show the forces (other than gravity) that you propose would do this. If not your just blowing smoke (I suspect this is the case judging from his other responses).
 
bill smith said:
As regards the snapping of the bolts- the falling mass on the inside would have bent the bottom-attached columns outwards before the bolts snapped.and he rubble inside would have extruded out on top of them in one motion. The tendency is all wownwards and not outwards.
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I can't quite make sense of this statement? I think you are speaking of the spandrel bolts that attached the floors to the inner and outer columns? The mass accumulated between the core and outer shell would have sheared the bolts. No appreciable bowing of the exterior in any direction.
 
I see Mr Smith has resorted to patting Chris7 on the back and given up on defending his own position. (why do I keep hearing "oh no Will Robertson)

(I know that was Zachary Smith, Showing my age again.)
 
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bill smith said:
Hi Gravy- there are so many areas of 9/11 that do not add up in my opinion. With three thousand dead it needs to be cleared up. The 9/11 Commission report was entirely unsatisfactory and there was- and is no will for an independent enquiry.
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In YOUR opinion. Right! Got it!

To me we only have to establish beyond doubt that the gvernment story is false in many serious respects. We don't have to prove how exactly how it was done. An independent enquiry will ferret that out quickly enough but we will need to force one somehow. I have theories about many of the events which we may get into at some point.
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You ARE aware that we are living in 2009, are you?
 
Christopher7 said:
Correct.

He did not describe or confirm the cause of the collapses.
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(*facepalm*)

3bodyproblem said:
He didn't describe or confirm it was a sunny day either.

I hope your not suggesting he didn't answer "Why?" when he was asked "How?"
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What he said. B&Z made the argument that energy was sufficient, and BLBG refined that analysis. That was the whole, and only point of their work.
 
Christopher7 said:
You are ignoring the point which is:
Bazant does NOT explain what ejected the large steel pieces or how much energy it took.
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I have already given you an answer for both, but your second point is marginally different than the one I originally answered.

The question being "Did BLBG specify how much energy ejection of steel sections took?"

The answer is yes. What you should have noticed, immediately under the formula I reproduced for you in the BLBG paper is this section:
BLBG said:
The computation results shown in figures have been run for κe = 0.2; however, a broad range of κe has been considered in computations, as discussed later.
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I now quote from that further discussion:

BLBG said:
Parametric studies show that, for κe ∈ [0.1, 0.8], the collapse duration varies about 0.31 s, which still matches the video and seismic records reasonably well.
...
If κout is increased from 0.05 to 0.5, the crush-down collapse duration is longer, but not by more than 0.45 s, which still matches the seismic record well enough. For the South Tower, the effect of stage (b) mildly prevails over a considerably long period while effects of stages (a) and (c) are weak. The net result is to lengthen the crush-down duration, but only a little; if κout is varied from 0.05 to 0.5, the crush-down duration increases by only 0.14 s
...
Some lay critics claim that κout should be about 95%, in the (mistaken) belief that this would give a faster collapse and thus vindicate their allegation of free fall. However, such κout value would actually extend the duration of collapse of North Tower by about 2.11 s (and 1.50 s for κout = 90%) because the effect of stage (c) would become dominant.
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I don't really feel I should have to quote much more to explain this. This paper clearly identifies a range of values, has conducted studies to determine realistic values, and provided bounds for the values returned.

What more do you want?
 
Bell said:
In YOUR opinion. Right! Got it!



You ARE aware that we are living in 2009, are you?
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Yes. only my opinion but a reasonably informed one I hope. 2009 or 2019 makes no defference. This will never be over until it's sorted out. Two or three years from now all the world will know hat 9/11 was an inside job. If America is sticking to the Bin Laden-and-the-19-Muslims story it will make for good satire TV worldwide.
 
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