Merged Applicability of Bazant's model to the real world

[leftysergeant]

Bazant's work is valid as far as it concerns calculating the amount of energy avaialble to the work of crushing the towers. In thereal world, such progressinve collapses would almost invariably procede as Bazant described.




Where it all falls apart, regarding the towers is in the fact that, unlike most buildings, the centers of the towers offered the greatest resistance and thus started crushing up almost at once. This destroyed any structural integrity the top portion would have had, causing it to discombobulate almost at once so that you have rubble rather than a solid block of building.

But the mass does not go away. It stayed there inside the perimeter columns until it shoved the perimeter columns out of the way.

At any rate, idiot boy Gage's work depends on Bazant's model being wrong in every case, which is the point of little Dickie's cardboard box drop. But verinage is a direct application of the principles that Bazant applies.

 

[leftysergeant]

Absolutely. It's a pleasure to see the Bazant distraction being frogmarched out of the real-world event.

Nothing of the sort. Bazant's values were right. Twoofers, especially Gage, are wrong. The energy is there and is transferred at the rate at which Bazant supposes. Just that nasty center structure reducing the top to a mass of rubble (which is still substantial, ) rather than a (far less dense) empty block.

The upper columns, being more badly distorted, separated easily on contact with the lower columns, thus robbing the whole upper bl;ock of its rigidity.

 

[ozeco41]

Bazant's work is valid as far as it concerns calculating the amount of energy avaialble to the work of crushing the towers. In thereal world, such progressinve collapses would almost invariably procede as Bazant described....

I agree broadly with this.
1) There is no doubt as to "...amount of energy available to the work of crushing the towers..."
2) IMO the main reason most real world progressive collapses would probably progress as per Bazant is that most real world towers are not tube in tube design. Two aspects of collapse follow from the difference.
(a) "normal" buildings with columns and beams in a grid arrangement would act closer to homogeneous than the tube-in-tube of WTC1 & 2 and Bazants base assumption of axial loading of columns would be most likely valid or very close approximation; CONTRAST
(b) WTC 1 & 2 where the vulnerability to collapse was implicit in the tube-in-tube design and there was no axial loading of outer tube columns and (by reasoning) few if any core columns. (The former by observation of evidence - the latter by reasoning.)
Whilst my explantion would be somewhat different to this:

....Where it all falls apart, regarding the towers is in the fact that, unlike most buildings, the centers of the towers offered the greatest resistance and thus started crushing up almost at once. This destroyed any structural integrity the top portion would have had, causing it to discombobulate almost at once so that you have rubble rather than a solid block of building....

...I fully support the conclusion you reach:

...But the mass does not go away. It stayed there inside the perimeter columns until it shoved the perimeter columns out of the way....

or they simply fell over once the bracing from the floors was lost.

...At any rate, idiot boy Gage's work depends on Bazant's model being wrong in every case, which is the point of little Dickie's cardboard box drop. But verinage is a direct application of the principles that Bazant applies.

Yes, yes and yes.

 

[ozeco41]

Pgimeno and others,

On the question of applicability, we need to honestly recognize examples of people clearly crossing the line by applying the results of the Bazant 1-D stick model to real 3-D buildings...

Since I joined the public on internet debate of WTC and 9/11 my primary objectives have been (1) to answer the question "Demolition or Not?" THEN (2) Since there was no demolition, to understand and explain to myself and others why and how the Twin Towers fell.

I therefore approach the problem of (2) from the evidence as to what actually happened to WTC1 and WTC2 and I form conclusions as to the mechanisms involved. It is of interest to look at the analyses of other persons - independent of which "side" of the debate they occupy.

My approach therefore is to use theory if it is needed to support analysis of the actual events at WTC on 9/11. That is 180% opposite course to those who formulate theoretical solutions and try to fit them to the real events. And the distinction is not trivial.

To me the Bazant model has severe limitations in explaining the detail of how WTC1 and 2 fell. However the alternate approach by finite elements would be inordinately complex and would rely on so many assumptions about structural components which could not be observed as to make the exercise futile even if it was possible.

The broad parameters of the actual collapses are available in video evidence. Key among those bits of evidence is the fact that the bulk of descending mass passed down inside the outer tube. Allowing for the fact that the descent was probably mostly core on core and floor on floor it is readily argued that the floor on floor impact struck the lower floors seriatem one at a time. 10 or 20 floors hitting one floor dynamically does not need masses of calculations to prove "overwhelming load". Careful thinking about what happens to the core on core bits AND allowing for possibly some core to floor overlaps and a ball park explanation emerges. Key point being that the assumptions to support such ball parking are not any worse than the assumptions needed for Bazant modelling or finite element if anyone seriously considered it.

