Critical Errors and Omissions in WTC7 Report Uncovered

[Mick West]

Thermal expansion rates in steel are not state secrets. The data comes from the structural drawing dimensions, and accepted equations. Where do you think the spreadsheet is wrong. We have had it checked independently, what do you see as a problem with it and why? Do you want to talk to the team who did the analysis with us?

NIST don't make a simple claim along the lines of "beam A expanded by X". They ran a couple of different highly complex simulations, the results of which were that the girder fell off the seat. In the more detailed local simulation, the girder was twisted and rocked off its seat. Renderings of this failure are given. In the larger global simulation the end result was that the girder was unseated, and this was described as the girder being walked off by the expansion of the beams. However what actually happened to the girder and the individual is not described. No renderings are given.

Gerry makes the case that there were inaccuracies in the NIST report. A stiffener plate is missing from a diagram (and NIST have said nothing about it). A width is specified as 11" rather than 12" (since corrected). On a simplistic level of just considering one beam pushing a girder a certain distance in one dimension then these inaccuracies would seem to make a difference. But we don't know if these inaccuracies are in the actual model used, of if they are simply omissions and errors in the report itself. [Edit: actually the correct distance was used in the analyses, as RP notes below] We also don't know what difference [the stiffener plate] would make to the actual simulations.

What we DO know is that the simulations identified plausible failure modes for this type of building.

 

[Representative Press]

1. The new distance they quoted was actually 6.25"

They don't say "new," NIST says it is the correct value to reflect what the value they had been using all along in their
analyses. They didn't change their model or calculations, they just fixed a typo. But the error in the typo was not the value that they had used in their analyses: "...
This change corrects a typographical error which showed a lateral displacement of 5.5 in. instead of the correct value of 6.25 in., which was used in the analyses.""
"...
These changes correct typographical errors. The dimensions and lateral displacements used in the analyses were correct."

 

[Representative Press]

What gerry's research appears to have uncovered is evidence that NIST reached the conclusion about the column 79 floor 13 initiation event based on incorrect data

That's not what appears to have happened, it certainly isn't what NIST said. NIST did not say they changed any values in their analyses:
https://www.metabunk.org/threads/critical-errors-and-omissions-in-wtc7-report-uncovered.2332/page-9#post-69413

 

[Hitstirrer]

Mick - As you correctly identify, we don't know if the inaccuracies were used in the model or just in the words of the report. That is why many attempts have been made to obtain their input data so that it could be peer reviewed by running it through similar programmes. As you will know, NIST has refused all such FOIA requests using the 'catch-all' excuse that it would jeapardise public safety.
In one court action contesting this decision, they clarified that such data could be used to assist others in planning the destruction of a different high-rise building.
Quite how the highly specific data on a now non existant building could be used by potential terrorists to identify weaknesses in a totally different building is what I don't understand, but obviously judges who reject all appeals must consider that feasable.
But for you to go on to say that " What we DO know is that the simulations identified plausible failure modes for this type of building" I find that a leap too far.
Finding a plausible failure mode for the very first such global collapse based on one single connection initiating event when the elements shown are inaccurate hardly leads me to use the word plausible.
And all this could be cleared up very rapidly by NIST releasing their input data. At which point we would see whether they included stiffeners in their girder analysis or not. Then other organisations could re-run that data through their own machines and verify whether NIST's claimed single connection initiation failure was accurate or not.
Meanwhile, according to gerry, NIST have not yet acknowledged the existance of the stiffeners which he is focussing on. That failure to respond does not help their cause, as more and more building professionals exposed to this information use phrases like " Its a game changer".

 

[Mick West]

Meanwhile, according to gerry, NIST have not yet acknowledged the existance of the stiffeners which he is focussing on. That failure to respond does not help their cause, as more and more building professionals exposed to this information use phrases like " Its a game changer".

More and more people like Tony Szamboti, who were already convinced the NIST analysis was rigged.

