OOS Collapse Propagation Model

[JSanderO]

ROOSD is a narrative, it has no physical-mathematical version where energy is mentioned or accounted for. Correct? So that's the trivial explanation for the "ROOSD does not (matches energy values)" part.

ROOSD seems to me to be a basic description of *mechanism(s)* how long span hull and core buildings (twin towers) with light weight concrete floor slabs "collapse".

But it collapses as it does because.... of the nature/attributes of the design.

 

[Crazy Chainsaw]

ROOSD is a narrative, it has no physical-mathematical version where energy is mentioned or accounted for. Correct? So that's the trivial explanation for the "ROOSD does not (matches energy values)" part.

I think Bazant does match energy values. But I could be mistaken.

It matched the energy values in the three dimensional computer model developed,
By Greening and Benson, the paper BLGB is an abstract on that model.
Not the computer model itself which is more complex.

ROOSD floor shearing does not match the model, to fast unless other energy sources are in play.
The BLGB model assumes buckling leading to core failure though off center impacts in
Core destroying, beams and even core column welds.
It does not assume strictly buckling of core columns.
The paper is an abstract, not the actual computer program.

 

[Crazy Chainsaw]

The seismic "data" is fuzzy..... the first possible "seismic" sign would be when the first HEAVY steel from the "upper section" hit the ground. This was at least... assuming that there heavy steel immediately tossed over... about 9 seconds AFTER the top was visibly moving downward.

When was the "last" seismic signature?

You don't think the snap of the core column would be transmited by the steel, like the planes impact was?

 

[JSanderO]

You don't think the snap of the core column would be transmited by the steel, like the planes impact was?

I have absolutely no expertise in such things. My hunch is that the seismic data could not determine the collapse time with any precision. And could not record the snap of one steel beam or column what ever that would be. The plane impact was energetic enough to cause the building to sway and perhaps this could be recorded by the sensors.

dunno.

 

[Crazy Chainsaw]

I have absolutely no expertise in such things. My hunch is that the seismic data could not determine the collapse time with any precision. And could not record the snap of one steel beam or column what ever that would be. The plane impact was energetic enough to cause the building to sway and perhaps this could be recorded by the sensors.

dunno.

The start of the collapses was ten to twenty times the energy of the planes impact, and your saying it would not be recorded ?

 

[Crazy Chainsaw]

From BLGB,

Comparison of Collapse Duration with Seismic Record
Calculations show that the duration of the entire crush-down phase exceeds the free fall duration
by 65.5% for the North Tower, and by 47.3% for the South Tower (Fig. 8). This is a signif-
icant difference, which can be checked against seismic records registered at Lamont-Doherty
Earth Observatory of Columbia University (http://www.ldeo.columbia.edu/LCSN/Eq/WTC
20010911.html), shown in Fig. 8. In a detailed seismic analysis at Columbia University, Kim
et al. (2001) report that, because of short travel distance and shallow excitation, the recorded
seismic waves were short-period Rayleigh surface waves (which generally travel within the upper
few kilometers of Earth crust). No pressure and shear waves were registered.
The first tremor in Fig. 8, which is weak (and is marked as a), is assumed to represent t = 0,
i.e., the moment of impact of the upper part of tower onto the lower part (a correction of 0.07
s is made for the delay due to the travel time of the sound wave along the steel columns to the
ground). The sudden, though mild, displacement increase at instant b (Fig. 8) is attributed to
free falling large structure segments that hit the ground outside the tower perimeter.
The free fall times for the fragments ejected at the 96th and 81st stories are 8.61 s and 7.91
s, respectively (the air drag is negligible for multi-story pieces of the steel frame). These times

 

[JSanderO]

The start of the collapses was ten to twenty times the energy of the planes impact, and your saying it would not be recorded ?

The top falling on the bottom section was the start? Yes?

 

[Crazy Chainsaw]

The top falling on the bottom section was the start? Yes?

Then that impact was recorded in the seismic data.

 

[Major_Tom]

This thread was reopened by me on page 67. I presented a list of quotations from Closure to 'Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions' by Zdenek P. Bažant and Mathieu Verdure by Zdenek P. Bazant and Jia-Liang Le (BL), published in 2007,

I also presented a list of 44 highly specific questions about information within the quotes presented. The quotes directly from the paper and the 44 questions are at this link.



