jaydeehess
Penultimate Amazing
Lurking I guess. Difficult to ask any question if one stays in the shadows.
Even more difficult for one to ask one's questions if one does not even exist.
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Lurking I guess. Difficult to ask any question if one stays in the shadows.
Even more difficult for one to ask one's questions if one does not even exist.
BasqueArch
Graduate Poster
- Joined
- Jan 11, 2009
- Messages
- 1,871
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[FONT="]Here is a short version of the most detailed explanation of how NIST described the failure of girder C79-44 for a one floor model in their report, NCSTAR 1-9, section 8.8, their pp. 349-354.[/FONT]
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[FONT="]The expanding beams pushed the C79-44 girder to the west. The expanding girder jammed at C79 and C44. The beams continued to expand and were axially compressed by the resisting girder, buckling the beams. The sagging beams rotated the heated, buckled girder to the east. Figures 8-26, 8-27. At a certain rotated critical angle of the top flange, (pp.487-488) the girder failed to carry its load and fell.[/FONT]
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[FONT="] “[/FONT][FONT="]Axial compression then increased in the floor beams, and at a beam temperature of 436 °C, the northmost beam began to buckle laterally. Buckling of other floor beams followed as shown in Figure 8–27 (a), leading to collapse of the floor system, and rocking of the girder off its seat at Column 79 as shown in Figure 8–27 (b)” (p. 353)[/FONT]
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[FONT="]It should also be noted that whereas the attention has been focused on the seat at C79, this unrestrained girder condition at this seat was of an area of a few square inches whereas the twisting forces on the girder occurred unimpeded over the rest of the ~44 foot girder, failing it as NIST noted in their lateral- torsional buckling analysis and figures.[/FONT]
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[FONT="]The expanding beams twisted, pushed, rocked the girder off its seat. The girder walked off the seat. The girder and WTC7 failed due to fire, not explosives.[/FONT]
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[FONT="]Here is a short version of the most detailed explanation of how NIST described the failure of girder C79-44 for a one floor model in their report, NCSTAR 1-9, section 8.8, their pp. 349-354.[/FONT]
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[FONT="]The expanding beams pushed the C79-44 girder to the west. The expanding girder jammed at C79 and C44. The beams continued to expand and were axially compressed by the resisting girder, buckling the beams. The sagging beams rotated the heated, buckled girder to the east. Figures 8-26, 8-27. At a certain rotated critical angle of the top flange, (pp.487-488) the girder failed to carry its load and fell.[/FONT]
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[FONT="] “[/FONT][FONT="]Axial compression then increased in the floor beams, and at a beam temperature of 436 °C, the northmost beam began to buckle laterally. Buckling of other floor beams followed as shown in Figure 8–27 (a), leading to collapse of the floor system, and rocking of the girder off its seat at Column 79 as shown in Figure 8–27 (b)” (p. 353)[/FONT]
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[FONT="]It should also be noted that whereas the attention has been focused on the seat at C79, this unrestrained girder condition at this seat was of an area of a few square inches whereas the twisting forces on the girder occurred unimpeded over the rest of the ~44 foot girder, failing it as NIST noted in their lateral- torsional buckling analysis and figures.[/FONT]
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[FONT="]The expanding beams twisted, pushed, rocked the girder off its seat. The girder walked off the seat. The girder and WTC7 failed due to fire, not explosives.[/FONT]
Animal
Master Poster
Wow......continue to show your ignorance of building structures.
Lateral movement of the column and lateral instability from column slenderness are two very different issues.
Time to run back to your team of "experts" for some more schooling, lest you make a bigger fool of yourself
This column has been "dsiplaced" in multiple directions yet it is still stable.
Column 79 could easily been deformed in a similar fashion yet maintain it structural stability as long as Euler still worked for it. Once the girder walked off and started the floor failures.......the column failed.
Once again.....a troofer fail.
My understanding is he might be referring to this post:Wrong.
As always, you are wrong.
Someone proposed a debate between myself and Jay Howard about the Harrit-paper. Jay said he'd be all for it. So I opened a thread for that:
http://www.internationalskeptics.com/forums/showthread.php?t=289588
So far, Jay hasn't reported in.
By the way: You'd be one of the trolls
And possibly mixing it up with the other thread.
