Merged Applicability of Bazant's model to the real world

[femr2]

I could perhaps agree

Perhaps ?

Have you looked at upper block perimeter behaviour ?

but that doesn't prove in itself that the (necessarily) simplified mathematical model can't be applied to the real scenario

The visual record shows the upper block did not remain intact.

even assuming FEMA's pancake collapse of the exterior flooring as right.

FEMA's mechanism description is fatally flawed.
The ROOSD study addresses the appropriate scope, which I think you agree with, yes ?

If you don't agree with either, what is your proposed primary descent mechanism ?

I opened this thread to discuss whether it can be applied or not to the real world

However, the mods, for bizarre reasons, have merged MT's wider scope BZ refutement thread with yours, so I suggest you request they un-merge it, as that decision has messed with the thread boundaries considerably.

however, some people are just assuming and stating it can't, without proof or discussion

Oh come on. It's an idealised simplified model. There's justification in favouring upper block survival in a purely 1D simplified form, but add full axis movement, thousands of separate individual property members...and the assumption doesn't apply.

Regardless, the evidence is clear, again, upper block perimeter peeling being one of several observable features.

So, who are these people assuming without proof or discussion ?

and blame the author of the model as if he was hallucinating.

The upper block did not remain intact. Proof is clear.

Assuming it did is just stupid. Highlighting that the authors are suggesting that behaviour applies to the real world is sensible. Others arguing here that it does in fact apply to the real world is just nonsense.

The upper block did not remain intact.

Expecting it to is more bizarre than expecting it not to imo.

Remember, the model has no inclusion of any individual element strength.

Remember how many folk roun'these'parts emphasise how important it is to include the fact that tilt ocurred, OOS connections are a weak link, core columns did not buckle but broke at splices, ...in order to understand how the thing came down.

You know these things, but seem to be arguing the toss due to the model math not being included in the argument here.

The 1D mechanics apply okay in a 1D sense. Reality is a different kettle of fish.

Anyone, Bazant, you, whomever...suggesting that crush-down-only followed by crush-up-only ocurred in the real events... is wrong.

 

[Myriad]

The last I recall discussing the Bazant model(s) with Major_Tom, he was insisting that the models in the later papers (especially BV) did not embody the same best-case-favoring-collapse-arrest assumptions as in BZ. That seems to be the basis for Major_Tom's claim of "different models." I was showing him exactly where and how they actually did. To my knowledge, he never responded to my last post 254 on that aspect of the topic, so as far as I am concerned those issues are resolved, with my post 163 best expressing my basic views on the matter.

Respectfully,
Myriad

 

[Major_Tom]

Dave, you are either aware that you are feeding untrue statements to your fellow posters or you are not.

You have been feeding untrue statements to other posters since I started the OOS thread in May.

There is no doubt about it since you now appear and start doing the same thing again.


There is not doubt that you have no clue what you are taking about.

Try really reading the papers. maybe for the first time.

 

[Major_Tom]

Myiad, you were possibly the single worst violator of merging BZ and BV.

I'll refresh your memory on the OOS thread later today.

I know you are spreading lies on this forum. The only question is whether it is intentional or unintentional.

 

[Myriad]

Myiad, you were possibly the single worst violator of merging BZ and BV.

You keep asserting this, but you have presented no rationale, let alone evidence, for that assertion.

Show me where any of the assumptions favorable to collapse arrest made in BZ are modified or removed in BV (other than in the parametric study in which a wide range of assumptions is tested -- and even there, buckling of all columns is still asserted for the case labeled as most applicable to the WTC towers).

Respectfully,
Myriad

 

[tfk]

A simple set of questions were asked...


Tom, do you believe in the concept of crush down, then crush up?

Please explain to us little people why Bazant is correct when he claims that significant crush up is impossible before crush down is complete.

Is he wrong? Why or why not?


Nice simple answers please.

So let's end this charade.

By virtue of his bombastic, blow hard claims to be able to "walk thru" Bazant's errors for anyone, and his assertion that Bazant's BZ model are is different & distinct from his later ones ...

