OOS Collapse Propagation Model

[Richard the G]

a probable translation:

In 15 seconds or so the /area of wind / volume of air within the tower was pushed out the tower and then an equal or greater volume of air came back in to replace the void left by the now missing structure.


I think Richard is trying to say that the inrushing air would be a force on the top of the falling mass.
In fact we can see the effect of the later as the smoke from the fires gets drawn down as the collapse continues. Not a particularily strong force is evident in this and I cannot envision it having much effect in driving the collapse.

Remember that the windows were 18in wide so the glass had enormous strength. If you do some calcs in how much air had to escape from the floor you get wind speeds of several hundred miles an hour.

So the wind had two main effects. the first is obvious, the walls of the tower were blown out with enough initiating force so that the tower appeared to unpeel like a banana.

The second was that the elevator shafts became big air ducts. So that why you got some explosive failures at elevator transfer floors and the upward wind will have blasted the upper floor levels causing severe damage in the upper section.

 

[Richard the G]

I would like to call this the PATCH theory.
Pressure
Assisted
Tower
Collapse
Hunch

At least it is more honest than ROOSD

 

[Major_Tom]

Below is another PhD thesis on the subject of progressive collapse.



A Method to Assess the Progressive Collapse Vulnerability of Frame Structures

Department of Architecture, Civil Engineering and Environmental Sciences
University of Braunschweig

by Francesco Barni

linked here.




He begins by describing various examples of progressive collapse in chapter 1:



Chapter 1 - What is Progressive Collapse

1.1 Definition of Progressive Collapse

1.2 Opposing Progressive Collapse

1.3 What prompts a Collapse

1.4 Case studies

1.4.1 The Ronan Point Tower

1.4.2 The Hyatt Regency Walkways

1.4.3 The Alfred P. Murrah Federal Building

1.4.4 The World Trade Center

1.4.4.1 Buildings 1 and 2 of the World Trade Center

1.4.4.2 Building 7 of the World Trade Center

1.4.5 The Eads Bridge

1.5 Summary and comments




Each case is described in detail, but when it comes to a description of the WTC1 and 2 collapse progressions, the author describes them by using only one simplified meme made popular by the NIST:

"Global collapse ensued."


Even though the dissertation was written in 2011, the only justification to explain this meme is the BZ argument, written in 2001. This meme, global collapse ensued', was also the only comment on the specifics of the WTC1 and 2 collapse progression modes available in the entire NIST report.




There isn't a single sentence within the dissertation that suggests the author was aware that the mechanism sometimes called 'ROOSD' occurred in WTC1 or 2.

 

[JSanderO]

There isn't a single sentence within the dissertation that suggests the author was aware that the mechanism sometimes called 'ROOSD' occurred in WTC1 or 2.

Perhaps a conclusion of what you report if true... might be:

the global collapse mechanism is of no interest to these engineers and by extension the entire engineering community because (maybe) once a system reaches a point of no return how it completely fails may be of no practical consequence. Unless there are economical/feasible means to have prevented it and save lives.

or

these engineers are actually lazy and would rather play with equations than analyze the visual evidence of the event / collapse

or

they are all too lazy or uninterested to follow the independent researchers such thinking they are not worthy of consideration

or

They are aware of the mechanisms have read (stealthy) the internet and are too embarrassed to admit they missed the proper explanations

or

the ROOSD mechanism has consequences related to design decisions

or

a combination of the above

or

none of the above and they thing they did stellar work in describing the event and never looked back.

 

[DGM]

Perhaps a conclusion of what you report if true... might be:

Or.....

Engineers understand the use of a model that does not exactly reflect the events of a "one off" (three actually)design but reflects the forces involved in one more robust (inline with conventional design).

This is not all about the WTC Towers.

 

[Major_Tom]

Consider the following paper written in 2007:



Typology of progressive collapse

by Uwe Starossek
Structural Analysis and Steel Structures Institute, Hamburg University of Technology (TUHH)
Denickestr. 17, 21073 Hamburg, Germany

The paper is linked here.



The abstract, bolding is mine:

"Abstract

A typology and classification of progressive collapse of structures is developed that is founded on a study of the various underlying mechanisms of collapse. Six different types and four classes are discerned, the characteristic features of each category are described and compared, and a terminology is suggested. On this basis, the theoretical treatment of progressive collapse and the development of countermeasures are facilitated because they differ for different types of collapse. Some conclusions drawn here concern analogies that should be pursued further, collapse-promoting features, and possible countermeasures."


Many of us are aware the underlying mechanism of the WTC1 and 2 collapse propagation is what I call ROOSD.