I also presented direct quotes from David Benson, co-author of What Did and Did not Cause Collapse of WTC Twin Towers in New York, by Zdenek P. Bazant, Jia-Liang Le, Frank R. Greening and David B. Benson (BGLB).

The direct quotes are from an exchange he had with me after his paper was published. I also presented a list of 30 highly specific questions about information within these quotes. The quotes directly from David Benson and the 30 questions are at this link.




The direct quotes and questions were carefully chosen to allow anyone with a sincere interest in the subject of the Bazant papers on the WTC collapses published from 2007 to the present to see these papers for what they really are.





It is quite interesting to contrast the direct quotes from both Bazant and Le and BLGB co-author David Benson with collected statements which represent the way that this same paper is perceived within the JREF/ISF environment:


Newtons Bit comments
R Mackey comments
Dave Rogers and Myriad comments



These simple quotes and questions, directly contrasted with the JREF'ISF systems of belief as expressed in the collected statements, can help the more sincere observers among the readers, truther, debunker, or more non-attached honest observers curious about the written history of the WTC collapses, to disabuse yourselves of the talking points to which you have been subject for years.

This set of talking points, or 'memeplex', is so transfixed within this forum that it is now a permanent state. I sympathize with regular readers of this forum and anybody subject to environments like this since the atmosphere is one in which people are drowning in talking points, or memes, of their own creation.

For this reason I've devised a simple step-by-step system in which I will use the Bazant and Benson quotes and directly contrast them with the collected JREF/ISF quotes. These contrasting quotes, along with simple questions about the quotes, may help some readers free themselves from the JREF/ISF talking points. Others, of course, identify themselves so deeply with the JREF/ISF talking points that they will defend the memeplex no matter what.

Let's go over these quotes and questions one by one.

 

[ozeco41]

"The later papers by Bazant et al are wrong if and whenever they apply 1D simplification models to the WTC real event".

For the record:
I am of this opinion too - and arrived at it because long ago you, ozeco, and not M_T, provided me with convincing arguments to override the tentative authority of Bazant.

Thanks Oystein. You are aware of my primary interest in these topics which is in understanding and explaining the engineering physics of the events.

Now I find myself under personal credibility attacks from three members. I am confident that those hostilities are unwarranted - in fact I've just drafted a reasoned rebuttal to all three BUT it goes against my grain - my values - to even bother defending such issues which are Off Topic.

My aim throughout has been to establish agreed clarity on some foundation technical issues. The one you quote and agree to is the second stage.

This thread is a confusing mess of partial understanding and different agendas. IMO many of the confusions and crossed agendas would be resolved or much easier to address if we could agree the core facts which flow from the OP.

Do you agree with the objective of reducing conflict and confusions?
Do you agree that agreeing the foundation facts would help?
Do you agree to these which I suggest are base level facts relevant to the OP?
(And if you are not comfortable with the word fact please suggest another label.)

Fact #1a Bazant in B&Z identified that the real collapse mechanism was complicated and chose a simpler model which was valid for a "limit case argument";

Fact #1b Bazant in B&Z clearly distinguished the two different mechanisms - the more complicated real event and the simpler version supporting a "limit case" argument;

Fact #1c Bazant's "limit case" argument was conceptually valid, it has not been successfully challenged and he did not confuse the two mechanisms.

"Fact" #2 Discussion of WTC collapses should not use or rely on confusion of any issues of fact including the facts derived from Bazant's work. << OK - this one is a procedural rule - not necessarily a "fact"

Fact #3 - The progression collapse stage for WTC1 and WTC2 was dominated by a mechanism in which material falling down the office space tube stripped floors leaving perimeter columns to fall away.

Fact #4 The real event collapse described by Major_Tom in the link from the OP AND restated as Fact #3 is a different mechanism to the column crushing model of the limit case argument.

Fact #5 Reaffirms that the two mechanisms are different - and that M_T and ozeco agree - not directly relevant here.

"Fact" #6 Arguments should not be confused over the two mechanisms and any relationship they may have. << Yes another procedural rule

And an "incidental issue" - which goes to the use of the label "ROOSD". << Also a procedural matter - the relevant aspect is that whatever label is applied has zero effect on the technical reality.

