Merged Applicability of Bazant's model to the real world

[femr2]

You'll excuse me if I disagree that asking a couple of questions about their interpretation constitutes "digging myself into a hole".

You know full well that is not the reason for the statement Tom. Try and recall the ever-increasing stack of...
's

ozeco41, tfk is very prone to adjusting the scope of his statements at a latter date in the futile hope of appearing all *hard done-by*. I tend to track back through discussions quoting the full to-and-fro to ansure the context is kept accurate.


Here, tfk, have you forgotten a couple of responses ? ...

http://www.internationalskeptics.com/forums/showpost.php?p=6819759&postcount=1707
http://www.internationalskeptics.com/forums/showpost.php?p=6816588&postcount=1639

No reply to the questions. But lots of personal snark.

ROFL.

I snipped out your angelic harp-playing BS.

I'll reconstruct the entire recent discussion if you feel like harping-on

Have a nice day.

 

[femr2]

Compare to the NIST WTC 7 model; it attempts to model the most relevant mechanisms which could lead to collapse. But even such a sophisticated model does not and cannot recreate every actual detail of the real collapse.

Of course. I'm responding to...

you will need more than handwaving or putting together a couple sentences in order to claim that the match with reality they obtained out of their model was by chance.

Highlighting that a match between real-world metrics (such as descent time, which is pretty much what is on the table here) and the calculated descent time for an entirely different mode of destruction and what should really be the maximum descent time possible...

...is pretty good indication of a badly configured model, imo

So your requirement is really a call to perfection fallacy - only you're applying in one direction - to NIST and Bazant et al., but not to yourself.

Not at all. Be specific.

If you were to simply state 'We don't actually know how collapse initiated' and then worked on some models to support various alternatives, I don't think anybody here would have a problem. But you two seem to think you 'know' exactly what happened, and that everyone else is totally wrong.

Please quote where I have stated a specific initiation sequence and mechanism.

Stating what it is NOT is far from the same thing.

Have a nice day.

 

[alienentity]

That assumes that it's a crush front. I no longer assume that.

Exactly.

 

[femr2]

I have also stated numerous times how I believe, according to my interpretation, that the conclusions of BLGB are that they disprove, as you put it, "many current *CD* theories", which is what you claim to be doing. Thus my statement:

OK, so you confirm that Bazant was right in his overall conclusion. Did we really need your confirmation?​

That is not Bazant's overall conclusion, it's yours.

BLGB figure 7 p.902 (11 in PDF). I don't even need to look it up again, because of the many times I've mentioned it already. You dismissed it saying that it was just luck that they matched. I don't buy that, that's a poor and cheap denial with no proof.

Limiting case would be the maximum descent time possible I rekn.

Actual core and perimeter descent time was MUCH longer than the OOS progression.

The Bazant time *matches* the OOS collapse time.

A match ? Nonsense.

I should indeed have known better before buying the hypothesis of the advanced outer flooring pancaking, which now needs to me a higher standard for proof than just "look at this video and you will see the floors pancake".

Wow. Multiple JREF regulars looking to debunk tha pancake theory, and the only theory of progressive collapse remaining for WTC 1 & 2.

Outstanding

 

[femr2]

to be fair, you found an online calculator and plugged in values, rather than doing the math yourself, but that's yet another of tfk's objections.

It's a quick estimate of the amount of time an apple would take to fall from the roof. tfk can object to whatever he likes. And probably will. Making a big fuss about the precision of a value is hilarious, and I suggest he hits the beach, cracks open a few bottles and invites some babes over

Have a nice day.

 

[carlitos]

Limiting case would be the maximum descent time possible I rekn.

I think you reckon wrong. The limiting case applies to the column-on-column impact at the start of the collapse, as the limit is 'conditions most favorable to collapse arrest' or something like that. How would that apply to the timing of the rest of the collapse?

ETA - Again, if you don't understand why four significant digits can't possibly be "a quick estimate" you just seem to be trying to prove how little you understand about math, physics or engineering. If this is your intent, go right ahead.

 

[alienentity]

...is pretty good indication of a badly configured model, imo

You're responding to a comment I didn't make. But in return for pointing out that simple error, perhaps I have conflated your views with M_T's, but I seem to recall you endorsing the antenna/core failure initiation hypothesis.

Perhaps I'm wrong and you don't endorse M_T's views. Please clarify if you can.

Stating what it is NOT is far from the same thing.

Indeed. You have no model to offer as an alternative. When will this be presented?

