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'What about building 7'?

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LSSBB said:
Wrong, try again.
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In terms of what NIST are saying it isn't. They're basically saying that to include the impacts of failed elements on floors in the model would have made the check calculation to run the model too large to allow it to be done quickly enough.
 
gerrycan said:
In terms of what NIST are saying it isn't. They're basically saying that to include the impacts of failed elements on floors in the model would have made the check calculation to run the model too large to allow it to be done quickly enough.
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What you are just saying does not relate to what you posted regarding load balance.
 
LSSBB said:
Wrong, try again.

ETA: Start with wiki here, then keep digging until you see daylight. The best way to experience the true meaning is develop your own algorithm to solve a problem then watch it get nowhere all night, in frustration.
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Success is born out of experience. Experience is born out of failure.
 
gerrycan said:
Where's the explanation as to how the girder framing into c79 from the west manages to push the column to the east, and what is more managed to do it without damaging its connections at all at either end. This should be addressed.
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Do my eyes deceive me? Gerry is acknowledging that the NIST fea has the col 79 deforming due to girder expansion between it and col 76(iirc).

It goes one way, girder to col 44 moves the opposite way. Both contribute to girder coming off its seat.
 
gerrycan said:
Very informative. Thanks.
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You're welcome.

LSSBB said:
That's a good article for reference. Computing power has of course increased, and advanced techniques and algoritms less subject to iterative error have been developed, however the basic concept remains.
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Yes. Take away from this is FEA is a tool that needs competent users. The NIST explains it's reasoning for inputs very well.

Where "truthers" are failing is they're not addressing the NIST justification and methods themselves only the fact they differ from reality. This is not in line with competent use of FEA.
 
gerrycan said:
Whether the intent was nefarious or not does not trouble me too much. How accurately the buildings response to the imposed conditions does though.
The judgement that an element such as this girder had failed and would therefore be removed (as would every beam connecting to it in this particular instance) was determined outside of ansys and that determination was applied to the ansys model. The stiffener plates should have been accounted for in NISTs initial assessment and that determination applied to the model. To account for the presence of the plates and the difference they would make to the analysis is not a problem for ansys. Whether the decision not to account for these plates was nefarious or just a mistake has no bearing on the accuracy of the report. The difference that the accounting for these plates would have made does not depend on the intention of NIST and we know from them that these plates was not considered.
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Excluding the part that I have greyed, I agree, except for the false dilemma on "nefarious or just a mistake". It can also have been a sound decision. You're excluding that possibility and I think you shouldn't.


gerrycan said:
I don't see a great amount of data being saved by not accounting for the stiffener plates and even if it was a potentially data intensive issue to include them, I don't see how anyone could argue against their inclusion given that this is the connection at the heart of NISTs hypothesis.
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I don't think you are actually thinking about what you are saying here. Inclusion in the FEA itself makes no sense. If they did what you're asking here, the model would need to include the top and bottom flange, torsional forces that they said caused convergence problems, and all sorts of analysis, just for determining whether the girder failed in a certain way. They ran a whole one-floor FEA just for that, to not have to do that analysis later in ANSYS.


gerrycan said:
As for the failure mode not being contemplated in the model, I agree with you there.
The difference that these plates would have made to the connection was not contemplated by NIST. They have admitted the exclusion of elements without justifying the decision not to account for them in the analysis.
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They justified it, you just don't like the answer.

The right question here is:

Is it reasonable to consider a girder failed when its web is off its seat, even if there are web stiffener plates welded to the bottom flange?

Rather than jumping to conclusions, or doing incomplete analysis that doesn't account for several important factors, you should actually seek an answer to that question by competent specialists. Two engineers here have already provided mechanisms by which a girder in that situation would be unstable enough that considering it as failed would be reasonable. One was Newton's Bit, who said the girder could roll off, and another was JayUtah, who said the web could buckle. [Edit: I invite both to correct me if they feel I'm misrepresenting their positions.]

