Merged Applicability of Bazant's model to the real world

[GlennB]

Where the tactic fails is that when asked "OK, so let's suppose the NISTian view of collapse initiation is flawed. What are you proposing to take its place?" then the silence is deafening. Or the shiftiness of the obfuscation and goalpost-moving is dizzying. So let's try it ...

Detailed analysis of the actual behaviour and sequence of the actual events individually for all three buildings.

I have already presented much raw data for WTC 7 and WTC 1.

See my previous post.

Something real rather than imaginary. Detailed observation and measurements can be put together in a list. If your view of collapse initiation is contrary to the observables, it is just your imagination.

If your view of collapse initiation is consistent with observables, it is worth considering.

The NIST description is imaginary for the most part.

Bingo. You've proved my point so quickly it was almost funny.

 

[DGM]

The ROOSD explanation is not unique. It happens to be the mainstream accepted explanation of the 'global collapse'. Sure MT has added some details which may not be mainstream but as sure as the cloudless sky is blue the broad outline of 'ROOSD' is how the twin towers collapsed.

So if I understand the argument correctly, the issue with the Bazant model is with the size of the collapse front. The more the floor collapse leads, the less applicable it becomes?

 

[femr2]

So if I understand the argument correctly, the issue with the Bazant model is with the size of the collapse front.

The Bazant and co model(s) are fundamentally based upon the limiting case mode of destruction in energetics terms.

The actual descents did not match the model behaviour, and it is not expected that they should. Indeed, the opposite.

The size of the collapse front is irrelevant. The mode of destruction is the important factor. The actual descents did not involve any significant amount of core or perimeter column buckling, which is a base assumption of the model(s).

The more the floor collapse leads, the less applicable it becomes?

No.

 

[pgimeno]

But your humble servant, Major_Tom, put the best record together of the collective events to date to further our common knowledge of the collapses.

Where's that dog?

Ah, yes.

Once collapse initiation allows the top of the building to fall through one story, BZ claims the building is toast.

It leaves the initiation unanswered. Initiation is the natural place last hope for the demo believers to look for the difference between demo and natural collapse.

FTFY.

 

[W.D.Clinger]

First of all, I thank ozeco41 for responding to my posts.

...If (as femr2 may^* be arguing) the downward progression of floor failures outstripped the downward progression of perimeter and/or core failures,...

YES and it's not just femr2 who has that bit right. It is something which I thought was known and taken for granted as the mainstream understanding of the 'collapse progression'. What I have called 'global collapse' and described since 2008 as three parallel but staggered in time processes. Office space pancaking, ahead of and leaving the outer columns unbraced to fall later - not much later but definitely later - whilst the core failed mostly by strip down of the horizontal beams as indicated by the 'spires' which remained standing briefly after the main part of collapse was over.

Sorry to arrive late. You may find this hard to believe, but I have not been following your posts since 2008.

I don't think the highlighted phrase is terribly controversial. With respect to the applicability of Bažant et al's model(s), the important question would be their sensitivity to "not much later". Another question is the meaning of "not much".

... That could make it more difficult or impossible to apply the model(s) to the later portion of the collapse, when the lag was greatest,...

Not just the later part IMO but yes. That is why the Bazant model does not fit the real world. Recall that I accepted pgimeno's logic differentiating between 'fitting the parameters of WTC collapse to the model' AND 'fitting the model to the real world'.

Your highlighted statement puzzles me. Combining it with your following sentence, you appear to assume that even a small lag would prevent the Bažant model(s) from fitting the real world.

... although it might be possible to work around that problem by treating the frontier of floor failure as the lower crushing front...

I have suggested other ways of fitting the Bazant model to the realities of WTC but let me not diverge at this stage.

It's fine with me if you don't want to talk about it, but your use of the word "other" would seem to mean you have not suggested applying Bažant et al's model(s) in the manner I suggested. Combined with your "why the Bazant model does not fit the real world", I conclude that you think I'm missing something obvious here.

I don't know what you think I'm missing. I'm not saying you haven't explained it; I'm saying that, if you did, I missed it or didn't understand it.

...I don't think I've seen anyone make that argument, possibly because few people believe that floor failures could have gotten very far ahead of perimeter and core failures....

