OOS Collapse Propagation Model

[ozeco41]

It's not (actually) the destruction of the connections... it is destruction and grinding of the floor slabs themselves turning the floor mass (over a very compressed time) into a destructive "FLUID" which flows... in a contained vertical avalanche.

Sander your practice of disagreeing with both "sides" by raising a different explanation is confusing. Whether it is WTC 7 transfer trusses or this case details of ROOSD. I don't think you are right - BUT even if it is plausible it makes zero difference in the bigger picture.

Can you take a rain check? There are more important issues to resolve at this stage.

 

[DGM]

@Major_Tom your style of asking apparently loaded questions without a clear statement of your claim and passing "burden of research proof" to us has resulted in the usual mix of emotive personal comments and technical partial truths. If that was your intention I deplore it...again.

Has there ever been anything else?

If you are seeking clear understanding of the technical issues why not state them? Clearly and explicitly?

Never going to happen. It's all about how we don't understand and pointing out how we don't understand how his superior mappings point out how everyone else does not understand.

That reminds me, He never answered how he can support his claim that this was all due to a design flaw no one has accepted responsibility for.

 

[ozeco41]

Agreed, to all of the above. The discussion is about a specific model which is offered as a useful approximation to the actual collapses. The fact that other models exist, or may exist, isn't the topic of the discussion; indeed, I think a responsible editor would prefer such other models to be excluded from a discussion of a specific paper, because they're not part of the model under discussion.

Dave

Dave let me put my position clearly on record (again ).

That hilited aspect is I think the only technical issue where I seem to have a different opinion to most of the technically proficient members posting.

Most seem to accept that the approximations are valid - or "good enough".

I am not convinced that the two main approximations are good enough. They may well be - but I would like to see the factor both recognised and validly argued.

The two main aspects are:
1) I am not persuaded that a mechanism based on column crushing can validly represent even as an approximation for a mechanism which was dominated by floor joist shearing. I will not take it on the basis of bare assertions. Or implications. So I will maintain my reservations until I see and am persuaded by valid argument.

The associated issue is that I also hold reservations about testing the assumed approximation against the WTC collapse dynamics - velocities and timings. I am not persuaded that the tests are not giving "right results for wrong reasons" which is an invidious error often present in engineering.

2) The second main issue is that both stages of WTC Twins collapse were not 1D. Initiation cannot be rigorously explained using less than 3D and progression demands 2D - similar disclaimer comments to the above.

Both of those positions open to persuasive argument. If I ever see any.

I don't think there are any other issues of real disagreement provided we - all of us - avoid vague generalisations and are specific as to WTF we are talking about. Sadly clarity is not always there.

 

[JSanderO]

Ozzie,
Good summary.

For the twins:

I do have a beef with describing the floor collapse as "floor stripping" suggesting failure of the seats or connection to them. This did occur. But what is more characteristic of the collapse is the breaking up and communition of the floor slabs... grinding themselves into finer and finer grains and more less flowing much the way gravel flows through a hopper / chute.

++++

OT but it should be noted that the nature of the two debris piles of the twins and 7wtc was remarkably similar... all the slabs material ended up more of less the same.

Or were the different? Did 7wtc have more huge sections of slabs? If not why not and what does that tell about collapsing concrete floors?

 

[Crazy Chainsaw]

Ozzie,
Good summary.

For the twins:

I do have a beef with describing the floor collapse as "floor stripping" suggesting failure of the seats or connection to them. This did occur. But what is more characteristic of the collapse is the breaking up and communition of the floor slabs... grinding themselves into finer and finer grains and more less flowing much the way gravel flows through a hopper / chute.

++++

OT but it should be noted that the nature of the two debris piles of the twins and 7wtc was remarkably similar... all the slabs material ended up more of less the same.

Or were the different? Did 7wtc have more huge sections of slabs? If not why not and what does that tell about collapsing concrete floors?

The floors were light weight concrete and contained a lot of fly ash, if the floors were ground as you say they would have been dispersed shedding mass, and slowing the collapses, past the observed time.

 

[ozeco41]

Ozzie,
Good summary.