 

[Hitstirrer]

That's not what appears to have happened, it certainly isn't what NIST said. NIST did not say they changed any values in their analyses:
https://www.metabunk.org/threads/critical-errors-and-omissions-in-wtc7-report-uncovered.2332/page-9#post-69413

The incorrect data referred to isn't the two 'convenient self cancelling' typos. The incorrect data is the absence of stiffener plates which render their 'corrected' figure of 6.25" irelevent as a move of more like 9" or 10" would be required to enable that girder to be moved laterally from its seat.

 

[Jazzy]

All this talk of girders, flanges and slippage is fascinating but can everyone agree that WTC7 fell at free fall speed for close to 5 seconds? That's what NIST says.

How can that happen if a beam or girder slips?

It happens to any loaded slender vertical steel column if it loses contact with the floors that laterally stabilize it. One floor disconnected, and its resistance to buckling instability falls to an eighth of its previous value (at the fire temperature). Two floors disconnected, and that factor becomes one eighteenth.

That's past the building safety factor, and not counting the strong likelihood of the centerline of Column 79 already having "crept" off its axis.

Once a slender vertical steel column fails, its downward acceleration is almost G. It literally "disappears" from the structural equations, and the remaining structure becomes a mechanism for load transferral, and the structure above that column descends, as it becomes a load cantilevered off all the surrounding columns.*

All the existing static civil equations only apply to a structure truly horizontal and vertical, and cool. Euler's equation follows this rule too. That safety factor was easily overcome.

The lesson to be drawn from this is that reinforced concrete is considerably safer from fire than insulated steel, due to its other properties like lessened creep and elasticity, and increased insulation cover, joint rigidity, damping and load-spreading ability.

* The structure below the failed Column 79 will deflect upwards, of course, as the part-load of 33 floors is removed from the non-failed part of the Column 79 beneath its failure point, and it springs upward.

 

[Hitstirrer]

More and more people like Tony Zamboti, who were already convinced the NIST analysis was rigged.

Correct. But I do hope that you are not hinting that Tony Szamboti is being less than professional with that opinion.

Gerry had indicated that the information has been presented to other Engineers who have all without exception reached the same conclusion. That is that the connection in question , if fitted with the elements as shown on the drawings, (but omitted from NIST's version ) would not fail in the manner claimed due to either 'push off' or 'rock off', using NIST's own temperature data.

 

[Mick West]

The incorrect data referred to isn't the two 'convenient self cancelling' typos. The incorrect data is the absence of stiffener plates which render their 'corrected' figure of 6.25" irelevent as a move of more like 9" or 10" would be required to enable that girder to be moved laterally from its seat.

You mean "for the connection to fail", not "to enable that girder to be moved laterally from its seat."

Seems like there is a bit of hand waving here. You are saying that a connetion that is supposed to be this:

Would be perfectly fine like:

Or more realistically:

Or:

And that's not even accounting for the other damage that was going, possible other falling beams. Other failed or failing connections.

Your analysis is highly one dimensional and simplistic. The actual situation was much more complex.

 

[Jazzy]

we don't know if the inaccuracies were used in the model or just in the words of the report. That is why many attempts have been made to obtain their input data so that it could be peer reviewed by running it through similar programs. As you will know, NIST has refused all such FOIA requests using the 'catch-all' excuse that it would jeopardise public safety. In one court action contesting this decision, they clarified that such data could be used to assist others in planning the destruction of a different high-rise building. Quite how the highly specific data on a now non existent building could be used by potential terrorists to identify weaknesses in a totally different building is what I don't understand, but obviously judges who reject all appeals must consider that feasible.

That seems reasonable to me.

But for you to go on to say that " What we DO know is that the simulations identified plausible failure modes for this type of building" I find that a leap too far. Finding a plausible failure mode for the very first such global collapse based on one single connection initiating event when the elements shown are inaccurate hardly leads me to use the word plausible. And all this could be cleared up very rapidly by NIST releasing their input data. At which point we would see whether they included stiffeners in their girder analysis or not. Then other organizations could re-run that data through their own machines and verify whether NIST's claimed single connection initiation failure was accurate or not.

