OOS Collapse Propagation Model

[ozeco41]

Oz, JSO, I envision Euler column buckling taking effect at column splices. This because that is the stiffest point and stress builds there

I've been letting the description as "Euler Buckling" pass - whether or not it is technically correct for some columns there were multiple other effects knocking core columns over. The column splices were the weakest point - look to the failure patterns Major_Tom has identified in his mammoth effort at "what bit went where". It's certain IMO that 99% of those failures were in bending moment as Newtons Bit has already alluded.

But - lifting our perspective from details of engineering pedantry. The key issue IMO for the core is that there was a readily available mechanism to strip down the horizontal beams of the core failing them in shear at the beam<>column connection. That mechanism for the core is directly analogous to ROOSD floor stripping but no where near as clearly obvious and the details would be a lot more confused.

Again moving above the detail - however it happened in detail - that process of "beams stripped off" then left the columns at the mercy of whatever other tip over/buckle/push sideways mechanism were available. The visual evidence of the spires is IMO persuasive argument that "beams stripped off" was the dominant mechanism which removed the bracing and set the columns up to fail. Whatever the final cause of failure.

Add that "core strip down" to "ROOSD" and "Perimeter Peel Off" and it completes the three main mechanisms of the progression stage. Which I regard as the current hypothesis irrespective of whether it was Major_Tom who assigned the acronym "ROOSD" OR whoever wants to claim they were first to distinguish that mechanism from Bazant's abstract model.

 

[rwguinn]

...snip of technically accurate and many-times stated descriptions...

Add that "core strip down" to "ROOSD" and "Perimeter Peel Off" and it completes the three main mechanisms of the progression stage. Which I regard as the current hypothesis irrespective of whether it was Major_Tom who assigned the acronym "ROOSD" OR whoever wants to claim they were first to distinguish that mechanism from Bazant's abstract model.

My complaint is that MT has claimed as his very own, unique mechanism, that which has been stated and described in painstakingly accurate detail from 2001 until now by engineers, physicists, and intelligent lay persons.
The fact that it is reasonably correct and the probable mechanism finally arrived at by a truther makes me happy.
But i don't like those who steal work and claim it as their own, especially for profit.

 

[WilliamSeger]

Add that "core strip down" to "ROOSD" and "Perimeter Peel Off" and it completes the three main mechanisms of the progression stage. Which I regard as the current hypothesis irrespective of whether it was Major_Tom who assigned the acronym "ROOSD" OR whoever wants to claim they were first to distinguish that mechanism from Bazant's abstract model.

I believe Bazant & Zhou were the first to make that distinction:

The main purpose of the present analysis is to prove that the whole tower must have collapsed if the fire destroyed the load capacity of the majority of columns of a single floor. This purpose justifies the optimistic simplifying assumptions regarding survival made at the outset, which include unlimited plastic ductility (i.e., absence of fracture), uniform distribution of impact forces among the columns, disregard of various complicating details (e.g., the possibility that the failures of floor-column connections and of core columns preceded the column and tube failure, or that the upper tube got wedged inside the lower tube), etc. If the tower is found to fail under these very optimistic assumptions, it will certainly be found to fail when all the detailed mechanisms are analyzed, especially since there are order-of-magnitude differences between the dynamic loads and the structural resistance.

 

[JSanderO]

My complaint is that MT has claimed as his very own, unique mechanism, that which has been stated and described in painstakingly accurate detail from 2001 until now by engineers, physicists, and intelligent lay persons.
The fact that it is reasonably correct and the probable mechanism finally arrived at by a truther makes me happy.
But i don't like those who steal work and claim it as their own, especially for profit.

This sounds like rubbish to me. Where is the evidence that anyone stole "work" and claimed "it" as their own?

Perhaps you want to cite the "work" where the "same thing" as what is referred to as ROOSD was set forth... in making your assertion of "stealing".