I think it is BUT:
A) Do you or do you not agree with the 8 points of fact I identified?

B) Have I missed any other points of relevant technical fact related to the use we make of Bazant and Zhou?

For the twins:

I do have a beef with describing the floor collapse as "floor stripping" suggesting failure of the seats or connection to them. This did occur. But what is more characteristic of the collapse is the breaking up and communition of the floor slabs... grinding themselves into finer and finer grains and more less flowing much the way gravel flows through a hopper / chute.

I understand your position as you have stated it many times. It is not relevant to my thesis. The engineering aspects critical to the collapse are: (i) The floors failed AND (ii) removed the bracing of the outer perimeter. Plus (iii) some secondary interactions with the core. Do you agree those three assertions (i), (ii) and (iii)?

OT but it should be noted that the nature of the two debris piles of the twins and 7wtc was remarkably similar... all the slabs material ended up more of less the same.

Or were the different? Did 7wtc have more huge sections of slabs? If not why not and what does that tell about collapsing concrete floors?

Correct - it is OT.

 

[ozeco41]

The floors were light weight concrete and contained a lot of fly ash, if the floors were ground as you say they would have been dispersed shedding mass, and slowing the collapses, past the observed time.

Sure - maybe - I doubt it. Respectively. But Sander is quite capable of going OT without help.

Do you agree or disagree the 8 facts I identified?

Are there any others I missed at that level of importance i.e. foundation premises? I'm not interested in minor details which are neither relevant nor significant.

 

[Major_Tom]

Good for you Major Tom, Oh no, I just realized, the ROOSD mechanics are the interior pancaking description of composite failure, described by Thomas Eggars, to me on the phone in 2005, if only he had drawn his own graphics,
Instead of allowing PBS to do it, the entire truth movement might have been avoided.

He should have. Do you mean Thomas Eagar?


He certainly should have made his position more clear publicly. Unfortunately, Thomas Eagar did make a public statement on the collapses which now exists as part of the written record.


Consider a Special Report published in the Journal of Engineering Mechanics in December, 2001:


Why Did the World Trade Center Collapse? Science, Engineering, and Speculation

Thomas W. Eagar and Christopher Musso

Journal of Engineering Mechanics

Feature: Special Report Linked here


Quote from the article:

THE COLLAPSE

...
As the joists on one or two of the most heavily burned floors gave way and the outer box columns began to bow outward, the floors above them also fell. The floor below (with its 1,300 t design capacity) could not support the roughly 45,000 t of ten floors (or more) above crashing down on these angle clips. This started the domino effect that caused the buildings to collapse within ten seconds, hitting bottom with an estimated speed of 200 km per hour. If it had been free fall, with no restraint, the collapse would have only taken eight seconds and would have impacted at 300 km/h.1 It has been suggested that it was fortunate that the WTC did not tip over onto other buildings surrounding the area. There are several points that should be made. First, the building is not solid; it is 95 percent air and, hence, can implode onto itself. Second, there is no lateral load, even the impact of a speeding aircraft, which is sufficient to move the center of gravity one hundred feet to the side such that it is not within the base footprint of the structure. Third, given the near free-fall collapse, there was insufficient time for portions to attain significant lateral velocity. To summarize all of these points, a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down.

This is a comment by Thomas Eagar in December 2001 which repeats many of the popular memes about the WTC1 and 2 collapse progression mode including

1) Crush front acceleration (near free fall) and velocity (increasing to near 200 kph)

2) On why the 'top part' didn't 'fall off' the 'bottom part' during the collapse progression process.

According to the article, there was 'insufficient lateral velocity' due to the 'near freefall acceleration`' of collapse and there was insufficient lateral load to move the 'center of gravity' of the 'upper portion' one hundred feet to any side. In short, 'a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down.'




These authors clearly did not understand of the process sometimes called "ROOSD" when making these comments. These explanations are primitive (and wrong) compared to what we can now verify.

>>>>>>>>


I have no doubt that you had an informative conversation with him at that time. But nobody has access to it now, and many, many people, including the generations following our own, have easy access to the 2001 Special Report published in the Journal of Engineering Mechanics, which repeats the same deceptive memes circulating elsewhere.