As I have said before, it is close to accurate, and stiffener plates wouldn't make any significant difference.

Engineers have all without exception reached the same conclusion. That is that the connection in question, if fitted with the elements as shown on the drawings, (but omitted from NIST's version) would not fail in the manner claimed due to either 'push off' or 'rock off', using NIST's own temperature data.

I would agree too, but that "analysis" bears no relation to what REALLY happened at Floor 13, Column 79, in 7 WTC, on 9-11.

You mean "for the connection to fail", not "to enable that girder to be moved laterally from its seat." Seems like there is a bit of hand waving here. Your analysis is highly one dimensional and simplistic. The actual situation was much more complex.

Finally.

 

[Hitstirrer]

You mean "for the connection to fail", not "to enable that girder to be moved laterally from its seat."

Seems like there is a bit of hand waving here. You are saying that a connetion that is supposed to be this:
View attachment 4409

Would be perfectly fine like:
View attachment 4410

Or more realistically:
View attachment 4411

Or:
View attachment 4412

And that's not even accounting for the other damage that was going, possible other falling beams. Other failed or failing connections.

Your analysis is highly one dimensional and simplistic. The actual situation was much more complex.

No handwaving going on at all.

I am quoting NIST's explanation rather than your own imagined scenario. If you recall, it is NIST who claim either lateral walk-off of (now) 6.25", or rock-off using that same lateral displacement. If we are to consider every imagined scenario rather than the one actually put forward by the official report then we would have a multitude of theories to debate. I prefer to address the official report and see if it stands scrutiny.

But you have now introduced web flexing to suggest some kind of warping action to negate a simple lateral move. Such speculation would require you to substantiate the large deflections in that girder by calculations. Do you have those ? And you have failed to show in your drawings that five beams are still attached to that girder which would strongly resist such warping as you show.

I am very well aware that the interaction of all elements in and around this suggested failure point would be very complex. But as NIST has reduced it to a simplistic single connection failure i feel able to be equally simplistic in looking closely at that simplistic claim. NIST did not say that the interaction was so complex that it was impossible to be specific. They were specific. And in doing so allow me to challenge that simplistic conclusion.

If that subsequently causes much controversy then surely such a highly respected body would wish to prove their case by release of the data showing that their computer simulation was accurate. By not doing so they lay themselves open to such challenges of their simplistic failure conclusion, because people like you and I know instinctively that the real cause of such a global collapse would have had to be far more complicated than they imply.

That leaves their report smacking of being written to satisfy the unquestioning masses rather than reaching a real scientific conclusion.

 

[Mick West]

No handwaving going on at all.

I am quoting NIST's explanation rather than your own imagined scenario. If you recall, it is NIST who claim either lateral walk-off of (now) 6.25", or rock-off using that same lateral displacement. If we are to consider every imagined scenario rather than the one actually put forward by the official report then we would have a multitude of theories to debate. I prefer to address the official report and see if it stands scrutiny.

But you have now introduced web flexing to suggest some kind of warping action to negate a simple lateral move. Such speculation would require you to substantiate the large deflections in that girder by calculations. Do you have those ? And you have failed to show in your drawings that five beams are still attached to that girder which would strongly resist such warping as you show.

Unless they contributed to it, by their own expansion and sagging.

I am very well aware that the interaction of all elements in and around this suggested failure point would be very complex. But as NIST has reduced it to a simplistic single connection failure i feel able to be equally simplistic in looking closely at that simplistic claim. NIST did not say that the interaction was so complex that it was impossible to be specific. They were specific. And in doing so allow me to challenge that simplistic conclusion.

If that subsequently causes much controversy then surely such a highly respected body would wish to prove their case by release of the data showing that their computer simulation was accurate. By not doing so they lay themselves open to such challenges of their simplistic failure conclusion, because people like you and I know instinctively that the real cause of such a global collapse would have had to be far more complicated than they imply.