So, bottom line for me is that Bazant is of little value. He "proves" sufficient global energy to sustain collapse and that is all that is useful as secondary support to me as I seek to explain WTC Towers collapse. And my interest is explaining those collapses without demolition as a factor.

I have no interest in supporting Bazant any further. I am mildly frustrated by the number of threads which claim explicitly that they are supporting Bazant as a generic model but then go nice and ambiguous about what the assumptions of the model are and whether or not those assumptions limit the application of Bazant to WTC.

So I apply this form of test where people are arguing Bazant vis-a-vis WTC Twin Towers:
"Is the objective to defend Bazant or is it answer questions about WTC collapses?"

First 'Principle of War' (British and Aussie version) Selection and Maintenance of the Aim. The US version says the same thing in one word 'Objective'.

My objective is "Explain WTC Demolition or not?" - side line discussions about Bazant don't help. And I don't think Bazant's model fits WTC1 & 2 in any way which is of much help to me. And I tend to ignore attempts to apply Bazant in detail to WTC events.

So Mr Mackey's use of Bazant is his choice. He and I agree on the global outcome "no demolition". Nothing Mr Mackey posts weakens my position on no demolition. But nor does his use of Bazant modelling or Bazantphile concepts such as "crush up/crush down" change any of my understandings of what actually happened.
So:

...True or false? In the following quote R Mackey clearly crosses the line, ascribing attributes of the Bazant 1-D stick model to a 3-D description:...

..I skip over the Bazant stuff. And:

...I think this is a good example of how not to apply the crush down, then crush up attributes of the 1-D stick model to 3-D cases. Do others agree?

...personally I regard the whole "crush up/crush down" concept as commonly used in explanation to be as useless as the faeces of a male bovine. And on my favourite forums I could have used the blunt Aussie version of that word.

 

[Major_Tom]

Ozeco, as for the actual collapse propagation of the towers, have you read the OOS collapse propagation study in the OP of the "OOS collapse propagation model" thread?

If not, I think you will appreciate it in that it is the best overall descriptive collapse propagation model which matches all observables available.

Through the model you will see that I have no problem with runaway destruction of the towers. Neither do any of the researchers with whom I work and share information, many of whom at "truthers".

Many of us allow for runaway propagation to earth through the open office space (OOS) areas between the perimeter and the core all the way to earth.

Check it out in that I think you will like it.

Leftysergeant is describing much the same thing as the OOS model.

 

[beachnut]

Ozeco, as for the actual collapse propagation of the towers, have you read the OOS collapse propagation study in the OP of the "OOS collapse propagation model" thread?

If not, I think you will appreciate it in that it is the best overall descriptive collapse propagation model which matches all observables available.

Through the model you will see that I have no problem with runaway destruction of the towers. Neither do any of the researchers with whom I work and share information, many of whom at "truthers".

Many of us allow for runaway propagation to earth through the open office space (OOS) areas between the perimeter and the core all the way to earth.

Check it out in that I think you will like it.

Leftysergeant is describing much the same thing as the OOS model.

Got any evidence for your CD delusion yet? You waste time on Bazant when you should be critiquing your own failed conclusions.

 

[ozeco41]

Ozeco, as for the actual collapse propagation of the towers, have you read the OOS collapse propagation study in the OP of the "OOS collapse propagation model" thread?

If not, I think you will appreciate it in that it is the best overall descriptive collapse propagation model which matches all observables available....

I have read it. The part in the OP is brief and goes further into "what happened to the core" detail than I have considered necessary. I have also read the subsequent posts which expand on your explanation. It is however consistent with my explanations first published on the now defunct Richard Dawkins Net forum. I rewrote my explanation for essentially the same forum audience when many members of RDNet moved to "ratskep". The rewrite is here: http://www.rationalskepticism.org/c...-obligatory-9-11-thread-t515-680.html#p135852 As you will see my version is a reasoned analysis which does not resort to mathematics - consistent with my overall philosophy of "get the reasoning right before engaging maths" I wouldn't trust myself with maths these days on something as complex as WTC collapse - even if I made massive simplifying assumptions al la Bazant.

Through the model you will see that I have no problem with runaway destruction of the towers. Neither do any of the researchers with whom I work and share information, many of whom at "truthers"...

...we used to maintain a clear distinction between genuine sceptics who doubted the "no demolition" case and "truthers" or "CTs". So there were three camps back in 2007 when I first became involved in 9/11 discussions. (Probably four because many "CTs" pretended to be sceptics ) The distinction seems to have been lost over recent times - you are classified either as "debunker" or "truther" and often it seems that those with any doubt about the debunker gurus etc are classed as truthers.

Check it out in that I think you will like it.