The author describes the underlying mechanism of the WTC1 and 2 collapse progressions like this:


"2. Types of progressive collapse

2.1 Pancake-type collapse

This type is exemplified by the collapse of the World Trade Center (WTC) towers. The impact of the airplanes and the subsequent fires initiated local failures in the areas of impact. The ensuing loss in vertical bearing capacity was limited to a few stories but extended over the entire cross section of the respective tower [1, 2]. The upper part of the structure started to move downwards and accumulated kinetic energy. The subsequent collision with the lower part of the structure, which was still intact, caused large impact forces which were far beyond the reserve capacities of the structure. This in turn led to the complete loss of vertical bearing capacity in the area of impact. Failure progressed in the same manner and led to a total collapse.
A pancake-type collapse exhibits the following features:

- initial failure of vertical load-bearing elements
- partial or complete separation and fall, in a vertical rigid-body motion, of components"



This is typical of how the WTC collapses are described within much of the literature I have come across. There is no evidence the author can specify the mechanism of collapse progression with any more detail than this general description provides.

 

[DGM]

This is typical of how the WTC collapses are described within much of the literature I have come across. There is no evidence the author can specify the mechanism of collapse progression with any more detail than this general description provides.

Is your problem the lack of visual detail? The description is not wrong.

 

[JSanderO]

Is your problem the lack of visual detail? The description is not wrong.

not really accurate... what seems to have collided was the floors (in increasingly small chunks) and the floor contents.
NO COLUMNS OR STRUCTURE WAS IMPACTING ON STRUCTURE BELOW IN THE *GLOBAL PHASE* OR THE PROGRESSIVE COLLAPSE... POST INITIATION OR AT *RELEASE*.

 

[DGM]

not really accurate... what seems to have collided was the floors (in increasingly small chunks) and the floor contents.
NO COLUMNS OR STRUCTURE WAS IMPACTING ON STRUCTURE BELOW IN THE *GLOBAL PHASE* OR THE PROGRESSIVE COLLAPSE... POST INITIATION OR AT *RELEASE*.

Not wrong. Lacks detail, that's it.

- initial failure of vertical load-bearing elements
- partial or complete separation and fall, in a vertical rigid-body motion, of components"

Do you agree?

 

[Reactor drone]

Each case is described in detail, but when it comes to a description of the WTC1 and 2 collapse progressions, the author describes them by using only one simplified meme made popular by the NIST:

"Global collapse ensued."


Even though the dissertation was written in 2011, the only justification to explain this meme is the BZ argument, written in 2001. This meme, global collapse ensued', was also the only comment on the specifics of the WTC1 and 2 collapse progression modes available in the entire NIST report.

Global collapse did follow the collapse initiation. Any method to prevent a global collapse will involve preventing collapse initiation from taking place rather than arresting an ongoing collapse so detailed examinations of the collapse progression would seem unnecessary in that paper.

There isn't a single sentence within the dissertation that suggests the author was aware that the mechanism sometimes called 'ROOSD' occurred in WTC1 or 2.

Perhaps it's because you're the only one pushing for inclusion of descriptions of the ROOSD process but you're completely unable to form a cogent argument as to why they should be included.

 

[LSSBB]

Global collapse did follow the collapse initiation. Any method to prevent a global collapse will involve preventing collapse initiation from taking place rather than arresting an ongoing collapse so detailed examinations of the collapse progression would seem unnecessary in that paper.





Perhaps it's because you're the only one pushing for inclusion of descriptions of the ROOSD process but you're completely unable to form a cogent argument as to why they should be included.

Is Tom's theory even published? I don't see how it would even be on an academic's radar. Does Tom think they do their research by Google? This isn't an undergraduate theme paper he references, and I doubt a serious academic on this subject would want to wade through 9/11 Google fu.

 

[Oystein]

...
There isn't a single sentence within the dissertation that suggests the author was aware that the mechanism sometimes called 'ROOSD' occurred in WTC1 or 2.

Which academic journal that a doctoral student of civil engineering can be supposed to have on his radar has published an article that describes ROOSD?

In which journal have YOU published this mechanism?

 

[Major_Tom]

Perhaps a conclusion of what you report if true... might be:

the global collapse mechanism is of no interest to these engineers and by extension the entire engineering community because (maybe) once a system reaches a point of no return how it completely fails may be of no practical consequence. Unless there are economical/feasible means to have prevented it and save lives.

or

these engineers are actually lazy and would rather play with equations than analyze the visual evidence of the event / collapse

or

they are all too lazy or uninterested to follow the independent researchers such thinking they are not worthy of consideration

or

They are aware of the mechanisms have read (stealthy) the internet and are too embarrassed to admit they missed the proper explanations

or

the ROOSD mechanism has consequences related to design decisions

or

a combination of the above

or

none of the above and they thing they did stellar work in describing the event and never looked back.