Animal
Master Poster
Troofers hang their religious beliefs on the 6.25 inches and that the longest beam could not expand that far to push the girder off......part of their "pristine building" myopic view. As you illustrated, there is far more going on around that column than a simple one beam expansion. The NIST did not even bother to consider seat failure.......just as likely a portion of what happened as was the displacement of the column to the east, beam and girder twisting as you noted, other beams expanding a shorter distance and leverage causing a greater movement, etc, etc.
It does all boil down to The girder and WTC7 failed due to fire, not explosives.
chrismohr
Master Poster
- Joined
- Mar 14, 2011
- Messages
- 2,080
Except for receiving some unsolicited emails from Ziggi, I am not a party to what he is doing here. However, I am happy to see a substantive debate going on and am learning from it.
This is from chapter 8 which is a set up scenario for the failure of the sheer studs, not the final walk off theory, which is summed up in chapter 11, and is completely different. There are many condlicting stories in the report, to be fair, which is why it has confused so many people for such a long time. IF you want to learn about the final story, the walk off event, stick to chapter 11.
Of course you are a part of this Chris, I made sure to inform both you and Rick together to make sure you could not ignore this.
Is it surprising for you to discover that NIST never actually scientifically supports the plausibility of its given 6.25 inch expansion number, and that we have to take it on faith?
We did this supposedly hard core forum of skeptics not say anything?
They set up a simulation, ran it and reported on its results. What is unscientific about it? I've seen a number of papers doing the same.
For the sake of example, let me cite this paper I recently wrote about in my blog:
- Richard Oberdorf, Allison Ferguson, Jesper L. Jacobsen and Jané Kondev: Secondary Structures in Long Compact Polymers (2008) (preprint).
Same thing with NIST. They explain the methods and report on the results of the simulation. Like it or not, that's standard scientific practice.
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WilliamSeger
Philosopher
- Joined
- Nov 28, 2006
- Messages
- 5,092
This is a silly game. Conspiracy theorists will always reject the NIST hypothesis because it isn't "proved," and it never will be since there weren't any cameras inside the building. The game is to avoid the question: What hypothesis is more plausible, and why is it more plausible? There could be many, but I don't see "magical silent, fireproof explosives" on the list.'
Two possibilities are admitted to be exact, and more importantly, two possibilities for beams and girders, meaning JayUtah´s authoritarian declaration about this second possibility only applying to beams was wrong:
"Therefore, when the web was no longer supported by the bearing seat, the beam was assumed to have lost support, as the flexural stiffness of the bottom flange was assumed to be insufficient for transferring the gravity loads."
Confirming that this option is indeed what NIST´s thermal expansion story is about is easy. Gerry and friends already confirmed that in their discussion with NIST about the stiffeners, and NIST clearly says so itself, page 525:
"A girder was considered to have lost vertical support when its web was no longer supported by the bearing seat. The bearing seat at Column 79 was 11 in. (revised to 12) wide. Thus, when the girder end at Column 79 had been pushed laterally at least 5.5 in (revised to 6.25), it was no longer supported by the bearing seat."
So, again, NIST´s walk off story is that once the girder was somehow displaced 6.25 inches, it was resting on the flange only, which was not stiff/strong enough and folded.
Dear pgimeno, you refuse to get into the numbers for possible displacement and expansion, yet you declare this is about an inch. You won´t know if this is about 1, 3, or 6 inches until you get into the numbers. And this is not just about NIST´s scenario being impossible, this is also about the failure to meet the most basic requirement of science, to show data in support of the conclusion.
And let me point out another little thing, again quoting the same thing from NIST:
"Therefore, when the web was no longer supported by the bearing seat, the beam was assumed to have lost support, as the flexural stiffness of the bottom flange was assumed to be insufficient for transferring the gravity loads."
So it seems that not only is the 6.25 inch displacment just given on faith, but so is the conclusion that the flange would not be strong enough. Are we supposed to take everything on faith because 9/11 is touchy subject?
MileHighMadness
Muse
Typical truther B.S., debating small unimportant details that have little to do with the global collapse.
The truther movement will never die, but it is slowly fading away. Zero evidence, pushing an insane impossible theory. What a waste of one's life.
The truther movement will never die, but it is slowly fading away. Zero evidence, pushing an insane impossible theory. What a waste of one's life.