 

[femr2]

I think you reckon wrong. The limiting case applies to the column-on-column impact at the start of the collapse, as the limit is 'conditions most favorable to collapse arrest' or something like that. How would that apply to the timing of the rest of the collapse?

Exactly the same for each storey, by definition.

ETA - Again, if you don't understand why four significant digits can't possibly be "a quick estimate"

Oh, nonsense. Quick estimate as-in grab calculator, stuff values, paste timing.

you just seem to be trying to prove how little you understand about math, physics or engineering.

A very feeble and stupid *personal attack*. Funny stuff

Have a nice day.

 

[femr2]

I seem to recall you endorsing the antenna/core failure initiation hypothesis.

Endorse ? Your use of linguistic bias is interesting

I'm for core-led rather than perimeter-led, sure, however, that's not a specific sequence and mechanism. Far from it.

You have no model to offer as an alternative. When will this be presented?

ROFL.

Have a nice day.

 

[pgimeno]

Highlighting that a match between real-world metrics (such as descent time, which is pretty much what is on the table here) and the calculated descent time for an entirely different mode of destruction and what should really be the maximum descent time possible...

...is pretty good indication of a badly configured model, imo

Wow. Multiple JREF regulars looking to debunk tha pancake theory, and the only theory of progressive collapse remaining for WTC 1 & 2.

That's a dishonest misrepresentation of what's happening. Nobody here is "looking to debunk tha [sic] pancake theory". What is under question (note how "under question" ≠ "looking to debunk") is that there was a pancaking collapse front in advance.

 

[femr2]

What is under question (note how "under question" ≠ "looking to debunk") is that there was a pancaking collapse front in advance.

In advance of what ? Perimeter peeling ?

Are you serious ?

You're aware of why the perimeter peeling is termed as such ?

 

[alienentity]

I see - the model being offered is the ROFL model. It is quickly replacing ROOSD as the preferred acronym.

I wonder if there is any math to back it up.....probably not.

 

[beachnut]

... ...

...is pretty good indication of a badly configured model, imo
... Please quote where I have stated a specific initiation sequence and mechanism.

Stating what it is NOT is far from the same thing.

Have a nice day.

You will not state much of anything, your CD theory failed. I now watch truthers study a collapse for no reason, no goal, no purpose, and no conclusion. Where is your math to go with your model, which you have no clue you modeled, as you model it. The math with your 28 m/s visual stuff. The terminal velocity stuff? Don't to the cute little, you failed to read stuff, there is no need to read your nonsense, it has no goal, no intended outcome as you clearly indicate.

As for credit for the discovery of perimeter peeling....
collapses.

Oh, wow, you discovered perimeter peeling, gee whiz, you could have asked Robertson on 911 why the perimeter peeled, or studied the WTC tower. But you spend 9+ delusional years trying to prove CD, and you fail.

Why would a shell of a building, a shell which is responsible for the lateral strength of the WTC tower have a tendency to peel from the floors, which are attached to the core and shell. We have a core, not able to stand by itself, connected to a shell by a system of floors. Gee, how could the perimeter peel? OMG, you guys have broken the big story, your narrow observation on the WTC point to failure due to damage and fires. Darn, if you can connect the dots your CD theory can be dropped and you can join reality! Good job; what will you study next, the dust? Wait till you find there are systems engineers; OMG, your want to play engineer, will expand.

What makes that perimeter so darn strong, hurricane proof!? Still standing but looks like the floors peeled away too; is it a mutual effect, floors peeled off too, or broke off, or something? Looks like CD is getting harder and harder to dig up evidence.

Here is proof of floor and shell peeling, like eating an apple, the core is left. The apple core effect; who discovered this? Holy shell peel, another clue... Wow, we are on to something now; Bazant! Hold your horses! NEW STUFF!!!

Peeling perimeter, discovered on 911. The same day CD was ruled out.

Bazant was right, you were wrong. You are stuck on 911, the world has moved on.

 

[pgimeno]

In advance of what ? Perimeter peeling ?

Of the falling rubble layer.

 

[carlitos]

Exactly the same for each storey, by definition.

Could one of you engineers vouch for this please? Does Bazant's limiting case not only assume an initial column-on-column impact, but also direct, axial column-on-column impact for every single stor(e)y? I'd like to know. No offense to femr, but I would like a second opinion. The reports are beyond me.

Oh, nonsense. Quick estimate as-in grab calculator, stuff values, paste timing.

