Merged Discussion of femr's video data analysis

[femr2]

I am compelled to spend time on something that I do not follow closely. I am sure there is a logical contradiction there somewhere.

I am sure there is, especially when you complain about individual post transparency. You expect each post to reinvent the wheel for your convenience ? Think again.

you have no clear purpose at all to do so.

Incorrect.

I do no believe there is a significant 'problem' so I am content to not have millions more spent on insignificant details.

Then why complain ?

You on the other hand seem quite of the opposite view

What gave you that idea ? (Quotes are always handy in that context)

come up with a collapse sequence that aligns in more detail with what was observed (in the NIST FEA).

Well there's an idea.

 

[leftysergeant]

Why an oscillation and not a non-recovering displacement ?

Steel is kind of springy.

You have a hot girder pushing against a column because the grider is expanding. The column moves over. Two things can happen next.

1. The girder stays hot and continues to expand until it begins to lose structural strength. It begins to buckle. The column pushes back and returns to its original poistion.

2. The fire moves on to another fuel source and the girder starts to shrink. The column is allowed to move back to its original position.

Of course, in either of these sceanrios, a lot of stress has been placed on other connections in the structure and some SFRM has been removed by warpping the steel under it. I do not now expect those other joins to hold up at all as well as they did during the expansion and contraction of the girder and the rebounding of the column.

My point is that, if there were oscillations of any sort during the fire, it is evidence that the collapse was of a progressive nature, in no way assisted by HE or thermite. The building stretched itself to death.

Think you are getting well ahead of yourself there. You've provided speculative behaviour, but are now stating how that minor fluctuation is illustrative. It's not, it's still speculation. Failure of floor 13 could have zero effect.

Minor fluctuations are, of course, evidence that it was not CD. CD initiates a lot of changes at once, quite suddenly and almostv immediately catastrophicly.

 

[femr2]

Steel is kind of springy.

The motion is global, over period of ~100 seconds.

Did you make sure you read the scope of the question in hand ?

 

[leftysergeant]

The motion is global, over period of ~100 seconds.

Did you make sure you read the scope of the question in hand ?

Forces applied to a single key element inside a structure can cause a global movement.

Everything is kind of tied together in the end, if not immediately.

 

[jaydeehess]

I am sure there is, especially when you complain about individual post transparency. You expect each post to reinvent the wheel for your convenience ? Think again.

Nope, about a dozen words actually outlining what you refer to would do.

Incorrect.

Another precise reply.
Let's try again then. What is your clear purpose?

Then why complain ?

Me complain. I seem to recall you going on a few times about how NIST was wrong here or there. So my complaint would be with you IF you are saying that NIST did not do enough work on this.

What gave you that idea ? (Quotes are always handy in that context)

I'm sorry, you also do not believe that there is a significant problemhere that requires all that you are posting in this thread? Quoting most of your comments in this thread to illustrate why i thought you believed there was something significant to investigate is probably not in the best interests of the JREF site.

Well there's an idea.

the question was;
"I asked YOU if YOU think NIST should (ie. is there a particularily compelling arguement to be made for, and if so what is it) re-run the FEA hundreds of times adjusting combinations of parameters to come up with a collapse sequence that aligns in more detail with what was observed.


So to be clear your answer to the question is a 'yes'?

 

[jaydeehess]

Why do I get the feeling I am trying to nail Jell-o to a door?

 

[jaydeehess]

The motion is global, over period of ~100 seconds.

Did you make sure you read the scope of the question in hand ?

Forces applied to a single key element inside a structure can cause a global movement.

Everything is kind of tied together in the end, if not immediately.

I tried to illustrate this with the analogy of a rope tied to a tree. However it seems(one can never seem to tell what femr really thinks) that he expects local events to cause strictly local effects.

 

[femr2]

Nope, about a dozen words actually outlining what you refer to would do.

I quoted the entire lead-up discussion. Still not enough for you I guess

What is your clear purpose?

In the context of this thread, analyse motion in video of WTC 1, 2 & 7.

IF you are saying that NIST did not do enough work on this.

Enough work ? Irrelevant. Questionable results, sure.

you also do not believe that there is a significant problem here

Incorrect. I have no immediate intention to *write a paper to be submitted to a peer-reviewed journal* or *contact NIST*. If you want to, go ahead.

"I asked YOU if YOU think NIST should (ie. is there a particularily compelling arguement to be made for, and if so what is it) re-run the FEA hundreds of times adjusting combinations of parameters to come up with a collapse sequence that aligns in more detail with what was observed.