Isn't Internet communication a funny animal. That argument is the main premise underpinning most of my posts on this topic. I would have presumed that most people involved in discussing the topic would either have taken that argument as their starting point OR seen it in the various detailed posts I have made identifying the three separate but linked mechanisms involved in the global collapse.

Yes, Internet communication is a funny animal. That's why science and engineering communities use the Internet for informal discussions and for dissemination of results, but also have more formal processes in place for evaluating arguments that, in the opinion of their authors, deserve to be taken as the starting point for subsequent discussions.

...If floor failure led perimeter and core failure, but not by much, then Bažant et al's assumption of vertical homogeneity remained approximately true and their model(s) should remain approximately applicable (with appropriate parameters)....

Possibly but I have no interest in either defending or attacking Bazant. Merely in determining "Applicability of Bazant's model to the real world"

The possibility you admit here should prevent you from dismissing the applicability of Bažant et al's model(s) out of hand.


ETA: Would it help for me to respond to your post #1447? You might have misinterpreted silence, possibly motivated by deference to your experience, as agreement.

 

[pgimeno]

An important factor most seem unable to comprehend is that much of the detail and data I have released provides confirmable detail against many current *CD* theories.

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

The Bazant and co model(s) are fundamentally based upon the limiting case mode of destruction in energetics terms.

The actual descents did not match the model behaviour, and it is not expected that they should. Indeed, the opposite.

The size of the collapse front is irrelevant. The mode of destruction is the important factor. The actual descents did not involve any significant amount of core or perimeter column buckling, which is a base assumption of the model(s).

I've hilighted an important factor. Energetics terms. Good.

If you throw a ball in vacuum from 1 m in height, what will its final speed be just before hitting the ground?

And if you throw it through a ramp which has 60° inclination (considering friction neglectable)?

And if you throw it through a ramp which has 13.7° inclination?

And if you throw it through a toboggan which is shaped like the integral of sin(x)/x dx?

If your answer was not the same in all four cases, you're doing it wrong. The reason is that the starting potential energy determines the final kinetic energy, from which the speed can be extracted, without any need of calculating the intermediate speeds.

So, if the models are "fundamentally based upon the limiting case mode of destruction in energetics terms", 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.

 

[ProBonoShill]

Don't do it to yourself.

You are absolutely right.

It's a shame you don't understand why though.

As shown by these statements:

The calculated motion profile of the crush front is not the same as the actual motion profile.

You are highlighting a behavioural difference between the model and the real world.

ROFL. Do it ! I'm talking about actual motion in real video. Measure it yourself. It's not a belief, it's confirmable measurement.

And yes, it highlights a behavioural problem with the Bazant et al model(s), though you should take note of...

Second B of BLGB.

You too.

One last time femr, then I'm giving up, what you're measuring and what Bazant et al are referring to in their paper are two entirely different things.

If I dropped a brick from the top of a 100 story building, would it's descent rate be faster at floor 99 or the bottom floor?

Momentum is not a good topic to discuss with femr2...

Apparently not.

 

[femr2]

An important factor most seem unable to comprehend is that much of the detail and data I have released provides confirmable detail against many current *CD* theories.

OK, so you confirm that Bazant was right in his overall conclusion.

Need I remind you how many times I've stated that the Bazant et al model(s) provide reasonable proof that, given the suggested initial state, there was enough energy available for propogation to ground ? That is the only overall applicable conclusion.

That's about as far as they should have gone imo.

That you somehow confuse my statement, which relates to pre-release movement, with something you think was concluded in the Bazant papers is mind boggling.

How you could get from one statement to the other is similarly mind-boggling.

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.

What *match with reality* ? (Careful now)

I assume you have by now read the thread I pointed you to, which contains the trace data and discussion of the SW crush front ejecta traversal behaviour ? If not, go read it before you feign my position being based upon a couple of sentences.

Better still, go and trace the SW crush front yourself. It's not rocket science.

Try gathering some data from the actual event and comparing it to a limiting case model output.

Who feels like arguing with... If you get a match, you've not configured the model correctly

Have a nice day.

 

[TruthersLie]

Not my source. Not a doctored video.

The source posted by MT is a video by xenomorph who he lauds.

If you are going to use a video by someone who is known to have doctored vidoes on his channel, then you have a contaminated source.