 

[ozeco41]

I believe Bazant & Zhou were the first to make that distinction:

Correct. B&Z was explicit. My reference was to folks posting on this and other forums where I witnessed lots of confusion as to the scope of Bazant's works.

That confusion and the personal commentary was evident at the start of this thread. We even had a full separate thread to clarify the distinctions and boundary between abstract models and "real event".

I was surprised to see statements claiming or implying that such confusion never existed but...

And my position still seems to be unclear to some. Partly because I started behind the eight ball - I wasn't expecting denial of the confusion that existed 2009-10. OK so I'm trying to deal with two aspects of this discussion:

A) I refer SPECIFICALLY the mix and match confusions when people mixed bits of Bazant with real event. "Missing Jolt" being the truther side classic but many from debunker side - e.g. Bazant model energy based calculations which sought to verify the collapse timings of the "real event" using the Bazant "columns in line" model.

B) I SPECIFICALLY do NOT mean the fact that many people had recognised the mechanism of material falling in the open office spaces shearing the floor trusses. I understand and agree that many of us saw that factor early.

So what if several members disagree with me on the historic aspect of confusions affecting forum discussions?

I see no point in arguing about whether there was or was not confusion. NOR in pursuing the strong interpersonal aggression issues. Let's move on.

For the record of those not aware Major_Tom is no fan of mine. Most times I COMMEND the technical component of his work he comments about it on another forum in a special thread dedicated to character assassination of yours truly.

I ignore those aspects and I am suggesting that in this thread on this forum we should isolate objective issues of technical fact from discussion or allusion to personal aspects.

IMO Two of the three or four key aspects are:

1) Is the "fall of material down the open office space tube" a valid description of the leading mechanism of Twin Towers progression stage collapse?

Status:
I say it is. I see no-one here disagreeing with that technical fact EXCEPT beachnut and tfk in the other thread which started this resurgent discussion.

2) Can Bazant limit case assumptions be mixed into a "real event" analysis? (Note: "mixed into" NOT "put a boundary fence around.")

Status:
I say no. I see no-one saying that they can be mixed in. Equally I see no-one explicitly agreeing that there cannot be "mix and match". Most are not commenting on that aspect or making comments which are ambiguous.

I'm suggesting move forward to discuss or clarify the technical aspects and set aside all the personal stuff OR technical conclusions based on personal dislikes.

If anyone wants to take on Major_Toms "style" of self aggrandising arrogance - then I suggest it should be in a separate thread.

The validity of the two technical aspects does not depend either way on M_T's "style".

 

[Newtons Bit]

My complaint is that MT has claimed as his very own, unique mechanism, that which has been stated and described in painstakingly accurate detail from 2001 until now by engineers, physicists, and intelligent lay persons.
The fact that it is reasonably correct and the probable mechanism finally arrived at by a truther makes me happy.
But i don't like those who steal work and claim it as their own, especially for profit.

In addition to that, which I fully agree with, the name itself grates on me:
Runaway Open Office Space Destruction.

An "Open Office Space" is an architectural feature that allows tenants to create configurable spaces for their own needs. All it means is that there is a minimum amount of full height partition walls (for bathrooms, elevators, etc) and a tenant can then choose to erect their own partition walls or leave the space open and lay out rows of workstations or cubicles. The spacing of columns, while generally preferred to be large in open plans, can still be substantially closer than what the WTC floors spanned.

By stating that "ROOSD" is the mechanism, vs the industry standard term "progressive collapse" I'm falsely led to believe that Major_Tom is placing an emphasis on the lack partition walls. And as you and I both know, 26 gauge metal studs fastened to the floor below and to the floor above with a deflection track aren't going to contribute any collapse resistance. Based on Major_Toms writing, I'm pretty sure not what he's referring to either.

But the hubris of claiming to be an expert, and that all the other experts are actually wrong, while being unable to create an acronym that doesn't lead actual professional astray, really bothers me. It makes it hard to take any of his claims seriously.