So to be clear your answer to the question is a 'yes'?

It's a loaded question for a start. I gave you my answer...

"come up with a collapse sequence that aligns in more detail with what was observed."
Now there's an idea.

I note your inclusion of multiple simulation runs with parameter variation as a means to increase your confidence though. Interesting.

 

[femr2]

However it seems(one can never seem to tell what femr really thinks) that he expects local events to cause strictly local effects.

Not at all. Are you suggesting that the ~100 second motion in question, which in context was suggested to be due to mass redistribution, was explained by *steel is springy* ?

Hell of a long period. I wouldn't expect it to recover.

 

[jaydeehess]

In the context of this thread, analyse motion in video of WTC 1, 2 & 7.

No, that is what you propose to do. I am asking 'to what purpose?.

Enough work ? Irrelevant. Questionable results, sure.

How does one get 'questionable results if one does enough work?
You question the results you are questioning the work done to arrive at those results. are you now reduced to quibbling over semantics?

Incorrect. I have no immediate intention to *write a paper to be submitted to a peer-reviewed journal* or *contact NIST*. If you want to, go ahead.

You speaking to me? Did I suggest you write a peer review paper, I forget.
However what I asked you was if you thought there was something of significance to investigate and you answered, kind of, that there was not so i did a double take and asked you to clarify and now I get more irrellevent buzzing instead.......

It's a loaded question for a start. I gave you my answer...

"come up with a collapse sequence that aligns in more detail with what was observed."
Now there's an idea.

I asked you if it was a 'yes' and you simply re-iterate the previous reply that I asked clarification on.
got it.

I note your inclusion of multiple simulation runs with parameter variation as a means to increase your confidence though. Interesting.

ummmm, yessss, that is kinda how its done when done properly since its not possible to know exactly how the variation of those parameters will affect the outcome given the complexity and sheer number of calculations being done, nor is it known exactly what the initial conditions are.

the limitation on this is of course how much resources you are going to put into it and the determination of the value of the return for putting more into it.
that is pretty much my question to you over the last day or so.
What return of significant value are you getting from this exercise?

You didn't know that?

 

[jaydeehess]

Not at all. Are you suggesting that the ~100 second motion in question, which in context was suggested to be due to mass redistribution, was explained by *steel is springy* ?

Hell of a long period. I wouldn't expect it to recover.

Its inelegant but .yes.
Why not?

ETA: I should add that if it did not recover due to the springyness of the steel (in both vertical and horizontal) then what shoved it back? (and added sarcasm before I break off,,, was it a Judy Wood/ Hutchison tractor beam?)

 

[leftysergeant]

Its inelegant but .yes.
Why not?

I'm looking at it as an old hose-dragger, not a number-cruncher.

The fires travelled, the heat was not uniform in time or space. Expansion and contraction of steel structural members would, similarly, not be uniform or constant.

A cannonade of multi-ton steel projectiles piercing and walloping the building randomly also adds a bit of chaos to any equation you might want to apply here.

 

[W.D.Clinger]

Of course. See repost of the simple dialogue leading up to where you jumped in. Always useful to read threads in full. Context is kinda useful.

Not always. For a counterexample, read this thread.

I'm in no rush.

Agreed.

Quantity of posts, words and graphs does not constitute quality of arguement or even establish that there is a point to all of it.

Agreed. For an example, read this thread.

In femr2's defense, tfk started it. He's been stymied by femr2's mastery of the slow pitch, but keeps swinging. In some sports the number of swings is limited by rule, but that doesn't apply here at JREF. I'm not entirely sure what to make of it all; perhaps it has something to do with the IOC's decision to drop softball. I think I'm gonna stop reading and wait for the movie/YouTube version.

 

[femr2]

I think I'm gonna stop reading and wait for the movie/YouTube version.

It went fairly quiet on the thread until DGM, quite reasonably, commented upon the 100s period of motion prior to pre-existing published tomes data, which I think my response (stating at least 100s) was also fairly reasonable.

The ensuing nonsense seems to be on-par for the environment. They just can't seem to help themselves.

Perhaps you are right, and only data in YT form is *acceptable*.

I'll continue to post trace graphs here of course. If folk want to discuss them *like grown-ups*, that's fine.

I do think it's quite humerous that folk demand to know the outcome of an analysis before it's completion, and in the same breath dismiss the data because that analysis (which hasn't been completed) proves (insert their own personal viewpoint). Great stuff.