M_T quoted (incompletely) and misrepresented a post I made 4.5 years ago in which I questioned his methodoology. By way of example, I picked one question he posed about BL, criticized a methodological flaw in the question (he asked for belief, not claims or arguments), and advised him on how to convince fence-sitters like I was at the time (fully admitting to my lack of competence and information). I don't think M_T heeded that advice back then (but I can't be bothered to check). I guess it must have hurt his butt that I, the incompetent newbee, advised him on methodology, so much that even today, 4.5 years later, he keeps riding that dead horse.

Ryan Mackey slapped me down as a newbie on an engineering matter where I was right and he was wrong. A clear cut case of lèse majesté by me. I plead guilty. I had to be told of my proper place in the "pecking order". I'm not into ego games. I comprehend the sins of M_T's posting. It is almost certain that he has attacked me more than any other member. You may rank #2. I'm trying to avoid getting even with M_T. If that is necessary - split the thread. Let's try for agreement on the technical issues.

Now I jumped into this thread with both feet in response to a reply you made to Myriad, showing you how you badly misrepresented what he wrote by pretending Myriads scope was wider than it actually was. You have made, and repeated, claims about Myriads past posting (insinuating that he "rested" stuff on BV), but failed to support these claims with evidence, as Myriad asked you to do several times.
I think you and M_T are totally misreading Myriad because you both fail to read him with your meme-blinders off.

I fully understand your position and it saddens me. I don't want to publish the full rebuttals of three members claims about my alleged sins. Especially when all the alleged offences occurred when my accusers had already pushed us way off the theme. From my perspective all three have arisen when members have challenged or requested my to explain something and I have provided detailed reasoned responses which those members have ignored. The evidence of that initial discourtesy and the progressive deterioration and drifting further off track leading to personal insults is fully documented.

I do not wish to go there. If you want to push the issue we would do better on a different thread. I don't think that path is appropriate. At the least can you and I call a halt to the personal stuff?

Oh, and yes, this all about settling scores

I'll take that comment as intended humour.

 

[ozeco41]

Let's go over these quotes and questions one by one.

Major_Tom why not start at the beginning:

1) What is your objective? What are you trying to prove?

That one should be a concise statement in one sentence.

THEN

2) What is your claim?

That one should be the "executive summary" in no more than one paragraph of 2-3-4 sentences.

THEN you can present the outline of your proposed lines of argument at which stage there may be something to discuss.

Now - whilst you are at it - do you agree that these are true facts or valid rules for discussion:

Fact #1a Bazant in B&Z identified that the real collapse mechanism was complicated and chose a simpler model which was valid for a "limit case argument";

Fact #1b Bazant in B&Z clearly distinguished the two different mechanisms - the more complicated real event and the simpler version supporting a "limit case" argument;

Fact #1c Bazant's "limit case" argument was conceptually valid, it has not been successfully challenged and he did not confuse the two mechanisms.

Procedural Rule #1 Discussion of WTC collapses should not use or rely on confusion of any issues of fact including the facts derived from Bazant's work.

Fact #3 - The progression collapse stage for WTC1 and WTC2 was dominated by a mechanism in which material falling down the office space tube stripped floors leaving perimeter columns to fall away.

Fact #4 The real event collapse is a different mechanism to the column crushing model of the limit case argument.

Procedural Rule #2 Arguments should not be confused over the two mechanisms and any relationship they may have.

AND this one:

"The later papers by Bazant et al are wrong if and whenever they apply 1D simplification models to the WTC real event".

 

[Oystein]

Thanks Oystein. You are aware of my primary interest in these topics which is in understanding and explaining the engineering physics of the events.

You're welcome, and yes.

Now I find myself under personal credibility attacks from three members. I am confident that those hostilities are unwarranted - in fact I've just drafted a reasoned rebuttal to all three BUT it goes against my grain - my values - to even bother defending such issues which are Off Topic.

Difficult to tell what is on- and off-topic in this thread (JREF/ISF has long held that the topic of a thread may drift somewhat from the OP, or that the OP are not entitled to have their interpretation of the topic upheld).

My aim throughout has been to establish agreed clarity on some foundation technical issues.

This is all good and well, but you cannot impose your foundation onto others.