That leaves their report smacking of being written to satisfy the unquestioning masses rather than reaching a real scientific conclusion.

The unquestioning masses have not read the report. But I'm unsure what you mean by "far more complicated than they imply". The hundreds of pages of damage analysis and the litany of damaged connections and beams in the report seems jolly complicated to me. It's your hinging of everything on the stiffener plates in the hypothetical initiating event that's an oversimplification.

 

[qed]

I have been trying to get the NIST reports to inform myself on this topic, but,

Due to a lapse in government funding, the National Institute of Standards and Technology (NIST) is closed and most NIST and affiliated web sites are unavailable until further notice. We sincerely regret the inconvenience.

http://wtc.nist.gov/NCSTAR1/

NIST, NASA and Computer Security Resource Center (CSRC) are all gone! http://grahamcluley.com/2013/10/barack-obama-nasa-nist-government-shutdown/

Does anyone know where duplicates may be obtained online?

 

[Hitstirrer]

Mick - But it is simple.

After millions of separate data inputs NIST concludes by saying that, whatever the means, what happened was that one girder on floor 13 dropped onto floor 12 and that went on to cause global collapse.

That is their simple claim.

Its not me being simplistic - its NIST.

And unless they can prove by release of their calculations and data input that the girder can indeed fall onto floor 12, such a simple claim will continue to be challenged.

You and I may know that such a simple claim doesnt go anywhere near explaining this event fully.

But thats what NIST said. Please address your 'oversimplification' comments to them.

 

[Mick West]

Mick - But it is simple.

After millions of separate data inputs NIST concludes by saying that, whatever the means, what happened was that one girder on floor 13 dropped onto floor 12 and that went on to cause global collapse.

That is their simple claim.

Its not me being simplistic - its NIST.

And unless they can prove by release of their calculations and data input that the girder can indeed fall onto floor 12, such a simple claim will continue to be challenged.

You and I may know that such a simple claim doesnt go anywhere near explaining this event fully.

But thats what NIST said. Please address your 'oversimplification' comments to them.

That's not what they are saying.

They are saying that the fire did a lot of damage, and the build collapsed because of that damage. It looked like the collapse was caused by the failure of column 79, and they identified one possible sequence of events that might have caused it. The title of the report is:

"Structural Fire Response and Probable Collapse Sequence of World Trade Center Building 7"

not

"This is exactly what happened down to the last inch!!!"

 

[Hitstirrer]

That's not what they are saying.

They are saying that the fire did a lot of damage, and the build collapsed because of that damage. It looked like the collapse was caused by the failure of column 79, and they identified one possible sequence of events that might have caused it. The title of the report is:

"Structural Fire Response and Probable Collapse Sequence of World Trade Center Building 7"

not

"This is exactly what happened down to the last inch!!!"

 

[Hitstirrer]

Mick Sorry - I havn't learned how to 'drive' this forum yet.

Meant to say :-

Actually the report I am reading is titled " Final report on the Collapse of World Trade Center Building 7 "

You can access it here. http://s3.amazonaws.com/nasathermalimages/public/images/NCSTAR 1A_unlocked.pdf

 

[Hitstirrer]

That seems reasonable to me.


As I have said before, it is close to accurate, and stiffener plates wouldn't make any significant difference.


I would agree too, but that "analysis" bears no relation to what REALLY happened at Floor 13, Column 79, in 7 WTC, on 9-11.


Finally.

So what we need now is your own explanation of 'what REALLY happened'.

But please bear in mind that you will be out on a limb on your own unless you fully concur with NIST's analysis - that a girder on floor 13 dropped onto floor 12. Because that is what we have been told happened by the worlds most expert analysts.

And if stiffener plates ' wouldn't make any significant difference' - please give your calculations to support that bare assertion.

I await your explanation with interest.