I do not think these people are stupid or lazy. I don't think Bazant is stupid, or Seffen, or Eagar or Musso.

I think that each was working under limitations of observation, measurement, and perception at the time they wrote their dissertations or papers. They were each responding to the environment in which they lived and worked and their papers were adding to that same environment.

It is obvious they were limited in what they knew and that their readers, peer reviewers and faculty advisers were likewise limited.

It isn't just them. It is the environment in which they were writing. It was a collective breakdown of the process of feedback between author and publisher, author and reader, author and reviewer.

The Journal of Engineering Mechanics was the publisher of 5 of the mentioned papers. There was a very permissive environment within JEM that allowed these misrepresentations to flourish unchecked (for years).

 

[Major_Tom]

I wonder what the point is. His OOS (or whatever) is not wrong. It's been the accepted explanation of the progression since 2001.

Which academic journal that a doctoral student of civil engineering can be supposed to have on his radar has published an article that describes ROOSD?

Is Tom's theory even published? I don't see how it would even be on an academic's radar.

This is what physicist David Bohm referred to as 'sustained incoherence.'


When creating superficial one-liners and memes within this thread the regular JREF posters may want to coordinate the memes so as to not contradict one another.

Is the group going to go with the 'everybody knows the accepted explanation' meme or the 'how could the authors have known' meme?

 

[beachnut]

This is what physicist David Bohm referred to as 'sustained incoherence.'
...

Your book was called "sustained incoherence"? When did he do that? I have to agree.

Have you decided if your claim the "gravity collapse was an illusion", is still true, or what?

What about the stuff you can't see due to dust and debris, how does your "what you see" model with no math or physics, explain what we can't see? How does that work?

Are you still a CD believer, or do you think the collapse was a result of aircraft impacts and fires? Can you debunk anything other than this constant projecting BS of post which mean nothing?

Why can't you guys debunk the lies posted at 911 Forum place with the "just plain idiots" thread - a cracker jack thread.

 

[Seymour Butz]

Global collapse did follow the collapse initiation. Any method to prevent a global collapse will involve preventing collapse initiation from taking place rather than arresting an ongoing collapse so detailed examinations of the collapse progression would seem unnecessary

^^^

This is why MT gets such apathy. Nothing he has done will ever be used to prevent a progressive collapse. He has been spinning his wheels for years.

 

[Major_Tom]

Dave Rogers, PhD physics, to a poster called bio in the first 8 pages of this thread:

You were claiming that the top block was smashed into rubble; now you're saying that 'a big part' was smashed into rubble, and that you only saw the first two seconds. At the end of that two seconds, there was still a large part of the upper block intact, and you don't know what happened to it after that because you couldn't see it. So your observation - now you've admitted to what you actually observed, rather than what you initially claimed you observed - is in fact completely consistent with an initial limited amount of crush-up, followed by primarily crush-down.

Without some kind of modelling the only rational assumption would be that we don't know whether the crush-up of the upper block continued, and anything more would be a guess. Since the only case that's been analysed indicates that crush-up is expected to arrest, then it's reasonable to assume that that was the case in reality.

These comments were considered perfectly reasonable by other JREF regulars at the time they were made in 2010, nine years after the actual collapses.


I don't think Dave is dumb or lazy.

I think he was working under limitations of observation, measurement, and perception at the time he made the comment.

It is obvious he was limited in what he knew and that his fellow posters were likewise limited.

It isn't just him, obviously. It is the environment in which he was writing. It was a collective breakdown of the process of feedback within the JREF environment and among fellow posters.

There was a very permissive environment within JREF that allowed these misrepresentations to flourish unchecked (for years).

 

[beachnut]

...
There was a very permissive environment within JREF that allowed these misrepresentations to flourish unchecked (for years).

What misrepresentations? Does this mean you stand by your, "gravity collapse was an illusion" BS? Why does 911 Forums let lies about 911 go "unchecked"?

Very permissive, no plain just permissive, or smart permissive, ...

Your model is incomplete, you left out what happened behind the dust, behind the debris. How will you complete it? Did you have Ground Penetrating RADAR video so you could see the interior collapse propagation model??? ...

Can you list the misrepresentations? Or will they be like the "gravity collapse is an illusion" BS.

How will did your model debunk 911 truth claims? CD? Thermite? High explosives? Any progress on the debunking side of 911, the real truth side?

 

[tsig]

This is what physicist David Bohm referred to as 'sustained incoherence.'


When creating superficial one-liners and memes within this thread the regular JREF posters may want to coordinate the memes so as to not contradict one another.

Is the group going to go with the 'everybody knows the accepted explanation' meme or the 'how could the authors have known' meme?

I'll go with the Who Cares? meme.

 

[rwguinn]

I'm sticking with "it's six of one and 3 pairs of the otber"