This thread is a confusing mess of partial understanding and different agendas.

Absolutely.

IMO many of the confusions and crossed agendas would be resolved or much easier to address if we could agree the core facts which flow from the OP.

I am not sure that the agenda that I am currently following can be thus resolved (and thus may well be / probably is off-topic).

Do you agree with the objective of reducing conflict and confusions?
Do you agree that agreeing the foundation facts would help?

Yes to both.

Do you agree to these which I suggest are base level facts relevant to the OP?
(And if you are not comfortable with the word fact please suggest another label.)

Relevant to the OP, less relevant to resolving the issue of memetics, groupthink, anthopology, dishonesty and allegations about what Myriad does or does not rest certain claims upon.

Ryan Mackey slapped me down as a newbie on an engineering matter where I was right and he was wrong. A clear cut case of lèse majesté by me. I plead guilty. I had to be told of my proper place in the "pecking order".

My sympathies.
I arrived here at a time when RMackey reigned as king, but not long before he departed. At the time, I was still in the steep part of several learning curves. Some of the engineering arguments were way over my head, some I learned to comprehend soon. I don't think I was influenced in my thinking about collapse progression by RMackey, I came too late for that and/or did not read or understand the arguments exchanged. I remember having read, and tentatively accepting, his analysis of how 767 wings would cut through 14" steel columns. he modelled the wings basically as merely the fluid they contained, and reduced the hollow columns to an equivalent solid plate, IIRC. The model seemed appropriate, the analysis sufficiently thorough, and the counter-arguments of such poor quality that I went away convinced the analysis is good enough to justify belief in the conclusion that yes, those jet wings travelling fast enough will sever steel columns and still retain much of their kinetic energy. So from that I induced that RMackey is capable of doing solid engineering/physics analysis in such matters.
But again, I don't think I have followed him in any debates on collapse progression.

I'm not into ego games. I comprehend the sins of M_T's posting. It is almost certain that he has attacked me more than any other member. You may rank #2. I'm trying to avoid getting even with M_T. If that is necessary - split the thread. Let's try for agreement on the technical issues.

On one hand, I agree that splitting the thread would improve the level of debate both on the technical issues (despite their goin' 'round'n'round) and on the "memeplex". I am not sure on the other hand that there is a place/subforum here where the latter would fit and stay within the MA.

I fully understand your position and it saddens me.

This is precisely what I doubt, and I claim the opposite: I do not believe you understand my position! If you did, you would have said by now "ahhh - now I get it" and revised your position.

I don't want to publish the full rebuttals of three members claims about my alleged sins. Especially when all the alleged offences occurred when my accusers had already pushed us way off the theme. From my perspective all three have arisen when members have challenged or requested my to explain something and I have provided detailed reasoned responses which those members have ignored.

I think I have not ignored your "detailed reasoned response", instead I rejected it in its entirety because I felt it was so far off the mark, there was no point in addressing it in detail. You followed up with a lengthy proposal on how to procede, and yes. I ignored that - partly because it would have required more time in one piece than I had then (several days ago) (my apologies for that), partly because I don't know how to procede. I don't know how to express my position any clearer than I already have, so my best idea is to say "put your blinders off, and read the exchange of the last ... urrr 10 days or what was it, again".

The evidence of that initial discourtesy and the progressive deterioration and drifting further off track leading to personal insults is fully documented.

I do not wish to go there. If you want to push the issue we would do better on a different thread. I don't think that path is appropriate. At the least can you and I call a halt to the personal stuff?

I think I see a pattern in your posting in recent weeks and months that you attribute "Bazantianism" to other folks' posts where none is intended, or take references to Bazant, or terms appearing somewhere in Bazant's papers, farther than intended by those using them. You seem to assume - often falsely - that when someone discusses some detail of some Bazant paper (like Myriad recently did), they mean to apply that bit as part of an explanation of some observed feature of the real collapses.
Or, you drag in Bazant, only to reject his work, in discussions where no one makes reference to Bazant - essentially a kind of strawman argument.

I have alerted you to this a few times.
I will continue to alert you to this when I think you are committing this error again.

But I agree to "halt the personal stuff" between you and I - with the disclaimer that pointing out what I believe to be an error in something you say is NOT "personal stuff" - and observing that you commit the same alleged error repeatedly, that there seems to be a pattern, likewise needs not be "personal".