Now you can say that there's bias in these assessments. And I would say the same for any engineer who thinks WTC7 may have been a controlled demolition. So in order to get a sound response, the best you can do is ask neutral engineers. If the overwhelming majority said that it's not sound practice to do that, then you would have grounds for saying that the omission of the stiffeners in NIST's analysis was a mistake.

That, of course, assumes that your (gerrycan's) actual intention is the one you declare it is, which given the "gameplan" posted by forum member Ape of Good Hope in page 79, I have reasons to doubt.
 
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JayUtah said:
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.
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Actually it doesn't work very well at convincing laymen. Joe Average Citizen, to the extent that he pays any attention to WTC 7, first finds that the fires were the largest in history and that FDNY cleared a safety zone around it, fearing collapse.

The fact that it DID collapse merely proves to Joe that FDNY made a good call, and Joe leaves it at that, any further discussion to be left to professionals.

A suspicious person might suspect that AE911T's strategy of pitching to laymen instead of professionals is "designed to fail", intended only as a way of collecting money from the usual conspiracy paranoiacs. :rolleyes:
 
...You have removed the sentence that preceded it, which was the origin of the ambiguity. Let me put it this way:

...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.

...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.
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Pgimeno, you are trying to obfuscate a very simple thing which is very clearly stated by NIST in chapter 11/page 488. It gives two possible modes of walk off failure:

1) by axial movement 2) by lateral movement.

No matter how much you try to confuse the issue, it is comletely obvious that the axial/straight forward or backwards movement of a beam or a girder will not push it to the side and leave it resting on only one side; only the second choice, the lateral/sideways movement, will leave a beam or girder resting on only one side/that one flange on that side.

And page 488 goes on to explain that the failure mode of option 2, the lateral walk off, is by the lack of flexural stiffness of that one flange.

There is absolutely no ambiguity here unless someone tries to create it by quoting selected parts out of context.

The only question is whether or not the walk off scenario at the 44-79 girder is by 1) axial displacement or 2) lateral displacement.

And again, NIST very clearly answers this question in chapter 11/page 525:

"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."

Chapter 11 therefore concludes that the girder en at column 79 walked off the seat once the girder had somehow been displaced sideways/laterally 6.25 inches, at which point it was only resting on that one bottom flange on one side of the girder, which consequently folds due to lack of "flexural stiffness".
 
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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.
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Pgimeno, a serious researcher is not inclined to do that on a forum such as this one, because you people try to conflate NIST´s story for the walk off at column 79 with your own distorted versions of NIST´s story, which you of course declare to be correct on your own forum. I am not interested in your pet theories, I just want to see if anyone here can actually justify NIST´s walk off theory with actual data and numbers.
 
Ziggi said:
Pgimeno, you are trying to obfuscate ...".
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Why do your posts fail to support your CD claims you are afraid to state or support. You can't prove your theory by exposing the lack of engineering 911 truth uses to fool the faith based 911 truth followers.

But the OP is pretty narrow, unlike the Gish Gallop 911 truth followers love, a single step of the Gish Gallop 911 truth handbook.

dadeets said:
... how can there be 2.25 seconds of free fall at Building 7 without some additional energy source removing 8 stories of structure abruptly from beneath the upper structure?
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The answer to the OP is, the interior of WTC 7 was collapsing 6 seconds before bringing down the roof-line. Why does 911 truth ignore evidence, facts?

Why can't you comment on the OP?

A serious researcher does not attack other work, a serious researcher does his own work and posts evidence to support their work: your only tactic is to attack a probable cause; and you are incapable of supporting your inside job BS, your CD fantasy, your fraud of thermite, and the silent explosives nonsense. You need NIST to spin a failed attack, based on opinions, you offer no math or engineer, only talk.

And.
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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Just more of the same troofer hamster wheel. Trying to set limits to the "debate" make demands, and be the sole judge of what is valid and acceptable......(it makes it easy to run back to trooferville and claim victory)

Same song and dance <YAWN>
 
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