 

[beachnut]

This sounds like rubbish to me. Where is the evidence that anyone stole "work" and claimed "it" as their own?

Perhaps you want to cite the "work" where the "same thing" as what is referred to as ROOSD was set forth... in making your assertion of "stealing".

The WTC towers system, shell, core, floors, dictate how it collapses; the structure of the WTC towers explain in detail how it collapses. Rubbish, the official story rubbish to many based on ignorance and shallow research. Even your self once said "rubbish", or as you said, "I am not satisfied with the explanation given. The explanation raises more questions than it answers." I think this satisfaction problem is based on lack of research.

Bazant talked about the same thing, but skipped the dumb down acronym BS. Have to read his papers, and there is math, and models, which 911 truth can't comprehend, and they also have a problem with reading comprehension.

Bazant summed it up in one or two paragraphs (or was it a sentence), Robertson summed it up in one sentence (or so), MT took years and ended up with no rational conclusion. Even NIST summed up OOS, 911 truth missed it.

 

[Major_Tom]

My reference was to folks posting on this and other forums where I witnessed lots of confusion as to the scope of Bazant's works.

That confusion and the personal commentary was evident at the start of this thread. We even had a full separate thread to clarify the distinctions and boundary between abstract models and "real event".

I was surprised to see statements claiming or implying that such confusion never existed but...

These threads prove beyond doubt that within this environment confusion is the rule, not the exception.

You mention 'lots of confusion'. A challenge for you...

1) Please point to a single discussion in any forum on this subject where confusion is the exception, not the rule.

2) Please link to a single exchange within this thread or this forum where the participants are capable of accurately distinguishing between the arguments made in BZ (2002) and the arguments made in Bazant's latter papers on the subject from 2007 onward.

I see no point in arguing about whether there was or was not confusion.

Confusion and historic revisionism are what I am studying. This is an excellent opportunity to study cognition and human perception. I am certainly not participating here for the quality technical arguments.

For the record of those not aware Major_Tom is no fan of mine.

I don't look at you, Ozeco. I look at your arguments.

You seem to be the only regular poster here that recognizes a contradiction between Bazant's latter papers and the OOS propagation model.

No other regular poster here seems to be able to admit there is a contradiction between Bazant's latter papers and statements about 'crush down, then crush up' and the ROOSD concept at all.

TFK and Beachnut are not exceptions. Confusion and false certainly are the rule, not the exception. No need to argue about it. It is documented.

 

[JSanderO]

In addition to that, which I fully agree with, the name itself grates on me:
Runaway Open Office Space Destruction.

An "Open Office Space" is an architectural feature that allows tenants to create configurable spaces for their own needs. All it means is that there is a minimum amount of full height partition walls (for bathrooms, elevators, etc) and a tenant can then choose to erect their own partition walls or leave the space open and lay out rows of workstations or cubicles. The spacing of columns, while generally preferred to be large in open plans, can still be substantially closer than what the WTC floors spanned.

By stating that "ROOSD" is the mechanism, vs the industry standard term "progressive collapse" I'm falsely led to believe that Major_Tom is placing an emphasis on the lack partition walls. And as you and I both know, 26 gauge metal studs fastened to the floor below and to the floor above with a deflection track aren't going to contribute any collapse resistance. Based on Major_Toms writing, I'm pretty sure not what he's referring to either.

But the hubris of claiming to be an expert, and that all the other experts are actually wrong, while being unable to create an acronym that doesn't lead actual professional astray, really bothers me. It makes it hard to take any of his claims seriously.

This is a rather silly response and parsing of words. It sounds more like you have a bone to pick with Tom than with his work.

The twin towers design at the time was very unique in that the engineers removed the interior columns... placing them in a structure facade creating column free rentable space outside the core. Any interior partitions or office landscape (which originated at the time) played no role in structural integrity of the building and were simply superimposed dead loads.

The acronym is fine for anyone who can understand how this "hull and core" concept differs from a standard high rise frame with a grid of columns.