I'll take that comment as intended humour.

Humour yes in that I can laugh about myself here, BUT true regardless.

 

[Oystein]

As for ozeco's facts and procedural rules:

Fact #1a Bazant in B&Z identified that the real collapse mechanism was complicated and chose a simpler model which was valid for a "limit case argument";

Fact #1b Bazant in B&Z clearly distinguished the two different mechanisms - the more complicated real event and the simpler version supporting a "limit case" argument;

Fact #1c Bazant's "limit case" argument was conceptually valid, it has not been successfully challenged and he did not confuse the two mechanisms.

Procedural Rule #2 Discussion of WTC collapses should not use or rely on confusion of any issues of fact including the facts derived from Bazant's work.

Fact #3 The progression collapse stage for WTC1 and WTC2 was dominated by a mechanism in which material falling down the office space tube stripped floors leaving perimeter columns to fall away.

Fact #4 The real event collapse is a different mechanism to the column crushing model of the limit case argument.

Procedural Rule #5 Arguments should not be confused over the two mechanisms and any relationship they may have.

Fact #6 The later papers by Bazant et al are wrong if and whenever they apply 1D simplification models to the WTC real event".​

What I colored red is numbers I changed or added. I propose to use these for the sake of clarity and continuity.


I agree to all, with the usual disclaimer that I have not read or sufficiently understood the later papers to base this agreement on my own understanding, but the arguments presented here and elsewhere seem convincing enough to me; plus, my perception is that this is also rather uncontroversial among posters here today, including several whose judgement in such matters I trust to some degree based on past experience.

 

[Crazy Chainsaw]

As for ozeco's facts and procedural rules:

Fact #1a Bazant in B&Z identified that the real collapse mechanism was complicated and chose a simpler model which was valid for a "limit case argument";

Fact #1b Bazant in B&Z clearly distinguished the two different mechanisms - the more complicated real event and the simpler version supporting a "limit case" argument;

Fact #1c Bazant's "limit case" argument was conceptually valid, it has not been successfully challenged and he did not confuse the two mechanisms.

Procedural Rule #2 Discussion of WTC collapses should not use or rely on confusion of any issues of fact including the facts derived from Bazant's work.

Fact #3 The progression collapse stage for WTC1 and WTC2 was dominated by a mechanism in which material falling down the office space tube stripped floors leaving perimeter columns to fall away.

Fact #4 The real event collapse is a different mechanism to the column crushing model of the limit case argument.

Procedural Rule #5 Arguments should not be confused over the two mechanisms and any relationship they may have.

Fact #6 The later papers by Bazant et al are wrong if and whenever they apply 1D simplification models to the WTC real event".​

What I colored red is numbers I changed or added. I propose to use these for the sake of clarity and continuity.


I agree to all, with the usual disclaimer that I have not read or sufficiently understood the later papers to base this agreement on my own understanding, but the arguments presented here and elsewhere seem convincing enough to me; plus, my perception is that this is also rather uncontroversial among posters here today, including several whose judgement in such matters I trust to some degree based on past experience.

Sorry Oystein, the part I marked in yellow agrees with BLGB as well as ROOSD.
If your going to comment you should Read BLGB, the argument for treating the floors as a homogeneous mass is the same for the planes wings though the towers steel.
It would give you a better understanding of the physics but remember it is an abstract,
Of a computer model not the model itself.
I think most of the confusion is do to lack of information, people not actually understanding how close the computer model compares to ROOSD.

Both suppose debris running down the outer tube, only one gives mathematical values
And collapse time.

The drawings in the paper are just simplification of concept being mis interpreted here.

ROOSD, and BLGB are like twins, both wearing similar outfits, mirror images almost.

All that is needed to bring them together is Resistance, and fluid dynamics, to disrupt the Homogeneous mass
and induce more mass shedding of the upper block vs mass shedding of the structure below the homogeneous
Mass of crushed floors.
Basicly the light weight concrete and drywall of the floors is too weak to remain as large chunks in the collapse front and the trusses insignificant.
The floors should be overloaded before outer perimeter columns can fall inwards.