 

[beachnut]

...
I have no doubt that you had an informative conversation with him at that time. But nobody has access to it now, and many, many people, including the generations following our own, have easy access to the 2001 Special Report published in the Journal of Engineering Mechanics, which repeats the same deceptive memes circulating elsewhere.

Then publish this in the Journal. Prove your stuff, debunk those silly engineers.

What would be more interesting. When did you realize your claims of CD, the gravity collapse is an illusion meme, was BS? How did you figure out CD was a lie?

You left out your transition from full blown cover CD gravity collapse was an illusion believer to be the super debunker with the OOSCPM presentation. When, how and what made you drop the BS of CD?

 

[ozeco41]

....This is a comment by Thomas Eagar in December 2001 which repeats many of the popular memes¹ about the WTC1 and 2 collapse progression mode including

1) Crush front acceleration (near free fall) and velocity (increasing to near 200 kph)²
2) On why the 'top part' didn't 'fall off' the 'bottom part' during the collapse progression process.³
According to the article, there was 'insufficient lateral velocity' due to the 'near freefall acceleration`' of collapse and there was insufficient lateral load to move the 'center of gravity' of the 'upper portion' one hundred feet to any side. In short, 'a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down.'⁴

Major-Tom you persist in the same presentation style as many of your opponents - relying on vague and not specifically defined assertions. Most of them becoming partial truths because they are non specific and in that form they can be argued both ways. Some aspects may be true. Some possibly false.

I have repeatedly suggested that we need to be specific - or at least specific enough to avoid errors of false generalising or conflation.

Let's try this recent set of comments:

1 Why leave us guessing? Why not list the issues you consider to be memes in that referenced paper? Have you anywhere collated a list of issues which you regard as memes? If so where is it?

I'm fully supportive of the claim that discussion is "meme ridden" but your memes may not be the same ones as I would identify. Since you repeatedly raise the issues of memes please list the ones you identify for us. Preferably starting with the 4, 5 or 6 which you consider most important.

2 What is the "meme"? Yes the crush front had dynamics. Yes the dynamics included velocities. What is the meme? What aspect concrns you that you see a need to address?

3 Again what aspect of that reality is a "meme". Are you implying that explanations are false? Which explanations? Why are they false?

4 My own explanation - stated simply - says "once downwards falling starts (i.e. the top section falling bodily) the downwards vectors simply overwhelm the horizontal and rotational vectors". Do you agree or not? On what aspect do you disagree? What is fundamentally different between my explanation and the one you quoted?

These authors clearly did not understand of the process sometimes called "ROOSD" when making these comments...

I agree. One of the fundamental issues of contention results from the difference between "identifying" or "recognising" a process and "understanding" or "explaining" that process. Many people identified "ROOSD" (Or whatever we call it) Starting with Bazant in the B&Z paper. Few if any explained it and IMO fewer still strictly and rigorously distinguished that actual real event mechanism from other progressions including the column crushing scenario used by B&Z.

These explanations are primitive (and wrong) compared to what we can now verify.

Please follow my hint ( Blunt demand??). Which "explanations" do you refer to? Only the two you reference? If more which ones?

... which repeats the same deceptive memes circulating elsewhere.

I am fully aware of many wrong or insecure arguments which rely on false memes. We will never dispose of them whilst we remain vague. They need to be euthanased one by one by specific argument. And that process will be challenging to both sides as well as "middle grounders".

Why not start by picking one - it will have to be a basic foundation level issue - put it up and we will see who can "put up or shut up" if anyone will address the technical fact and stop the perennial needling and bashing of alleged truthers or anyone who dares to think and disagree.

 

[Crazy Chainsaw]

Sure - maybe - I doubt it. Respectively. But Sander is quite capable of going OT without help.

Do you agree or disagree the 8 facts I identified?

Are there any others I missed at that level of importance i.e. foundation premises? I'm not interested in minor details which are neither relevant nor significant.