 

[femr2]

Not always. For a counterexample, read this thread.

In all fairness, huge swathes of this thread have been devoted to the utterly banal whinings of tfk et al, on such ridiculously simple topics as interlaced video terminology. I mean, jeebus.

Perhaps *the whole thread* is the wrong phrase, but the recent *confusion* about the priod of movement is just ridiculous. I reposted a complete lead-up trail, which consisted of about 5 one-liner comments within the last 20-odd comments, and yet was STILL recieving whining about being unclear about the topic in hand. Yawn.

Folk are just too lazy. If they have no interest that's fine, don't comment, but making half-arsed whining comments is just a waste of everyones time. The *quality* of the thread went out the window very early on with the constant pointless noise level.

Am I holding some nefarious *trump card* up my sleeve, waiting to sucker-punch someone with it for *falling into my trap* ? You'd think so by folks resistance to discuss, and the humerous demands and accusations kicking about.

The answer is no, it's ongoing research. Not interested ? Fine. Don't comment.

 

[DGM]

Expected ? What would you suggest as being the cause of the several minute period of ascillation ?

How would you suggest the NIST initiation conclusion correlates with that ?

Sorry I seemed to have missed this reply.

I can picture failures in the long span trusses linked to girders (and possibly the girders themselves) connecting columns 81,80,79 and 44 setting up movements in the building.

 

[femr2]

Sorry I seemed to have missed this reply.

No worries. Lots of noise.

I can picture failures in the long span trusses linked to girders (and possibly the girders themselves) connecting columns 81,80,79 and 44 setting up movements in the building.

Do you think the, pretty much full height, damage/failure of column 20 would allow flex of the facade without extensive internal failures ?



Would you discount wind ?

 

[carlitos]

You boney folk might enjoy this "humerous" video, featuring a word I love to see used here.

 

[DGM]

Do you think the, pretty much full height, damage/failure of column 20 would allow flex of the facade without extensive internal failures ?

It was an open floor plan building. Any exterior column (or truss/floor) failure could easily cause redistribution of loads distorting the exterior, (even if it's only temporary)

Would you discount wind ?

I can't discount anything. The winds were very light that day though.

The problem here is any number of a thousand things can cause what you've observed. I think it's most likely a "death shake" of a building that's quickly loosing it's battle with gravity.

 

[jaydeehess]

Perhaps *the whole thread* is the wrong phrase, but the recent *confusion* about the priod of movement is just ridiculous. I reposted a complete lead-up trail, which consisted of about 5 one-liner comments within the last 20-odd comments, and yet was STILL recieving whining about being unclear about the topic in hand. Yawn.

and given the fairly large number of graphs in this thread it just might, may be nice to reference back even if its only a few posts back the post number. Such as "the 60 to 160 second period show in the graph in post ###"

Just saying.

Folk are just too lazy.

Lazy? No, I had looked around and errorneously viewed a different graph that showed an oscillation of about 1/7 Hz which was , as far as I was concerned, fairly reasonable, and therefore commented.
It only became clearer after a few more posts. Sure I erred but you simply assumed that no one could not know exactly what you were referring to.

The answer is no, it's ongoing research. Not interested ? Fine. Don't comment.

Sure I understand ongoing research. I have commented though, that given the pretty demonstrable fact that even if one totally accepts your method all you have done is determine with more precision the movements of a 47 storey structure with major structural damage and ongoing major fires on several floors.

I see no reason to suspect that the structure will not move about in odd ways. I see no way to use this +/- inches movement to determine anything useful about what exactly is happening inside the building. As far as I am concerned I cannot envision you determining anything more detailed than what NIST did.

It seems you are trying to illustrate how closely the FEA did or did not precisely match the movement of the structure. The FEA was never, and in practical terms and usage , cannot ever perfectly match the observed and recorded collapse.
One could throw unlimited funds at the re-running of the FEA and perhaps come up with something closer but at some point your return on inverstment gets smaller and smaller.

Do you have a purpose to all of this? Would it be useful in some way to anyone if you could find that there was an internal failure even 4.5 minutes prior to the penthouse falling?


this thread is entitled 'discussion of femr's video data analysis' and you are seing such discussion. You have tfk questioning your method of arriving at resolution and several others, including me, questioning how a 'half height' video field could ever be considered a complete image.

If you did not want such discussion then perhaps you should have simply waited until you finished before even posting about it at all in the JREF forums. That horse has left the barn though.