Animal
Master Poster
It does not matter if it happened or not, and the funny part is 911 truth has no skill to prove otherwise. After 13 years, 911 truth jump on the NIST bashing, and have no clue NIST is not needed to understand WTC 7 failure in fire. Add thermite and explosives and we have conspiracy theories based on ignorance. After 13 years it is pathetic the best 911 truth can do is BS about a building not a target of 19 terrorists.
Why can't you refute the 6.25 expansion? Then you ignore that is not the only item affected by fire in WTC 7.
What do you say about the OP? Deets ignores 6 or more seconds of WTC 7 interior collapsing, which is why the WTC 7 fell for a short period at g. In fact WTC 7 does not look like CD, CDs look like gravity collapses because E=mgh, gravity is the primary, the majority of the energy in CD. 911 truth followers fall for the BS of, "looks like CD" and stop thinking.
Ironically if NIST's probable cause is wrong, it was still fire. 911 truth insane claims for thermite, explosives, CD, remain BS born in ignorance.
Do 911 truth follower "chanting thermite, CD, inside job", know the meaning of probable? A discussion of a probable cause, and you are here unable to explain your fantasy cause. Unable to detail what your theory is, unable to more than tangential BS attack on NIST's probable cause, when fire did it even if NIST is wrong. In fact, some engineers disagree with NIST, but fire did it in their probable cause. You have no rational engineers on your side, it is stupid to attack NIST probable cause when all you have to do is your own probable cause. Why can't you do the engineering to detail what you said happened. Why can't you do more then attack NIST? How will you attack the other engineers who say it was fire?
Where is your engineering explanation for WTC 7? Where is your theory? What is the problem, can't you explain your theory?
911 truth has no rational engineers to help with WTC 7. Why did 19 terrorists plant thermite in WTC 7? How did they do it? 911 truth can't prove what you are trying to do, you and 911 truth have zero engineering skill in this area, due to some .
You have no clue if you can prove NIST wrong, it remains fire did it. Your tangential nonsense on WTC 7 and NIST bashing is such a waste as there is no damage to steel from thermite or explosives. 13 years of solid BS born in ignorance is what thermite, CD and explosives are.
Where is your engineering explanation for WTC 7? Where is your theory? What is the problem, can't you explain your theory?
My engineering theory; fire did it. I have never seen a highrise survive fires not fought. In fact, One Meridian Plaza, and Windsor building never survived fires fought. I have examples of fires fought which totaled buildings, and here is 911 truth's faith based followers unable to comprehend WTC 7 was totaled by fire.
Maybe the third time is going to get a response before you Gish Gallop on unable to do nothing to refute NIST's "probable" cause.
Does the interior of WTC 7 collapsing before the exterior fell explain Deets question without the BS of inside job thermite and explosives? Where do you guys get your silent explosives from?
Will you ignore the OP and fail at NIST bashing, or answer the simple questions since you must have a detailed theory on WTC 7 (where is it), or will you answer the simple question Deets had.
Where is your engineering explanation for WTC 7? Where is your theory? What is the problem, can't you explain your theory?
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JayUtah
Penultimate Amazing
Before your first post in his thread I went into some detail about my "authoritative pronouncement" of exactly how those stiffeners worked for the girder in question.
You seem adamant about this, so please go ahead and identify all the unknowns in the problem, show us how you know those are all the unknowns, and then give what you think are reasonable values for those unknowns, and tell us how you arrived at those reasonable estimates.
Yes, this is something of a trick question. And yes, it does seem to do little more than shift the burden of proof. But there's a point to be made, so I hope you'll take it seriously. The point is that "getting into the numbers" rarely means the same thing to engineers on this point as it does to conspiracy theorists.
This is ridiculous and you know it. Running a stat analysis is nothing like setting a computer model simulation of a structure or event. Each simulation is unique and depends on accurate data and analysis. If it is based on inaccurate data or omission of data it is not valid.
Again, if you or anyone else here feels like they can support NIST´s assumption of 6.25 inches of displacement, please take a few minutes and do just that.
You have removed the sentence that preceded it, which was the origin of the ambiguity. Let me put it this way:
Gravity shear loads in a beam were transferred to the bearing seat primarily in the proximity of the web on the bottom flange. Therefore, when the web was no longer supported by the bearing seat, the beam was assumed to have lost support [...] When a girder failed in this manner, the floor beams that it supported were removed at the same time.