A collapse in a standard frame would likely be prevented from propagating laterally and be confined with the bay where it occurred. In the WTC design without bays to limit the lateral propagation the collapse is prone to spread and involve the entire column free floor area outside the core. I believe this is a key element of ROOSD... and something that the term "progression floor collapse" does not reflect.

I don't know that Tom refers to himself as an expert any more than any other poster who advances their work / analysis of what may have occurred in the destruction of the towers.

Right or wrong? No one... including you as far as I am aware... has shown where any other "experts" detailed the mechanisms of the collapse phase as Tom has. Others including yours truly deduced this process independently... I called it a vertical avalanche... but who cares? And the acronym is handy.

As Ozzie notes the Bazant work does not reflect the real world building movements which Tom has used to derive his ROOSD and so I find that ROOSD by whatever name one wants to use is more useful and more accurate that Mr B's papers.

Frankly I don't know if Tom is a "truther" or not and it hardly matters if what he describes is accurate. ROOSD makes no claim as to the how the threshold mass was created to drive the ROOSD process. It could have been dropping a bunch of A1A Abrams tanks on the roof of the towers... for all I care... but once that mass was "freed" from the structure it was what destroyed the floors... which were the bracing for the facade and the core which as Ozzie notes was stripped of its bracing as well... leaving the remaining columns... not crushed but too unstable to stand... and so they "collapsed" as well.

Too many JREFers come off as close minded and in denial because of the "messenger" which prevents them from acknowledging the validity of the message.

If the ROOSD process by any name was described in detail by other experts back in 2002 or there abouts... please provide references.

What I see is a crisis in critical thinking skills... and refusing to accept something because you don't like who said it.

 

[pgimeno]

This sounds like rubbish to me. Where is the evidence that anyone stole "work" and claimed "it" as their own?

Perhaps you want to cite the "work" where the "same thing" as what is referred to as ROOSD was set forth... in making your assertion of "stealing".

Probably rediscovered rather than stolen.

This is what FEMA said back in 2002 about the collapses. I've posted it a number of times already (in this very thread, p.20, message #761 for one) but here it is again:

2.2.1.5 Progression of Collapse

Construction of WTC 1 resulted in the storage of more than 4x10¹¹ joules of potential energy over the 1,368-foot height of the structure. Of this, approximately 8x10⁹ joules of potential energy were stored in the upper part of the structure, above the impact floors, relative to the lowest point of impact. Once collapse initiated, much of this potential energy was rapidly converted into kinetic energy. As the large mass of the collapsing floors above accelerated and impacted on the floors below, it caused an immediate progressive series of floor failures, punching each in turn onto the floor below, accelerating as the sequence progressed. As the floors collapsed, this left tall freestanding portions of the exterior wall and possibly central core columns. As the unsupported height of these freestanding exterior wall elements increased, they buckled at the bolted column splice connections, and also collapsed. Perimeter walls of the building seem to have peeled off and fallen directly away from the building face, while portions of the core fell in a somewhat random manner. The perimeter walls broke apart at the bolted connections, allowing individual prefabricated units that formed the wall or, in some cases, large assemblies of these units to fall to the street and onto neighboring buildings below.

Review of videotape recordings of the collapse taken from various angles indicates that the transmission tower on top of the structure began to move downward and laterally slightly before movement was evident at the exterior wall. This suggests that collapse began with one or more failures in the central core area of the building. This is consistent with the observations of debris patterns from the 91st floor, previously discussed. This is also supported by preliminary evaluation of the load carrying capacity of these columns, discussed in more detail in Section 2.2.2.2. The core columns were not designed to resist wind loads and, therefore, had less reserve capacity than perimeter columns. As some exterior and core columns were damaged by the aircraft impact, the outrigger trusses at the top of the building shifted additional loads to the remaining core columns, further eroding the available factor of safety. This would have been particularly significant in the upper portion of the damaged building. In this region, the original design load for the core columns was less than at lower floors, and the column sections were relatively light. The increased stresses caused by the aircraft impact could easily have brought several of these columns close to their ultimate capacity, so that relatively little additional effects due to fire would have been required to initiate the collapse. Once movement began, the entire portion of the building above the area of impact fell in a unit, pushing a cushion of air below it. As this cushion of air pushed through the impact area, the fires were fed by new oxygen and pushed outward, creating the illusion of a secondary explosion.
​