...it is in same ball park as mine. My reasoning in the single post is lengthier than your OP standing alone. I have only skim read the extra explanation in later posts - methinks here is not the place for a critique.

Leftysergeant is describing much the same thing as the OOS model.

...sure looks like it to me.

 

[bill smith]

Nothing of the sort. Bazant's values were right. Twoofers, especially Gage, are wrong. The energy is there and is transferred at the rate at which Bazant supposes. Just that nasty center structure reducing the top to a mass of rubble (which is still substantial, ) rather than a (far less dense) empty block.

The upper columns, being more badly distorted, separated easily on contact with the lower columns, thus robbing the whole upper bl;ock of its rigidity.

Doesn't Bazant's theory depend on a 'rigid upper block' ?

 

[ozeco41]

Doesn't Bazant's theory depend on a 'rigid upper block' ?

"Rigid" is not the right word. "Integral" would be more appropriate. He takes as starting point that the 'upper block' was still structurally intact - ie not broken into component parts. He draws conclusions as to when it would break into component parts. BUT he accepts that interactions would be a mix of contacts involving elastic and plastic deformations. So "rigid" is not the word for a mix of elastic and plastic effects.

 

[Myriad]

Doesn't Bazant's theory depend on a 'rigid upper block' ?

Well, yeah. Bazant's best-case scenario for collapse arrest depends on the upper block remaining intact, so that all the impacts can be column-on-column and as much energy as possible can be absorbed in 3-hinge buckling of all the columns.

If the upper block falls apart, so does the best-case scenario -- making collapse arrest even less of a possibility.

Oops.

Respectfully,
Myriad

 

[bill smith]

"Rigid" is not the right word. "Integral" would be more appropriate. He takes as starting point that the 'upper block' was still structurally intact - ie not broken into component parts. He draws conclusions as to when it would break into component parts. BUT he accepts that interactions would be a mix of contacts involving elastic and plastic deformations. So "rigid" is not the word for a mix of elastic and plastic effects.

I'm sure that you will accept that a mixture of elastic and inelastic parts is basically only as strong as the elastic parts. (Chains and weakest links and so on)

So if 'Bazants's 'rigid' is only as strong as that I can see what you mean about 'rigid' not meaning 'rigid'. at all.

Are there any other words that are seriously misapplied by Bazant ?

 

[carlitos]

...we used to maintain a clear distinction between genuine sceptics who doubted the "no demolition" case and "truthers" or "CTs". So there were three camps back in 2007 when I first became involved in 9/11 discussions. (Probably four because many "CTs" pretended to be sceptics ) The distinction seems to have been lost over recent times - you are classified either as "debunker" or "truther" and often it seems that those with any doubt about the debunker gurus etc are classed as truthers.

I'm not sure how to take this aspect of Major Tom's theory. Maybe he has no claim at all, but he doesn't seem to rule out "a demolition team."

If unassisted ROOSD is possible, is this proof that the collapses were natural?

Not at all. It means that in the WTC1, 2 design a runaway destruction potential has always existed in the OOS spaces completely surrounding the cores which a demolition team can exploit by setting up sufficient initial conditions higher in the towers.

 

[bill smith]

Well, yeah. Bazant's best-case scenario for collapse arrest depends on the upper block remaining intact, so that all the impacts can be column-on-column and as much energy as possible can be absorbed in 3-hinge buckling of all the columns.

If the upper block falls apart, so does the best-case scenario -- making collapse arrest even less of a possibility.

Oops.

Respectfully,
Myriad

Isn't it amazing how easily the Bazant distraction gets overlaid onto the real event Myriad.

Why are we not talking about the hole in the building and where the 250 massive steel columns disappeared to- and all simultaneously at that.

That's the real mystery.

 

[Major_Tom]

Ozeco post 67: "As you will see my version is a reasoned analysis which does not resort to mathematics - consistent with my overall philosophy of "get the reasoning right before engaging maths".

I totally agree. An accurate description of the mass flow and the actions of perimeter, core in as much visual detail as possible.

THEN, when you feel you have something, you express it in mathematical form. I agree.

ROOSD has some very interesting mathematical properties. Excellent budding research by femr who has extracted the observed propagation front down the WTC1 SW corner over a good 40 floors. Bazant never had access to propagation data like this.

A basic mathematical model has been attempted on the data by OneWhiteEye of in The 9/11 Forum. Very early stages but some properties of ROOSD propagation have been identified by careful observation.


Ozeco: ".we used to maintain a clear distinction between genuine sceptics who doubted the "no demolition" case and "truthers" or "CTs". So there were three camps back in 2007 when I first became involved in 9/11 discussions."

I call them: Tweedle-dee, Tweedle-dum and "other".

Tweedle-dee and Tweedle-dum are very loud but they are not very smart.