It really is rather simple. Isn't it?

 

[femr2]

One last time femr, then I'm giving up, what you're measuring and what Bazant et al are referring to in their paper are two entirely different things.

No, they are not.

You are expecting the crush front to accelerate. Most folk generally do.

HOWEVER, if you actually trace the traversal of the crush front...it doesn't accelerate.

If you don't believe me, fine, no worries. Go and measure it yourself.

If I dropped a brick from the top of a 100 story building, would it's descent rate be faster at floor 99 or the bottom floor?

A trivial physics example does not change the facts of the actual event in the real world.

Exactly why the propogation rate remains pretty linear is a difficult one to answer, but I'd imagine that there is a rapid equilibrium formed between the resistance of each intact floors connections and some kind of self-regulating impacting debris volume/time effect. Possibly a limitation based upon surface area and compaction ratio. Not sure.

HOWEVER, the traversal rate of the crush front is NOT continually accelerating in the real world.

Have a nice day.

 

[ProBonoShill]

No, they are not.

You are expecting the crush front to accelerate. Most folk generally do.

HOWEVER, if you actually trace the traversal of the crush front...it doesn't accelerate.

If you don't believe me, fine, no worries. Go and measure it yourself.


A trivial physics example does not change the facts of the actual event in the real world.

Exactly why the propogation rate remains pretty linear is a difficult one to answer, but I'd imagine that there is a rapid equilibrium formed between the resistance of each intact floors connections and some kind of self-regulating impacting debris volume/time effect. Possibly a limitation based upon surface area and compaction ratio. Not sure.

HOWEVER, the traversal rate of the crush front is NOT continually accelerating in the real world.

Have a nice day.

Nevermind. Conversation with a brick wall is pointless.

Read pgimeno's last post, maybe you'll understand, probably not.

Have a nice day.

 

[femr2]

Nevermind. Conversation with a brick wall is pointless.

You are clearly not listening. Ignore away.

Read pgimeno's last post, maybe you'll understand, probably not.

Spherical cow.

Have a nice day.

You too.

 

[carlitos]

Most of tom's critical analysis is nonsense. Debunking my theory of a theory of apple freefall (or some such nonsense) ring any bells ?

If you still don't understand why calculating the terminal velocity of a hypothetical apple to 4 decimal places set tom off, I'm afraid that's your fault.

Why don't you input some parameters into the ROOSD model and see how it works in the real world?

 

[DGM]

It appears the objections here all boil down to different meanings of the word "model".

ROOSD model:

: a description or analogy used to help visualize something (as an atom) that cannot be directly observed

Bazant:

a system of postulates, data, and inferences presented as a mathematical description of an entity or state of affairs; also : a computer simulation based on such a system <climate models>

http://www.merriam-webster.com/dictionary/model?show=0&t=1296319528

Both are useful but, they are not comparable.

As far as real life observation, I'd go with ROOSD.



Just my $.02

 

[femr2]

If you still don't understand why calculating the terminal velocity of a hypothetical apple to 4 decimal places set tom off, I'm afraid that's your fault.

I know stating too many decimal places is a henious crime but that doesn't stop his responses being vitriolic nonsense.

Why don't you input some parameters into the ROOSD model and see how it works in the real world?

A functional (if you will) ROOSD model does not, as I'm sure you already know, exist. However, numerous pre-existing models have been modified and stripped down to include OOS floor slabs and their connections only.

Testing with a very simple asynchronous impact model resulted in...

It's smearogram-style.
Red vertical lines are seconds.
Blue tint is velocity.
Green tint is mass.
CR = 0.9
Failure = 73,000,000 J

Whilst that is NOT an implementation of the ROOSD model as such, it does show that the linear rate progression can be replicated easily. (Take note ProBonoShill)

 

[alienentity]

What are you proposing to take its place, for all 3 buildings?

Something real rather than imaginary. ...

The NIST description is imaginary for the most part.

ozeco, I rest my case.

 

[tfk]

oz,

You'll excuse me, but I think that you've got this "appeal to popularity" thing backwards.

I'll pull this statement out first.

Well the test of MT or femr's claims is "Are they correct?" NOT "How many people..[have you convinced].."

Absolutely 100% correct.