See? "in this manner" may well refer to the displacement from the seat, without actually alluding to the lack of stiffness of the bottom flange. That was my point. In this thread and others, at least two more mechanisms for a girder failing when the vertical of its web was off the seat have been provided. That hasn't been addressed by gerrycan or by you, or by any "truther" in general.
That only confirms that they think (as I do) that when the web was off the seat the girder was doomed. It does not confirm your interpretation that it's due to lack of flexural stiffness of the bottom flange.
I merely pointed out the strawman argument that gerrycan set forth, when he declared that the beams could not expand by 6.25 inches. Showing that a premise (that the 6.25" is the expansion of the beams alone) is false does not need me to do any calculations. It's not me who's trying to prove the report as accurate. It's "truthers" who are trying to find a flaw in it by all means.
And you haven't addressed this:
Please either cite where NIST said the stiffener would have no strengthening effect, or take back that accusation.
JayUtah
Penultimate Amazing
The general disinterest among the relevant professions in indulging 9/11 conspiracy theories is not symptomatic of a "touchy subject." Methods and avenues exist for conspiracy theorists to attempt to achieve a similar degree of attention and credibility as have those whom they criticize, but I have yet to see conspiracy theorists make any meaningful attempt to do that. Instead they seem to focus on grass-roots political-style efforts and rely in no small part for sympathy by lamenting on how little attention they're paid for their supposedly legitimate efforts.
Every forensic analysis of a happenstance event must make assumptions for factors which necessarily form part of the phenomena being analyzed, but for which precise evidence is unavailable. I've actually written in some length in this and related threads about these particular assumptions, so I'll leave you to read the threads and see how those concepts have been developed and debated here. I won't repeat them, as I have neither the time nor the inclination.
Your translation of "assumption" to "taken on faith," is not very helpful. It looks like you're loading the language to amp up the emotional value rather than discuss why the assumptions might have been made, how they affect the reliability of the results, and what "scientific" process should have been done instead.
No. Standard engineering practice requires omission of some elements sometimes. You should know that by now. Let me quote a few examples:
Break elements were used on the east side of Floors 7 to 14, where the fires were dominant prior to collapse. Including break elements at every connection location on these floors would have greatly increased the model size and affected the rate of solution convergence. Since the collapse of WTC 7 clearly initiated on the east side of the structure (Chapters 5 and 8), the break elements were only used in the east side of the model.
(NCSTAR 1-9 pp. 457-458)
A procedure was developed for addressing buckled and/or failed components so that any member that did not structurally contribute to the response of the building was removed from the analysis to improve computational efficiency and avoid convergence problems. This procedure was used to modify the model at the end of each 30 min interval, or as necessary when the analysis halted due to non-convergence.
(op.cit. p.487)
In the ANSYS analysis, buckling of flexural members led to convergence difficulties. To improve analysis progress, buckled members were removed from the analysis.
(op.cit. p.487, bottom)
It's up to you to prove that the intent was nefarious. So far NIST has done well justifying their omission: it was not a failure mode contemplated in the model.
JayUtah
Penultimate Amazing
But this is just the same vague, general argument that gerrycan and Tony Szamboti have made. Yeah, it works really well at convincing laymen that NIST is somehow horribly irresponsible for not having maintained a certain level of detail. But it doesn't work very well at convincing the engineering community of it, who are more adept at using and assessing these tools. It's not enough to say "You left this out," or "you made this assumption." The criticism has to show a correct engineering analysis for why the alleged or identified omissions would have affected the analysis in a way that made it an improper basis for the conclusions that included it in their reasoning.
This model, including its simplifying assumptions, were published in the premier peer-reviewed journal for structural engineers. Why wasn't a cry raised there by all the world's structural engineers who rely for their livelihood on getting these methods right? Why, in the nearly 3 years since it was published, haven't Gage's engineers published their rebuttal under similar auspices? Why only now are they getting around to planning their own computer analysis to show how NIST erred? Wouldn't have needed to be done before announcing what the outcome of it would be? Is that scientific?
This changes the burden of proof. You are the one claiming it is entirely unreasonable.
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