Richard Gage is Tweedle-dee.


In my opinion the best part of the debate is done off stage by independent researchers.

Tweedle-dee and Tweedle-dum are just a side show, a (really big) distraction.

 

[Myriad]

Why are we not talking about the hole in the building and where the 250 massive steel columns disappeared to- and all simultaneously at that.

Because you asked about the upper block.

Now you're asking why I didn't abruptly change the subject? Because I rely on you for that. Specialization and division of labor promotes efficiency. I answer your questions, you abruptly change the subject. That's how it works, why change?

Respectfully,
Myriad

 

[Major_Tom]

Myriad, a "block" is a 2 or 3 dimensional object. There are no blocks in 1 dimension.


I thought we already agreed that the Bazant crush up, crush down equations of motion and the concept of crush down, then crush up are true only for a 1-D stick model based on propagation by buckling upwards or downwards from the initiation point?

Significant crush up cannot occur because the upwards force is insufficient to buckle the columns upward in the stick model as explained in BV.


Now the same thing applies to 3-D blocks (and to real buildings, too???)

 

[ozeco41]

I'm not sure how to take this aspect of Major Tom's theory. Maybe he has no claim at all, but he doesn't seem to rule out "a demolition team."

From what he posts his logic has not, at that stage, ruled out demolition.

In my own explanatory posts I routinely leave the option of demolition open until I have reached the stage where demolition can be ruled out. Call it "honesty in debate" or some such ethical scruple. I don't like presuming that which I have not shown if it is a central issue under contention. For brevity in debate I will often make assertions on secondary matters on the implied or explicit justification that I am prepared to give "proof" if called on.

So, for an example, "The initial collapse stage for the twin towers, the stage where the top block started to fall, resulted from some process weakening the structure in the impact zone. That process was either aircraft impact damage plus accumulated fire damage alone OR the same impact and fire damage PLUS assistance from demolition...."
...should not be read as me supporting demolition. I am simply leaving one option open because at that stage it is still a possibility of logic.

 

[Myriad]

Well, yeah. Bazant's best-case scenario for collapse arrest depends on the upper block remaining intact, so that all the impacts can be column-on-column and as much energy as possible can be absorbed in 3-hinge buckling of all the columns.

If the upper block falls apart, so does the best-case scenario -- making collapse arrest even less of a possibility.

Oops.

Myriad, a "block" is a 2 or 3 dimensional object. There are no blocks in 1 dimension.

I thought we already agreed that the Bazant crush up, crush down equations of motion and the concept of crush down, then crush up are true only for a 1-D stick model based on propagation by buckling upwards or downwards from the initiation point?

Significant crush up cannot occur because the upwards force is insufficient to buckle the columns upward in the stick model as explained in BV.

Now the same thing applies to 3-D blocks (and to real buildings, too???)

Since you started your post with my username, I get the impression that you were intending to reply to my post, but I don't see any connection at all between my post and your response.

Three-hinge buckling is definitely part of Bazant's collapse model, and three-hinge buckling definitely cannot take place in one dimension, so any claim to the effect that every aspect of Bazant's collapse model is limited to one dimension is clearly false. Does that help?

Respectfully,
Myriad

 

[beachnut]

... In my opinion the best part of the debate is done off stage by independent researchers.

Tweedle-dee and Tweedle-dum are just a side show, a (really big) distraction.

Are you tweedle-dum? The debate? lol, there is no CD, it is a delusion since you have no evidence. Yes the best place to debate the insanity of CD is off stage at some forum where nonsense is weighed equally with reality.

8 years of no evidence and you think you can debate CD. And you are serious. Have you dropped the insane CD claims yet? No.

The best you can do is attack Bazant's model. Any plans for attending engineering school?

CD was ruled out on 911, anyone who can't figure that out lacks knowledge, can't process evidence, lacks logical thinking skills, and the ability to leave their paranoid conspiracy theory past behind.

 

[leftysergeant]

Myriad, a "block" is a 2 or 3 dimensional object. There are no blocks in 1 dimension.


I thought we already agreed that the Bazant crush up, crush down equations of motion and the concept of crush down, then crush up are true only for a 1-D stick model based on propagation by buckling upwards or downwards from the initiation point?

Significant crush up cannot occur because the upwards force is insufficient to buckle the columns upward...

It isn't like the bottom is supposed to act like a rocket driving upward at the falling block. The idea behind explosive CD and verinage is that the top part, once disconnected from the foundation and dropped with some force, will be unable to support its own weight, thus will crumble as it comes into contact with the ground.

For what you claim to be true, the upper block must still be capabable of standing as a complete structure, after having dropped the distance described. Clearly, it is not.

As far as I can see, you are arguing for survival of most building in explosive CD or verinage.