But that's not what you did. You made a video on the subject. From your video, we can see the precision with which you measured things. You calculated the density of the apple to 2 decimal places, the radius to the hundredths of a centimeter, mass to the ten-thousandths of a gram, and ended up with terminal velocity to 4 significant digits. I can only marvel at the precise scales and measurement devices you must have a casa de femr.

Screencaps from femrs "quick estimate" 53 second youtube video:

(ETA - I like how you left the calculations screened-back in the background. This reinforces my impressions of your motivations, but stylistically it's a nice touch)


So, if I may press tfk's actual point as I interpret it, why all the claimed precision about something as mundane as dropping an apple? If it's not technobabble designed to fool the credulous, what is it? Ditto Major_Tom's formula errors, which I don't believe he has corrected yet (I could be wrong - tedious thread is tedious).

My claim wasn't intended to be a personal attack. Your claimed precision seems to be, well, wrong. I've had math and physics teachers that would have dinged me for such things, as had tfk. Do you disagree? Did you measure a perfectly spherical apple with a micrometer that had precision to hundredths of a centimeter? What, exactly is the purpose for your claimed precision on these things?

 

[Major_Tom]

Beachnut, you misrepresented my quote and then totally supported the ROOSD concept.

Could you explain it to TFK? He is the last poster to not see what you've described.


Do you know that Bazant is the one with the crush down, then crush up model, yes? Do those pictures you posted demonstrate the principle of crush down, then crush up?

Think about what you are saying and thanks for promoting images from my website, while further backing the OOS collapse model. Your support is appreciated.

 

[beachnut]

Beachnut, you misrepresented my quote and then totally supported the ROOSD concept.

Could you explain it to TFK? He is the last poster to not see what you've described.


Do you know that Bazant is the one with the crush down, then crush up model, yes? Do those pictures you posted demonstrate the principle of crush down, then crush up?

Think about what you are saying and thanks for promoting images from my website, while further backing the OOS collapse model. Your support is appreciated.

Can you move on and stop the CD delusion? No.

Bazant was right, you are wrong. Next. Publish your study of a river running, and get on with it. 911 truth was covered in first grade. You guys are like the blind men and the elephant. We learned to spot your fraud, the fraud of 911 truth in grade school. Go ahead turn this around to support your fraud. It is what you do. The sun came up on 911, proof of CD. The wind was blowing, proof of CD. The smoke was black proof of CD. The smoke was white, proof of CD. Gee, whiz, now the perimeter peels, proof of CD. The funny part, you are too afraid to ask the girl to dance!.

You can't figure out how Bazant rules out CD. It is comedy. I observed the collapse of the WTC on 911, and figured out impact, fire, gravity collapse. What is your conclusion after 9+ years?

Are you upset? You think Bazant is wrong, but he got the big picture right, no CD. You spend years spinning your wheels and you can't present any backed up conclusion. Bazant's no CD claim is backed by evidence, your no claim, no goal, no purpose whatever it is, backed by nonsense.

 

[W.D.Clinger]

Exactly the same for each storey, by definition.

Could one of you engineers vouch for this please? Does Bazant's limiting case not only assume an initial column-on-column impact, but also direct, axial column-on-column impact for every single stor(e)y? I'd like to know. No offense to femr, but I would like a second opinion. The reports are beyond me.

I'm not an engineer, but I can answer that. By "Bazant's limiting case", you probably mean Bažant and Zhou 2002:

For our purpose, we may assume that all the impact forces go into the columns and are distributed among them equally. Unlikely though such a distribution may be, it is nevertheless the most optimistic hypothesis to make because the resistance of the building to the impact is, for such a distribution, the highest.

You should note, however, that Bažant and Zhou 2002 considers only the first impact, treating the entire lower section as a single unit. Their calculations show that some failure must occur within that lower section, from which an inductive argument would suffice to show that some kind of progressive collapse would follow, but Bažant and Zhou 2002 makes no attempt to model anything beyond that first impact.

That implies, of course, that any assumptions made in Bažant and Zhou 2002 are irrelevant to "the timing of the rest of the collapse". If someone tries to tell you otherwise, you can mark them down as an unreliable source.

(ETA: Let me qualify that. One paragraph of BZ contains a back-of-the-envelope calculation for collapse duration, but that calculation is superseded by later observations and papers (not just Bažant's), and I wouldn't trust that paragraph's conclusions. For present purposes, the interesting thing about that paragraph is that BZ's optimistic assumption of column-on-column impact makes the collapse faster, not slower, which may run counter to naive intuition.)

(ETA 2: And from your post #1766, I see it ran counter to femr2's intuition reckoning.)