... but when invited - REPEATEDLY - to back up his bluster with action, Major_Tom clams up & passes the buck.

There is absolutely no surprise to this.

When asked rudimentary questions, his wrong answers prove beyond doubt that he understands almost nothing about the real engineering considerations, and absolutely none of the math behind it.

His silence proves that he is not particularly bright. He seems to expect that his "bluff & fold" act will not be patently obvious to everyone.

He can do no more than cut & paste, & parrot the writings of others.

The beginning & end of his original contribution is 1) baseless assertion & 2) argument from incredulity.

In other words, he's a blustering braggard & a fraud.

Quel surpris, there…

I can WELL understand, femr, why you find his competence & epistemology so, uh, familiar & compelling.
___

And now, with trollish repetition of answered questions - which you seem to think wins some point or other - you've demonstrated the (5th grade?) level of argument that you find "useful".

I will answer these question when I have the time. I'm doing approximately 80 hours/week now, and truther delusions of adequacy are far from a priority.

 

[femr2]

So let's end this charade.

Simple questions Tom, simple answers.

By virtue of his...

Talk to MT if he's on your mind.

I will answer these question when I have the time.

Rather than the pointless and rude rant above, you would have saved time simply by answering...

Tom, do you believe in the concept of crush down, then crush up?

Please explain ... why Bazant is correct when he claims that significant crush up is impossible before crush down is complete.

Is he wrong? Why or why not?

 

[tsig]

Simple questions Tom, simple answers.


Talk to MT if he's on your mind.


Rather than the pointless and rude rant above, you would have saved time simply by answering...

Tom, do you believe in the concept of crush down, then crush up?

Please explain ... why Bazant is correct when he claims that significant crush up is impossible before crush down is complete.
Is he wrong? Why or why not?

Could you cite the part of the report that says that?

 

[pgimeno]

but that doesn't prove in itself that the (necessarily) simplified mathematical model can't be applied to the real scenario

The visual record shows the upper block did not remain intact.

That's because the model is an approximation, but that still does not make the model inapplicable. No matter how many times you repeat that it did not happen, you are not addressing my point. Please read the OP again. Here's an excerpt to let you know why I'm insisting:

The corollary is that it is possible to draw some conclusions even from an inexact model, just not any conclusions, and we have to be careful about which ones can be extracted and which ones won't match the real world to any sufficient degree of accuracy at all.​

So, instead of arguing what happened and what didn't happen, the focus of the thread should be what conclusions can be extracted and what can't.

Your repeated statement boils down to the assertion (which, again, I can agree with) that one of the things that the model doesn't predict accurately is the crush direction. OK, fine. But that doesn't make the model inapplicable in itself, and that's what you and MT seem to be confusing all the time, and what is fueling MT's shameful smearing campaign.

Off topic:

FEMA's mechanism description is fatally flawed.

http://www.internationalskeptics.com/forums/showthread.php?postid=6133238#post6133238

(see message #761 and #763). That's not my understanding of what "fatally flawed" means if we're talking about pancake collapse progression.

 

[femr2]

Could you cite the part of the report that says that?

Sure...
http://the911forum.freeforums.org/review-of-bazant-and-le-t453.html#p14143
...
http://www.internationalskeptics.com/forums/showpost.php?p=6773683&postcount=1289

 

[femr2]

That's because the model is an approximation, but that still does not make the model inapplicable. No matter how many times you repeat that it did not happen, you are not addressing my point.

...and the mods have merged a thread with wider scope, and until it's split back out I'm afraid the scope of this thread has widened.

See the links above for additional info.

Please read the OP again.

You know I've read it.

So, instead of arguing what happened and what didn't happen, the focus of the thread should be what conclusions can be extracted and what can't.

Again, I'm afraid the mods have mashed your thread scope.
This thread now contains another with one of it's primary features being the refutement of the Bazant et al repeated application of crush-down before crush-up, which is clearly false.