(FEMA 403, chapter 2, p. 2-27)

 

[DGM]

This is from the PBS special that aired on April 30, 2002.

NARRATOR: These pictures show that the South Tower fell away from the impact wall and toward the side where the fire had concentrated. To the team, this suggested a particular mechanism for the collapse, which the video helped confirm.

The plane slammed along the eastern wall, starting a fierce fire in the northeast corner and severely damaging many of the steel columns in this area. The heat of the fire would have softened both the floor trusses and the outer columns they were attached to. When the steel became weak, the trusses would have collapsed. And without the trusses to keep them rigidly in place, the columns would have bent outward and then failed.

CHARLES THORNTON: As you start to lose the lateral support due to the floors, the exterior just crumples like a piece of paper. Or if you took a sheet of cardboard and you put some weight on it and you take out the lateral supports it will just bow right out.

NARRATOR: This footage shows the process in action. A line of columns in the outer skeleton snaps. The top of the building then lurches outwards and falls. As it does so, it dislodges many more floor trusses. Once the trusses fail, the floors they were holding cascade down with a force too great to be withstood. The result is what's called a "progressive collapse," as each floor pancakes down onto the one below.

http://www.pbs.org/wgbh/nova/transcripts/2907_wtc.html

 

[jaydeehess]

I've been letting the description as "Euler Buckling" pass - whether or not it is technically correct for some columns there were multiple other effects knocking core columns over. The column splices were the weakest point - ....l.

"Euler" style buckling only as in being a failure mode only in the manner of being due forces resulting from long unbraced length. That it snaps bolted connections rather than buckles continuous steel columns sets it apay vrt.

Yes, lateral smacking upside the connections by very large objects would be very different.

 

[beachnut]

...
Too many JREFers come off as close minded and in denial because of the "messenger" which prevents them from acknowledging the validity of the message.
.. .

Too many JREFers are real engineers, and know BS when they see it. You saw BS and joined it. You woke up, and now you are JREF too, so attack yourself, reflect and project. Now you like BS again. Cool, the circle of woo

 

[jaydeehess]

Probably rediscovered rather than stolen.

This is what FEMA said back in 2002 about the collapses. I've posted it a number of times already (in this very thread, p.20, message #761 for one) but here it is again:

2.2.1.5 Progression of Collapse

Construction of WTC 1 resulted in the storage of more than 4x10¹¹ joules of potential energy over the 1,368-foot height of the structure. Of this, approximately 8x10⁹ joules of potential energy were stored in the upper part of the structure, above the impact floors, relative to the lowest point of impact. Once collapse initiated, much of this potential energy was rapidly converted into kinetic energy. As the large mass of the collapsing floors above accelerated and impacted on the floors below, it caused an immediate progressive series of floor failures, punching each in turn onto the floor below, accelerating as the sequence progressed. As the floors collapsed, this left tall freestanding portions of the exterior wall and possibly central core columns. As the unsupported height of these freestanding exterior wall elements increased, they buckled at the bolted column splice connections, and also collapsed. Perimeter walls of the building seem to have peeled off and fallen directly away from the building face, while portions of the core fell in a somewhat random manner. The perimeter walls broke apart at the bolted connections, allowing individual prefabricated units that formed the wall or, in some cases, large assemblies of these units to fall to the street and onto neighboring buildings below.