Bažant's subsequent papers and a closure, popularly known here as BV, BL, and BLGB (in chronological order), attempt to model the rest of the collapse by generalizing and extending the BZ model. The generalized and extended model is described in BV, defended against criticism by the closure known as BL, and refined further in BLGB. One of the generalizations made in BV (and continued in the subsequent BL and BLGB) is that BZ's optimistic assumption is no longer necessary. The BZ model remains a special case of the BV model, but the BV model can be applied even without that optimistic assumption.

Because the BV model attempts to describe the rest of the collapse, you could use it to discuss the timing. BLGB actually does that. I don't have the journal version of BLGB, but I have two different preprints, both designated as Structural Engineering Report No. 07-05/C605c. In the version dated 15 December 2007, the model's timing is compared with the seismic record in Figure 7; in the version dated 31 March 2008, that comparison is in Figure 8. That figure, however labelled, shows agreement for both towers to within the seismic and calculation errors.

That argues in favor of the model's applicability. Those who are arguing against the model's applicability tend to dismiss that result on various grounds, but I don't understand their objections well enough to summarize them.

 

[Major_Tom]

Can you move on and stop the CD delusion? No.

Bazant was right, you are wrong.

I'm the one with the OOS collapse propagation model, He's the one with the crush down, then crush up model in which significant early crush up is proven to be impossible.

You can't figure out how Bazant rules out CD.

He doesn't. Frank Greening, one of the authors of BLGB, agrees.

 

[Major_Tom]

I'm not an engineer, but I can answer that. By "Bazant's limiting case", you probably mean Bažant and Zhou 2002:

You should note, however, that Bažant and Zhou 2002 considers only the first impact, treating the entire lower section as a single unit. Their calculations show that some failure must occur within that lower section, from which an inductive argument would suffice to show that some kind of progressive collapse would follow, but Bažant and Zhou 2002 makes no attempt to model anything beyond that first impact.

Correct, a cartoon extreme case of a single collision.

Correct, no attempt to derive real roof-line movement in BZ.

That implies, of course, that any assumptions made in Bažant and Zhou 2002 are irrelevant to "the timing of the rest of the collapse". If someone tries to tell you otherwise, you can mark them down as an unreliable source.

Exactly. Please explain this difference to Myriad.

Bažant's subsequent papers and a closure, popularly known here as BV, BL, and BLGB (in chronological order), attempt to model the rest of the collapse by generalizing and extending the BZ model. The generalized and extended model is described in BV, defended against criticism by the closure known as BL, and refined further in BLGB. One of the generalizations made in BV (and continued in the subsequent BL and BLGB) is that BZ's optimistic assumption is no longer necessary. The BZ model remains a special case of the BV model, but the BV model can be applied even without that optimistic assumption.

The intention is to map the movement of real buildings in the case of 4 simplifying assumptions. The aim of the paper was to derive eqs of motion that can be fitted to real buildings.

So I agree, except for the word "can" in the last sentence. I'd replace it with "should". BV is trying to predict and match movement of real buildings.

Because the BV model attempts to describe the rest of the collapse, you could use it to discuss the timing. BLGB actually does that. I don't have the journal version of BLGB, but I have two different preprints, both designated as Structural Engineering Report No. 07-05/C605c. In the version dated 15 December 2007, the model's timing is compared with the seismic record in Figure 7; in the version dated 31 March 2008, that comparison is in Figure 8. That figure, however labelled, shows agreement for both towers to within the seismic and calculation errors.

I agree. Correct.

That argues in favor of the model's applicability. Those who are arguing against the model's applicability tend to dismiss that result on various grounds, but I don't understand their objections well enough to summarize them.

This is not true, but you have given the best summary outside of Ozeco from the debunker camp on this forum.

David Benson and poster OneWhiteEye of the 9/11 forum have studied that last point in detail over a couple of years.

It is important to realize that data is extracted from WTC1 using roof-line measurements and antenna measurements. If buffer system "zone B" does not effectively separate the top "block" from the lower "block" as Bazant describes, then his assumptions about roofline movement in his equations have no meaning.

His equations over the first 3 seconds of motion are totally reliant on "zone B" shielding the "upper block" from the "lower block". Great idea in 1-D. But in a world where columns can spear floor slabs and the two "blocks" can penetrate one another through column spearing and perimeter sheets can bypass one another, the predictions of roofline measurement from his equations have no meaning.


Leaving one last question: How did Dr Bazant get his equations to match data for the first 3 seconds of motion and seismic records? We were asking the same question 2 years ago.