Mass loss of the upper block can not exceed 6 percent in column fracture or collapse time changes as well,
The mass of the upper block drives the collapse, though the resistance of the buildings below.
That mass has to be maintained, and most mass shedding has to occur below the collapse front,
Which ever mechanism is proposed it has to comply with the laws of physics.
I see very little work on MT's part, to reconcile his mechanism with the observed data from the
Seismic record, he seems to be solely describing, resistance effects, and fluid dynamics effects that
Were to complex, for computer modeling because of the added data they represent.
He seems bent on a mission of one up man ship, not on a quest of scientific discovery.
I sincerely doubt that MT, or Ozeco41 have seen the actual computer model that the
BLGB, have seen the Greening, Benson computer programs.
I believe they are just commenting on the simplified abstract of those programs.

 

[Crazy Chainsaw]

You can't judge a book by the cover, and you can not judge a computer program by an abstract, that is
Only meant to help people understand it.

Major Tom your work could be of value for understanding as distribution of material do to structural resistance
and fluid dynamics, if you drop the false implications and memes that you yourself apply to it.
If I were you I would find a copy of the Benson Greening computer model, and see how that marches your observations of mass distribution in the collapses, the computer model is more complicated than the simple abstract paper.

 

[pgimeno]

Let's go over these quotes and questions one by one.

I already did, for the 44 in the BL pack, at this link. What do you want to do now? Substitute reality with your own prejudiced view on the way this forum's members, as a block (oh the irony), perceive the collapses?

I don't care what Benson thinks, he's not me and he doesn't represent me. So I didn't really try to answer the questions asked about him.

 

[Oystein]

Sorry Oystein, the part I marked in yellow agrees with BLGB as well as ROOSD.

Why sorry? If this is true, that would be wonderful

If your going to comment you should Read BLGB, the argument for treating the floors as a homogeneous mass is the same for the planes wings though the towers steel.
It would give you a better understanding of the physics but remember it is an abstract,
Of a computer model not the model itself.

Before I comment directly on BLGB, or BV or BL, I will read them, or the relevant parts.
I am currently more interested in the positions about BXYZ that M_T, and sometimes ozeco, ascribe to some posters - myself included. I know that M_T keeps misrepresenting my position. I think they have most recently misrepresented Myriad.

This is a call to all parties to take off blinders and consider the possibility that perhaps we are mutually projecting our prejudices at each other.

 

[Bravin Neff]

Let's go over these quotes and questions one by one.

I already did.

Your answers didn't fit inside the fake debunker-subculture-anthropology theme, so that isn't gonna work.

 

[Major_Tom]

I already did, for the 44 in the BL pack, at this link. What do you want to do now?

Nothing. You have already answered. Bravin agreed with all your answers so he answered too.

I don't care what Benson thinks, he's not me and he doesn't represent me. So I didn't really try to answer the questions asked about him.

As you wish. He is the co-author with Bazant of BLGB, and his quotes contradict pretty much everything you wrote in your answers about BL, but do whatever you think is best.

 

[Major_Tom]

Let's start with a few quotes by David Benson from the links given earlier.




David Benson on WTC1:

"OneWhiteEye --- I'm not the one with any doubts about the matter: there can be no significant early crush-up."

from this post


Question 13: Within this statement does David Benson explicitly state that there can be 'no significant early crush up' and that he has 'no doubts' about that claim?



David Benson on WTC1:

"Read Bazant & Le to understand why zone C can be consired to be essentially rigid during crush-down.
I offered to start a thread about how to build a table-top demonstrator that will allow one to see that,
indeed, zone C remains intact during crush-down. I didn't bother when I realized that nobody here would bother to actually build it, test it, and in the process dicover that the application of Newton's laws and
d'Alembert's principle in Bazant & Verdure agrees with reality."

from this post


Question 14: Within this comment does David Benson state that the Bazant and Le paper contains the information that can help one understand why the WTC1 'upper block' (zone C) can be considered to be 'esentially rigid' during 'crush down'?

Question 15: Does he also state he considered starting a thread on how to build a table-top generator which would allow one to see that "indeed, zone C remains intact during crush-down."

Question 16: When David Benson refers to "reality" in this quote, is he referring to the actual collapse of WTC1?

>>>>>>>

My answers are: Yes, yes, yes, and yes.

I'd really like to read what others have to say.