 

[Hitstirrer]

I have been trying to get the NIST reports to inform myself on this topic, but,

Due to a lapse in government funding, the National Institute of Standards and Technology (NIST) is closed and most NIST and affiliated web sites are unavailable until further notice. We sincerely regret the inconvenience.

http://wtc.nist.gov/NCSTAR1/

NIST, NASA and Computer Security Resource Center (CSRC) are all gone! http://grahamcluley.com/2013/10/barack-obama-nasa-nist-government-shutdown/

Does anyone know where duplicates may be obtained online?

Here :- http://s3.amazonaws.com/nasathermalimages/public/images/NCSTAR 1A_unlocked.pdf

 

[Mick West]

Mick Sorry - I havn't learned how to 'drive' this forum yet.

Meant to say :-

Actually the report I am reading is titled " Final report on the Collapse of World Trade Center Building 7 "

You can access it here. http://s3.amazonaws.com/nasathermalimages/public/images/NCSTAR 1A_unlocked.pdf

Well you should read "Structural Fire Response and Probable Collapse Sequence of World Trade Center Building 7", because it's a lot more detailed and it is incorporated into NCSTAR 1-A by reference.

Here:
https://www.metabunk.org/files/NCSTAR_1-9_WTC7_unlocked.pdf

 

[qed]

@Mick West

You have claimed in other threads that the NIST report is "internally consistent".

Has Gerry demonstrated an internal inconsistency? Or, is it the case that with the typographical correction, there is no inconsistency?

I have not read the report properly and so cannot comment.

 

[Mick West]

@Mick West

You have claimed in other threads that the NIST report is "internally consistent".

Has Gerry demonstrated an internal inconsistency? Or, is it the case that with the typographical correction, there is no inconsistency?

I have not read the report properly and so cannot comment.

He's demonstrated a possible omission of stiffener plates from the consideration of the failure criteria for the Col 79 girder connection.

When I said it was "internally consistent", I was contrasting it to Marcus Mudd's observation that it was inconsistent with some eyewitness testimony. (Which is inevitable as eyewitnesses are inconsistent with each other).
https://www.metabunk.org/threads/pr...olated-pockets-of-fire.2079/page-2#post-62634

 

[qed]

He's demonstrated a possible omission of stiffener plates from the consideration of the failure criteria for the Col 79 girder connection.

Why a "possible omission" rather than a definite omission?

 

[Hitstirrer]

Well you should read "Structural Fire Response and Probable Collapse Sequence of World Trade Center Building 7", because it's a lot more detailed and it is incorporated into NCSTAR 1-A by reference.

Here:
https://www.metabunk.org/files/NCSTAR_1-9_WTC7_unlocked.pdf

Oh - I have read that as well. As you say it is very detailed.

The problem is that essential detail is wrong. Take a look at page 559 - Figure 12-25. It models the girder being discussed there. As you will see, it has the whole connection wrong. The underseat plate is not there. Instead there is a 'shelf' type bracket that is far weaker than the real element. There are no side plates on the column. And - errr - no stiffeners on the girder end.

And then the 'detailed' conclusion from the 'Probable collapse' document about that connection failing and leading to the girder dropping onto floor 12 is carried forward to the Final Report.

See page 39 in the final report. :-

"Figure 2-2 shows the structural response of WTC 7 to the fire-induced damage on the east side. Floor 13 collapsed onto the floors below, causing a cascade of floor failures down to Floor 5. The floor failures left Column 79 laterally unsupported and it buckled, which was quickly followed by the buckling of Columns 80 and 81."

So an extremely detailed conclusion based on incorrect input makes a simple statement in the final report.

There is a well known term called GIGO that could apply here.

This thread is examining gerry's contention that floor 13 could not drop onto floor 12 if the correct elements had been used in the 'detailed' probable collapse analysis. And if that couldn't happen then column 79 could not have buckled.

So. whilst I take your point about the report not being titled :- "This is exactly what happened down to the last inch!!!", I would have expected it be reasonably accurate when identifying the initiation event. They did report in both the ' Probable collapse' and 'Final report' that the entire global collapse began by a single girder on floor 13 dropping onto floor 12.

There is no denying that.