But you've got the wrong impression of me. I'm an old school, old fart engineer. Proudly crusty. I don't give a flying fig what the popular opinion is about anything.

My comment to MT was IN REPLY to his "… is tfk the last person here …" comment. Which IS exactly an appeal to popular opinion.

It's also the latest in a series of evade-the-question appeals to popular opinion that MT has issued, claiming that he has changed most people's opinions here regarding that validity of Bazant's various works.

There is a time tfk when you have dug yourself into a hole and it is time to cut your losses.

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

I started out with nothing more than a simple, completely reasonable request for them to explain their interpretation of the video that they posted.

Please provide your arguments / evidence that this is collapse progression & not pressure wave progression.

Please explain why, if this is collapse progression, there appears to be an un-collapsed corner of the building (vertical light streak = chamfered corner of the building) that remains standing for many floors after collapse wave has passed by.

Please show me the "appeal to popular opinion" in those questions.

Do you think that these questions are unreasonable?
Do they appeal to any authority?
Or are they directed at the observable physical events of the day?
No part of asking questions implies disagreement.

Wouldn't a simple, direct reply of the type, "well if it were a pressure wave, we'd expect to see this, but a collapse front would probably produce that" seem reasonable to you?

I was perfectly willing to listen to their answer.

But, you might notice if you review their posts since my question (in #1626), THEY NEVER OFFERED ONE.

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

In my experience, when people have reasonable explanations for things, they simply state them. When they don't, the hand-waving, mis-direction & theatrics begin.

I do not claim to comprehend the mindset of many posters here who have abuse of 'truthers' as their primary objective. Who will subordinate sound rational analysis of this matter of engineering forensic analysis to the need to insult those who hold differing views. So much so that, in this instance, you choose to deny well accepted explanations of WTC collapse events.

1. At what point in time did "asking 2 simple questions" become "abuse of truthers"?

2. "… sound rational analysis …"? WHAT sound rational analysis?

I asked two simple questions. Show me any attempt on their part to answer those questions in any manner. Much less with "sound, rational analysis".

3. "… well accepted explanations of WTC collapse events …" Did I just see an appeal to popular opinion go whizzing by?

I have said on several previous occasions if Major_Tom or anyone labelled 'truther' was to claim 'the cloudless sky is blue' he/they would be swamped by a pack of 'debunkers' claiming that the assertion about blue sky was wrong. The symptoms of denial would include personal attacks about qualifications; criticism that the claim about blue sky was not published in a peer reviewed journal article. All manner of evasions simply to avoid the fact that the 'truther' happened to be right.

I asked 2 questions, oz.

Not about femr or MT or their qualifications. Or the color of the sky.
About observable events of the collapse in the videos that they claim that they have analyzed in great detail.

And a question that is at the heart of one of their "best observations of the collapse ever" claims.

They wouldn't (& still haven't) answered.

The ROOSD explanation is not unique. It happens to be the mainstream accepted explanation of the 'global collapse'.

Man, you've gotta keep your head down. There are appeals to popular opinion flying all over the place around here.

Sure MT has added some details which may not be mainstream but as sure as the cloudless sky is blue the broad outline of 'ROOSD' is how the twin towers collapsed.

Permit me to point out a couple of things…

1. I've asked, about 4 times now where their ROOSD theory is posted. Who are its authors, etc. So that I could read a definitive version, when I get the time.

Femr's & MT's response: nothing.

I asked if it has been published anywhere. After all, the only postings that I saw are over a year old.

Femr's & MT's response: nothing.

3. Nobody, outside of the few posters at the 911 forum has the slightest clue what "ROOSD" stands for. Nobody of consequence in the structural engineering community has ever heard the term.

That doesn't mean that the "description" (what I have read thus far is not a "theory") is wrong. It DOES, however, mean that the description is unexamined. Unexamined by qualified experts. This is precisely why the "published in peer reviewed journal" system exists: to subject new ideas to the scrutiny of experts.

Anyone gets to ask questions & make observations. When it comes to providing credible answers, amateurs' opinions don't matter.

That is exactly why, if he is at all serious, MT should submit his description to JEM or some other tech journal.