Yes,

The mass shedding determines speed of the collapses, and the light weight concrete was basicly dust, floor anchors had to be epoxied in type.
Wedge in or screw in anchors could not be used.
Something is shedding mass at a very high rate to slow the collapses.

 

[Dave Rogers]

Dave let me put my position clearly on record (again ).

That hilited aspect is I think the only technical issue where I seem to have a different opinion to most of the technically proficient members posting.

Most seem to accept that the approximations are valid - or "good enough".

I am not convinced that the two main approximations are good enough. They may well be - but I would like to see the factor both recognised and validly argued.

Understood, and this is a perfectly reasonable position with which I have no issue. The point that needs to be made in response to MT is that the discussion in question was a discussion of a specific model in a specific series of papers as applied to the WTC collapses, and that discussion of other models should not have been included, not out of dishonesty, but on grounds of relevance. Therefore, his carefully constructed feelings of outrage are inappropriate.

Dave

 

[GlennB]

But what is more characteristic of the collapse is the breaking up and communition of the floor slabs... grinding themselves into finer and finer grains and more less flowing much the way gravel flows through a hopper / chute.

You've been saying this for a few days now, employing phrases like "reduced to dust and sand" and so on, and it's just plain wrong. That concrete was poured onto steel pans and had rebar embedded in it, strongly tending to hold it together. The so-called 'meteorites' are an example of the outcome and show the concrete comminuted to nothing even resembling the extent you claim. Other photos of the debris pile show concrete remains across a huge range of particle size.

In addition, comminution theory requires larger pieces to do the comminuting of smaller pieces and this becomes less probable (logarithmically so iirc) as particle size diminishes. Cube/square law and the lower likelihood of flaws (potential fracture points) in smaller particles come into it, but it's a long time since I looked at that stuff.

We've had many discussions here where Truthers point out the improbable energy required to turn that concrete to dust. They were wrong because it simply didn't happen.

 

[ozeco41]

Understood, and this is a perfectly reasonable position with which I have no issue. The point that needs to be made in response to MT is that the discussion in question was a discussion of a specific model in a specific series of papers as applied to the WTC collapses, and that discussion of other models should not have been included, not out of dishonesty, but on grounds of relevance.

I can dig the technical correct bits out of his arse-about obscure JAQing way of stirring the pot. But he is not interested in clarity of technical issues. Nor relaxing his constant implications of primacy of discovery and primacy of understanding. He is also partly correct on the memes thing BUT refuses to be specific there also.

Therefore, his carefully constructed feelings of outrage are inappropriate.

It is a common aspect of his style - all or nothing - black or white - if he finds one alleged error it disproves the lot - with zero recognition of "relevance" or "significance". I've counselled and advised him many times on a couple of forums. He explicitly denies "relevance" and "significance" as factors in logical reasoning - those two alone make discussion near impossible. I doubt it is deliberate trickery - simply a genuine poor foundation for reasoning processes.

Overall I think the discussions - both technical and behavioural could be worthwhile. But not until we can get rid of the personal commentaries and the evasive fogginess of non-specific assertions. Both sides - and maybe the middle grounders. But I've been on that theme since 2010 for this particular sector of interest.

Those later papers were all written for specific and narrowly focussed objectives against the background of Bazant's wish for a generic model.

Whether or not he (Bazant) correctly applies principles derived from approximations to specific WTC situations is a subset of - specific applications of - my general concerns about validity of approximations.

I may do the hard yards of re-reading those papers with brain in gear. But it takes effort to detect when people are subconsciously quote mining to suit their own pre-set agenda.

I used to get paid for it but been retired now for ~15 years.

 

[JSanderO]

I think it is BUT:
A) Do you or do you not agree with the 8 points of fact I identified?

B) Have I missed any other points of relevant technical fact related to the use we make of Bazant and Zhou?

I understand your position as you have stated it many times. It is not relevant to my thesis. The engineering aspects critical to the collapse are: (i) The floors failed AND (ii) removed the bracing of the outer perimeter. Plus (iii) some secondary interactions with the core. Do you agree those three assertions (i), (ii) and (iii)?