And if their entire theory is based on a single connection that isn't modelled correctly in their report surely its reasonable to ask them to justify that to the people. Especially when they subsequently refuse to acknowledge the existence of those stiffeners that have such a devastating effect on their calculations.

We can all put forward our own theories and point out that it is far more complicated than that, but the bottom line is that NIST examined all those complications and concluded that it was a single girder dropping off a seat that caused this event.

And if floor 13 could not drop onto floor 12 then another reason for column 79 buckling has to be put forward. Gerry's input would suggest that there is much doubt about NIST's assertion.

 

[Mick West]

Do you doubt that column 79 buckled?

Do you doubt that there was quite significant damage to the floor beams, girders and connections on floor 13 and several other floors?

 

[qed]

@Mick West

I don't understand. You are answering questions with questions?

You said "He's demonstrated a possible omission of stiffener plates from the consideration of the failure criteria for the Col 79 girder connection."

and I merely asked why that cannot be strengthened to

"He's demonstrated an omission of stiffener plates from the consideration of the failure criteria for the Col 79 girder connection."

Why can't it?

 

[jomper]

More and more people like Tony Szamboti, who were already convinced the NIST analysis was rigged.

Your point, sir? You understand the importance of falsifiability in the scientific method I'm sure?

The NIST model is obviously not in a category of claim that Popper identified as being unfalsifiable.

 

[Mick West]

@Mick West

I don't understand. You are answering questions with questions?

Sorry, I was responding to hitstirrer, who did not ask questions.

You said "He's demonstrated a possible omission of stiffener plates from the consideration of the failure criteria for the Col 79 girder connection."

and I merely asked why that cannot be strengthened to

"He's demonstrated an omission of stiffener plates from the consideration of the failure criteria for the Col 79 girder connection."

Why can't it?

Because we don't know if they would actually effect the failure criteria that was used. We don't know if they were considered in establishing that criteria.

 

[Mick West]

Your point, sir? You understand the importance of falsifiability in the scientific method I'm sure?

The NIST model is obviously not in a category of claim that Popper identified as being unfalsifiable.

My point is that it's an argument from false authority to quote Szamboti and attribute his comments to "more and more building professionals ". Falsifiability has nothing to do with that point.

 

[qed]

Your point, sir? You understand the importance of falsifiability in the scientific method I'm sure?

The NIST model is obviously not in a category of claim that Popper identified as being unfalsifiable.

It may be possible to demonstrate internal inconsistency which will render it mathematically valueless (on top of the scientific worthlessness by non unfalsifiability).

 

[qed]

Because we don't know if they would actually effect the failure criteria that was used. We don't know if they were considered in establishing that criteria.

So you are saying that, despite the inconsistency between parts of the report, it is still possible that the report is valid?

 

[Mick West]

It may be possible to demonstrate internal inconsistency which will render it mathematically valueless (on top of the scientific worthlessness by non unfalsifiability).

The characterization of the report as a fragile mathematical proof is just wishful thinking. You don't invalidate the entire thing by adding a stiffener plate. It simply casts slightly more doubt on the (already hypothetical) initiating event.

 

[gerrycan]

You mean "for the connection to fail", not "to enable that girder to be moved laterally from its seat."

Seems like there is a bit of hand waving here. You are saying that a connetion that is supposed to be this:
View attachment 4409

Would be perfectly fine like:
View attachment 4410

Or more realistically:
View attachment 4411

Or:
View attachment 4412

And that's not even accounting for the other damage that was going, possible other falling beams. Other failed or failing connections.

Your analysis is highly one dimensional and simplistic. The actual situation was much more complex.

Mick, you need to be backing this up with some engineering analysis. There is just no way that the girder end could do this. I think you should either explain or withdraw this nonsense that has no basis in terms of engineering and shows an apparent huge void in your understanding of this connection and the elements around it, and therefor engineering issues in general. You have been fair in this thread and I admire the way that you have dealt with issues and addressed them in general, but this type of blind assertion with nothing whatsoever to back it up lets you down totally. It makes you look desperate, and you are actually raising some interesting points elsewhere, there's no need for you to resort to this nonsense.
Please explain to the forum how this kind of distortion occurred in the girder. Have you any idea the kind of loads and forces that this kind of distortion in the girder would require? Please qualify this assertion.