Your repeated statement boils down to the assertion (which, again, I can agree with) that one of the things that the model doesn't predict accurately is the crush direction. OK, fine.

Fine, and I understand your frustration with having the mods effectively hijack your thread scope. I suggest you, as thread start, request they unsplit from MT's OP here...
http://www.internationalskeptics.com/forums/showpost.php?p=6773683&postcount=1289

But that doesn't make the model inapplicable in itself

I never said such. I've made my view of the applicability of the model clear within the thread previously on several occasions.

and that's what you and MT seem to be confusing all the time

No. Again, I've made my view of the general scope of applicability repeatedly clear, and current discussion is about the validity of the Bazant et al statements about crush direction.

 

[pgimeno]

No. Again, I've made my view of the general scope of applicability repeatedly clear, and current discussion is about the validity of the Bazant et al statements about crush direction.

No, it is not. Your current discussion (and MT's) is to confuse Bazant's description of the behavior of his model with the behavior of the real towers with respect to an aspect that the model does not predict (which is thus irrelevant), making a straw man attack out of it by claiming that the paper is flawed.

 

[femr2]

No, it is not. Your current discussion (and MT's) is to confuse Bazant's description of the behavior of his model with the behavior of the real towers with respect to an aspect that the model does not predict (which is thus irrelevant), making a straw man attack out of it by claiming that the paper is flawed.

Nonsense.

Here's one of the many quotes in the links I pointed you to...

The crush-up simultaneous with the crush down is found to have advanced into the overlying story by only 37 mm for the North Tower and 26 mm for the South Tower.

Here's a pretty comprehensive list of crush direction references, again...

http://the911forum.freeforums.org/viewtopic.php?f=17&t=453

As I've said previously...

The 1D mechanics apply okay in a 1D sense. Reality is a different kettle of fish.

Anyone, Bazant, you, whomever...suggesting that crush-down-only followed by crush-up-only ocurred in the real events... is wrong.

I'm not confused in the slightest.

Again, as previously stated numerous times...I'm fine with the basic conclusion of the limiting case mathematical 1D model, given the simplified initial conditions, that there is enough energy available for propogation to ground.

 

[Major_Tom]

TFK: "By virtue of his bombastic, blow hard claims to be able to "walk thru" Bazant's errors for anyone, and his assertion that Bazant's BZ model are is different & distinct from his later ones ..."

BV derives equations of motion to be applied to actual progressive collapse.

BZ presents a single collision extreme (cartoon) case in which after a 12 ft drop, all columns collide axially. Nobody expects the collision in BZ to ever happen in reality.

Can you see the difference? BZ is an extreme case of one single collision. No intention to map a real event.


BV derives actual eqs of motion to track the movement of real buildings. BL applies the BV eqs of motion to WTC1, as does BLGB.


I have no idea how anyone can confuse the two. Yet almost no regular JREF poster can distinguish them without help from this twoofer.


Ozeco, can you see what I have dealt with since last May? Ozeco, how do you explain the extreme fog in which many of these people reason? Can't you see something is wrong here?


Ozeco, how can you explain such incredibly poor abilities on the part of your fellow posters?


Does everyone know what eqs of motion are? They track objects in space and time.

There is no intention to track real objects in BZ.

That is the whole purpose of BV. See the difference?

 

[pgimeno]

Let me put an example. Change the towers' collapse by an apple thrown from the top of a building, of which there's a video record that shows that in that windy day, the apple deviated substantially from the vertical.

Now Bazant writes a paper that describes the effect of gravity over the apple, using a simplified model that doesn't incorporate the (highly chaotic) effects of wind, just Newton's laws, and that therefore predicts that the apple falls straight down, and gives a decent approximation to the speed of the fall.

Now, BL boils down to James Gourley saying: "The apple can't fall straight down because Newton's Third Law predicts that there's a force opposing gravity that can act in any direction." That is, totally misrepresenting the model and the laws of physics. That's what he did.