Correct - it is OT.

I agree.

 

[Crazy Chainsaw]

I think I have some clues and while I don't have a problem learning new things... I don't think this paper will add to what I am looking for in understanding the collapses. You need to dial back your "style" a bit. Thank you!

My comment was not ment as an insult JSO, but as a factual statement, not a tumbler effect,
High speed sand blaster strong enough that the intergrandualar friction will ignite and produce chemical reactions that continue in the rubble pile.
Especially with water and reactive metals like galvanized steel.

 

[ozeco41]

I agree.

Thanks Sander. That makes two (2) of us.

Should I be mischievous and assume that those not prepared to agree are de-facto disagreeing?

Lets see if M_T is game to comment because - as far as I can discern - he would assert that all of those issues of fact are true facts.

Ad we are only discussing the B&Z stuff. I may need to move onto the later papers.

 

[JSanderO]

My comment was not ment as an insult JSO, but as a factual statement, not a tumbler effect,
High speed sand blaster strong enough that the intergrandualar friction will ignite and produce chemical reactions that continue in the rubble pile.
Especially with water and reactive metals like galvanized steel.

I've been interested in learning about what might have been happening in that instant chemistry lab.... all manner of chemicals... water, lots of heat from friction and some from fire all ready burning... I don't see too much discussion of it and the collapse is almost treated like dropping pancakes... which of course is nonsense.

 

[Crazy Chainsaw]

I've been interested in learning about what might have been happening in that instant chemistry lab.... all manner of chemicals... water, lots of heat from friction and some from fire all ready burning... I don't see too much discussion of it and the collapse is almost treated like dropping pancakes... which of course is nonsense.

That's because it is so complex and hard to investigate, it takes recreating the events to understand it. You have combustion, reduction, acids, and reactive metals.

Most prefer to ignore the chemistry, and concentrate on the engineering, I believe Dr. Greening has been puzzled by the speed of the fall of the buildings as I have, it is hard to understand, how enough mass can be shed, without added energy to slow the collapses.
That energy could not come from building resistance, or air resistance, but it could come from a lot of thermal energy, heat, question is what is the source of that added heating?

 

[ozeco41]

I don't see too much discussion of it and the collapse is almost treated like dropping pancakes... which of course is nonsense.

That's because it is so complex and hard to investigate, it takes recreating the events to understand it. You have combustion, reduction, acids, and reactive metals...

Take care both of you that you are not losing "systems level" - focusing on details when the definitive factors are one or more levels higher in "system" or "taxonomic hierarchy". Model it as "Systems v sub-systems" OR "sets-subsets" or "Venn diagrams" if "taxonomy" is foreign to your way of describing. Put simply get the bits of argument properly arranged in relation to each other. And the "bits" are parts of "the next bigger picture"

The relevant level Sander is that the floors were taken out - disconnected. And that doesn't change whether the detail is shear of joist/column connectors or break-up of the floor structure provided it disconnects the perimeter columns. Disconnecting the perimeter is what counts.

The "combustion, reduction, acids, and reactive metals.." are details of means which lead to the failure of structure members in engineering physics. Again the relevant factor at the bigger picture level is that the structural member fails. Not the micro level of chemistry. Wouldn't matter if it was caused by Santa's Custard. What counts is the engineering fact that the members fail.

Most prefer to ignore the chemistry, and concentrate on the engineering,

Of course. Whether they recognise it or not that is the correct relationship - engineering higher up the ladder of importance than the chemistry. Higher level of taxonomy if we use that language to describe the structure of the logic.

I believe Dr. Greening has been puzzled by the speed of the fall of the buildings as I have, it is hard to understand, how enough mass can be shed, without added energy to slow the collapses.

It never will be easy - if in fact it is possible - to argue from the wrong end or wrong level

That energy could not come from building resistance, or air resistance, but it could come from a lot of thermal energy, heat, question is what is the source of that added heating?

what happened happened. Define the engineering mechanics first THEN you have a framework onto which you can overlay energetics - if you still need to. What is the objective? Explain the collapse? OR Micro analysis of energetics?