Review of videotape recordings of the collapse taken from various angles indicates that the transmission tower on top of the structure began to move downward and laterally slightly before movement was evident at the exterior wall. This suggests that collapse began with one or more failures in the central core area of the building. This is consistent with the observations of debris patterns from the 91st floor, previously discussed. This is also supported by preliminary evaluation of the load carrying capacity of these columns, discussed in more detail in Section 2.2.2.2. The core columns were not designed to resist wind loads and, therefore, had less reserve capacity than perimeter columns. As some exterior and core columns were damaged by the aircraft impact, the outrigger trusses at the top of the building shifted additional loads to the remaining core columns, further eroding the available factor of safety. This would have been particularly significant in the upper portion of the damaged building. In this region, the original design load for the core columns was less than at lower floors, and the column sections were relatively light. The increased stresses caused by the aircraft impact could easily have brought several of these columns close to their ultimate capacity, so that relatively little additional effects due to fire would have been required to initiate the collapse. Once movement began, the entire portion of the building above the area of impact fell in a unit, pushing a cushion of air below it. As this cushion of air pushed through the impact area, the fires were fed by new oxygen and pushed outward, creating the illusion of a secondary explosion.
​

(FEMA 403, chapter 2, p. 2-27)

Amazingly, this sounds very much like what NIST summarized in its FAQ page about the collapses.

Everything old is new again,,, everybody sing along now

http://www.metrolyrics.com/everything-old-is-new-again-lyrics-peter-allen.html

Or for those of a more Christian bent;
Ecclesiastes 1:9
What has been is what will be,
and what has been done is what will be done,
and there is nothing new under the sun.

 

[JSanderO]

Too many JREFers are real engineers, and know BS when they see it. You saw BS and joined it. You woke up, and now you are JREF too, so attack yourself, reflect and project. Now you like BS again. Cool, the circle of woo

BS is BS no matter who spews it...

 

[DGM]

BS is BS no matter who spews it...

True.

Any comments on the early collapse descriptions posted? Did you watch the NOVA episode I quoted? I saw this when it first came out. I saw no real serious problems with their work.

 

[jaydeehess]

True.

Any comments on the early collapse descriptions posted? Did you watch the NOVA episode I quoted? I saw this when it first came out. I saw no real serious problems with their work.

The only bugaboo I have is the use of the term "pancake". It incorrectly implies that floors collapsed simultaneously across the entire area of each floor. There is little chance that happened at any moment through the entire collapse, its 1D thinking, an approximation at best.

 

[DGM]

The only bugaboo I have is the use of the term "pancake". It incorrectly implies that floors collapsed simultaneously across the entire area of each floor. There is little chance that happened at any moment through the entire collapse, its 1D thinking, an approximation at best.

It's really not that far off once things got going. Don't forget, this was early on (2002).

 

[Newtons Bit]

The only bugaboo I have is the use of the term "pancake". It incorrectly implies that floors collapsed simultaneously across the entire area of each floor. There is little chance that happened at any moment through the entire collapse, its 1D thinking, an approximation at best.

I think you're attributing the "pancake model" that FEMA came up with to describe collapse initiation with "pancake" as a term to describe collapse progression. It's two different things.

 

[ozeco41]

@JSanderO

One outstanding post Sander - my congratulations. Just a few comments on highlights.

This is a rather silly response and parsing of words. It sounds more like you have a bone to pick with Tom than with his work...

Which is precisely what my post identified. Lets discuss the technical topic and stop attacking the person.

Let's discuss the simple technical fact that he was right on two key points.

And doubly lets stop playing truther style debating tricks from the debunker side to falsely score points against the person - not the topic.

The twin towers design at the time was very unique in that the engineers removed the interior columns...

Exactly. And that is why Newtons Bit's false generalisation trick is so obnoxious. Some of us are trying to discuss the specific progression which occurred at WTC on 9/11 - and deliberately trying to make it simply another "progression with no differences" is a transparent bit of debate trickery. Even more obnoxious coming from an engineer on the debunker side.