And Bazant responding: "That's wrong, according to my model it must fall straight down no matter what."

And now you and MT are saying: "The apple deviated from the vertical substantially, it's in the videos, therefore Bazant's model is fatally flawed. He claims that the apple fell straight down, which is not what we saw at all."

Well, that's irrelevant. A known limitation of the model is that it doesn't incorporate the effects of wind, yet that doesn't diminish its validity nor its applicability.

I've made it intuitive in this case that this model CAN predict things like the speed of fall to a certain degree of accuracy. That could be a subject of discussion in the case of Bazant's papers. I believe that's something Ozeco and I agreed.

 

[Major_Tom]

Incorrect as usual.

Consider this passage from BL:

"4. Can Crush-Up Proceed Simultaneously with Crush
Down? It can, but only briefly at the beginning of collapse,
as mentioned in the paper.
Statements such as “the columns supporting the lower floors
. . . were thicker, sturdier, and more massive,”
although true, do not support the conclusion
that “the upper floors ͑i.e., the floors comprising Part C͒
would be more likely than the lower floors to deform and
yield during collapse” ͑deform they could, of course, but
only a little, i.e., elastically͒.

More-detailed calculations than those
included in their paper were made by Bažant and
Verdure to address this question. On the basis of a simple
estimate of energy corresponding to the area between the
load-deflection curve of columns and the gravity force for
crush down or crush up, it was concluded at the onset that the
latter area is much larger, making crush-up impossible."


His words, not mine.

Would you like to see Bazant's proof as to why crush up is impossible? He has a few of them.

Do you believe that crush up is impossible before complete crush down just because the good Dr says so? If you do, you are pretty gullible.


Should I show you how many times Bazant insists the same thing?

 

[femr2]

Let me put an example. Change the towers' collapse by an apple thrown from the top of a building, of which there's a video record that shows that in that windy day, the apple deviated substantially from the vertical.

Now Bazant writes a paper that describes the effect of gravity over the apple, using a simplified model that doesn't incorporate the (highly chaotic) effects of wind, just Newton's laws, and that therefore predicts that the apple falls straight down, and gives a decent approximation to the speed of the fall.

Nonsense.

Apple from the top of WTC1...

With *wind* (air resistance) ~17.5s

 

[Dave Rogers]

Apple from the top of WTC1...

With *wind* (air resistance) ~17.5s

Please show your working.

Dave

 

[pgimeno]

Incorrect as usual.

Consider this passage from BL:

"4. Can Crush-Up Proceed Simultaneously with Crush
Down? It can, but only briefly at the beginning of collapse,
as mentioned in the paper.
Statements such as “the columns supporting the lower floors
. . . were thicker, sturdier, and more massive,”
although true, do not support the conclusion
that “the upper floors ͑i.e., the floors comprising Part C͒
would be more likely than the lower floors to deform and
yield during collapse” ͑deform they could, of course, but
only a little, i.e., elastically͒.

More-detailed calculations than those
included in their paper were made by Bažant and
Verdure to address this question. On the basis of a simple
estimate of energy corresponding to the area between the
load-deflection curve of columns and the gravity force for
crush down or crush up, it was concluded at the onset that the
latter area is much larger, making crush-up impossible."


His words, not mine.

Would you like to see Bazant's proof as to why crush up is impossible? He has a few of them.

Yes, it's impossible for the apple to deviate from the vertical, in a model that doesn't include wind. SO WHAT? That doesn't make the model incorrect or worthless.

______________​

Nonsense.

Apple from the top of WTC1...

With *wind* (air resistance) ~17.5s

I didn't say from the top of *WTC1*. I said from the top of *a building*.

Why do you keep making straw man attacks on what I am saying?

Hm, forget it, no need to answer actually.

If what you are implying is that his model is not useful to predict other magnitudes such as the ones calculated in BLGB, so far you haven't given a single reason to think that.

 

[pgimeno]

Please show your working.

Dave

I don't think there's a point to doing that, since it's anyway a misrepresentation of my parallel example.