 

[Mick West]

So you are saying that, despite the inconsistency between parts of the report, it is still possible that the report is valid?

What inconsistency? You mean the (consistent) omission of the plate? Like I said, it simply casts slightly more doubt on the (already hypothetical) initiating event.

 

[jomper]

My point is that it's an argument from false authority to quote Szamboti and attribute his comments to "more and more building professionals ". Falsifiability has nothing to do with that point.

However falsifiability is precisely what's required to address Szamboti's concerns. This is only what the scientific method demands.

 

[Mick West]

Mick, you need to be backing this up with some engineering analysis. There is just no way that the girder end could do this. I think you should either explain or withdraw this nonsense that has no basis in terms of engineering and shows an apparent huge void in your understanding of this connection and the elements around it, and therefor engineering issues in general. You have been fair in this thread and I admire the way that you have dealt with issues and addressed them in general, but this type of blind assertion with nothing whatsoever to back it up lets you down totally. It makes you look desperate, and you are actually raising some interesting points elsewhere, there's no need for you to resort to this nonsense.
Please explain to the forum how this kind of distortion occurred in the girder. Have you any idea the kind of loads and forces that this kind of distortion in the girder would require? Please qualify this assertion.

It's an artists impression, not a physical based rendering. I roughly based it on:

I thinking there would be a range of heating order/amount scenarios, so a variety of girder distortion scenarios.

 

[gerrycan]

The characterization of the report as a fragile mathematical proof is just wishful thinking. You don't invalidate the entire thing by adding a stiffener plate. It simply casts slightly more doubt on the (already hypothetical) initiating event.

It invalidates the initiating event and makes it impossible for the collapse to have initiated in the manner that NIST claim that it did. Explain the 'fragile mathematical proof' to me, what is it? Let's see some numbers please, so we can check.

 

[qed]

I will accept

It simply casts slightly more doubt on the (already hypothetical) initiating event.

 

[Mick West]

However falsifiability is precisely what's required to address Szamboti's concerns. This is only what the scientific method demands.

But you could say that about any concerns. It does not make the concerns more valid.

 

[Hitstirrer]

Do you doubt that column 79 buckled?

Do you doubt that there was quite significant damage to the floor beams, girders and connections on floor 13 and several other floors?

Those questions lead to pure speculation. I prefer to focus on what we have been told caused this global collapse. Clearly, from the videos we see, the penthouse was the first sign of any lack of lower support in the building, and as column 79 was the prime support to the penthouse, then it is logical to look closely there. That is what NIST did.

Their problem was to then translate the observed visual evidence of the penthouse dropping rapidly, into a subsequent global collapse of the entire building. No wonder that they struggled for years and remarked that they 'couldnt get a handle on it'.

To address the elephant in the room, many people claim that some kind of alternative means were used to achieve that global collapse. To be fair, NIST did address that but concluded that as there were no reports of huge explosions they could discard the possibility. (What I find amusing over that remark is that they then go on to claim that a single girder dropping, relatively soundlessly, caused the very event that they previously claimed would have required a MASSIVE explosion ). And then of course there are numerous reports of large explosions that were ignored by NIST.

But such speculation takes us off topic.

To answer your questions directly.

I do have grave doubts about the claimed girder drop event that NIST then use to go on to claim caused all the lower lateral support to column 79 and led to it buckling. My reason for these doubts is a combination of gerry's input, but also a close look at the various simulations released by NIST which, when analysed frame by frame to follow individual girders and beams, do not support their claimed progression scenario. Such analysis can be looked at in another thread though.

Even assuming their 79 buckling is accurate I then find it hard to follow their claim that it then led to such a very symmetrical collapse. But again that leads off topic of this thread.