The acronym is fine for anyone who can understand how this "hull and core" concept differs from a standard high rise frame with a grid of columns.

Yes. and the number of engineers implying that they cannot tell the difference OR do not need to distinguish it from all other progressions is...."interesting"^*...to me ... and I've managed a lot of technically narrow focussed engineers in my career.

I believe this is a key element of ROOSD... and something that the term "progression floor collapse" does not reflect.....

Stop right there. WTC "Twin Towers" progression was different. And to see engineers subordinating professional standards to their desire to attack M_T is disgusting. I don't agree with M_T's style or his persistent use of false logic. I've told him so and explained why in exquisite details many times on at least two forums. BUT the topic here is a technical one about collapse mechanisms. And issues of his style do not change the fact that he is right on two key claims relevant here. Nor does his style change the fact that a few of us may have got both those key claims right also. AND that a few more of us probably did get ONE of them right from the start of our involvement.

I don't know that Tom refers to himself as an expert any more than any other poster who advances their work / analysis of what may have occurred in the destruction of the towers.

disagree there Sander - BUT I have no intention of being dragged into discussing M_T's style in this thread.

Right or wrong? No one... including you as far as I am aware... has shown where any other "experts" detailed the mechanisms of the collapse phase as Tom has.

TRUE and very hard for many to argue honestly because of their history of criticising M_T's research of details. They cannot argue "didn't do it" when many of them are on record arguing "it is a waste of time". Hoist by their own petards.

Others including yours truly deduced this process independently... I called it a vertical avalanche... but who cares? And the acronym is handy.

Agreed - The WTC specific mechanism of collapse progression - which is one specific example of "progression" - did not have a name. M_T gave it one (femr2 if we want to be pedantic) I'm on record as being envious that I didn't give it a name. But Newton's implied claim that it isn't different and doesn't need a name ....should not need counter comment^*.

As Ozzie notes the Bazant work does not reflect the real world building movements which Tom has used to derive his ROOSD and so I find that ROOSD by whatever name one wants to use is more useful and more accurate that Mr B's papers.

Precisely and both those points should not need saying - but look at how many members are evading them. Avoiding commitment????

Here - let me put the two issues in a nutshell:
A) ROOSD is merely a label for an explanation of Twin Towers collapse progression which many of us subscribe to and which describes what really happened;
B) Bazant's papers - including the limit case model of B&Z - do not describe what really happened.

Frankly I don't know if Tom is a "truther" or not and it hardly matters if what he describes is accurate.

There is nothing pro-truther in his OP for this thread or AFAICS in posts through the thread. So what? We should be addressing the arguments made NOT evading arguments because we simply want to attack the character.

ROOSD makes no claim as to the how the threshold mass was created to drive the ROOSD process. It could have been dropping a bunch of A1A Abrams tanks on the roof of the towers... for all I care... but once that mass was "freed" from the structure it was what destroyed the floors... which were the bracing for the facade and the core which as Ozzie notes was stripped of its bracing as well... leaving the remaining columns... not crushed but too unstable to stand... and so they "collapsed" as well.

Yes.

Too many JREFers come off as close minded and in denial because of the "messenger" which prevents them from acknowledging the validity of the message.

And it is about time we dropped that habit and started to focus on the objective facts and arguments.

If the ROOSD process by any name was described in detail by other experts back in 2002 or there abouts... please provide references.

Good for you Sander. I've been avoiding confronting the debunkers on that issue. And the more important one. "How many of them were loudly proclaiming 'Other than limit case B&Z Bazant is wrong' and here is why." 20/20 hindsight is a poor foundation for claiming "I wuz first". and who was first does not change the technical facts.

What I see is a crisis in critical thinking skills... and refusing to accept something because you don't like who said it.

That's the situation in a nutshell.

Put more bluntly that I did but...

...let's discuss the topic NOT character assassinate the person who posts some correct claims.

* Deliberate understatements.