And, even now at this late stage, you still want to continue with illogical claims. You ask "How many people do you think you've convinced that your ROOSD theory negates, invalidates, disproves NIST's analysis."

That was a question. Not a claim.

One possible answer from them might be (as you've suggested here) "ROOSD doesn't contradict NIST. It is pretty much the standard theory with a couple of embellishments."

Let's just say that I will be more than a little surprised if this is their reply..

I invite femr & MT to elaborate on this.

And anyone who has been around WTC collapse discussion should know that the extent of NIST analysis of the 'global collapse' was "global collapse was inevitable".

This is too simplistic, too facile. But this post is too long already.

I am well aware of the potential for Major_Tom, femr2 et al's explanations to lead towards CD. I have confronted each of the group - four of them - individually on the potential full scope of discussion. The potential for discussion to go towards MIHOP does not excuse invalid attacks on technical matters where they happen to be right. Otherwise we would all be obliged to denounce 'the cloudless sky is blue' as 'truther' dishonesty.

I am not prepared to go that far.

I didn't attack them. I asked 2 questions. That they haven't yet answered.
I didn't bring in CD or MIHOP, or LIHOP. You just did.

I asked 2 specific questions about distinguishing collapse front from the pressure wave.

And because I am an old fart, old school engineer, and have zero respect for people who simply JAQ off without basis or justification, I provided the EVIDENCE-based (not personality-based, or twoofer-based, or skeptic-based) reason for my question.

I don't believe, at the moment, that they have correctly identified the collapse front in that video. For the reasons that I stated. I could be wrong.

But we'll never know.

Because they won't reply to simple questions with direct answers.

As soon as someone (me, in this case) asks a simple question, instead of a simple direct answer, 2 bloody days of school-girl hysterics ensues.

This is THEIR theory. They brought it up for discussion. It is THEIR job to defend it when people ask questions.

If femr, or MT (or you) can't stand the minuscule heat of being asked a couple of simple question like this, if they can't provide even plausible (much less compelling) answers, then they damn well better not submit their paper to any group of real engineers.

They'll get eaten alive.

 

[alienentity]

If you get a match, you've not configured the model correctly

See Femr2, here's the thing: you haven't modeled the collapse, you've measured parts of it and are trying to form a hypothesis about what happened - but you don't have a testable set of math yet.

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. Even if it can demonstrate a mechanism for it.

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.

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.

But many of your leading assumptions are questionable as well; your notions of what the crush front is for example are prime examples, as many have pointed out.

 

[pgimeno]

Need I remind you how many times I've stated that the Bazant et al model(s) provide reasonable proof that, given the suggested initial state, there was enough energy available for propogation to ground ? That is the only overall applicable conclusion.

That's about as far as they should have gone imo.

That you somehow confuse my statement, which relates to pre-release movement, with something you think was concluded in the Bazant papers is mind boggling.

How you could get from one statement to the other is similarly mind-boggling.

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?​

What *match with reality* ? (Careful now)

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. Therefore

[since] the models are "fundamentally based upon the limiting case mode of destruction in energetics terms", 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.​

I assume you have by now read the thread I pointed you to, which contains the trace data and discussion of the SW crush front ejecta traversal behaviour ? If not, go read it before you feign my position being based upon a couple of sentences.

No, thanks. If you want, you can put it here where it can be read by other knowledgeable people who can evaluate its merit and after which I can form my own opinion. I prefer to not form myself an opinion on subjects that I'm not fully able to evaluate. 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".

That is, assuming I care enough to consider it, which I don't. The conclusion matches that of Bazant et al that the collapse propAgation did not involve a demolition with explosives. We already had it. Here's my former sentence yet again:

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

Better still, go and trace the SW crush front yourself. It's not rocket science.

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

 

[carlitos]

I know stating too many decimal places is a henious crime but that doesn't stop his responses being vitriolic nonsense.

It's not a heinous crime, it's just sloppy. And, as tfk noted, it shows that you don't seem to understand error analysis.

You have repeatedly shown higher precision than is possible in your analysis. tfk keeps reminding you of this, and you keep doing it. Even with regards to a hypothetical apple of unknown roundness in variable wind, you calculated velocity to 4 significant digits.* Why not incorporate the free lesson you got here at JREF in your future calculations, rather than focusing on tfk's drama?


*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.