Kuttler's paper: Estimates for time to collapse of WTC1

[Hitstirrer]

At the risk of adding a prologue to the epic, you may want to start with this. This is the train analogy with my mistake added in.

I will get around to your full explanation, but your prologue popped up first.

Analogies rarely capture all the nuances that they are intended to display and usually disappoint both the presenter and the reciever. I fear thats the case with yours - and will be by mine as below.

One analogy that was suggested many years ago still holds some merit though. The classic one about a line of cars.

To set the scene. The towers were far stronger at the base than the top - somewhat like a pyramid but without that shape. They were built in thirds with the lower third using much thicker steel sections than above.Then the central third less heavy steel and the top third relatively thinner steel. In addition there were some floors that were very heavily constructed as they were designed to hold heavy machinery and plant rather than office furniture.

The analogy proposes a line of cars with 35 Hummers nose to tail followed by a USP truck ( engineeer floor ) then 35 SUVs followed by a USP truck, then 35 saloons followed by a golf cart. All nose to nose with no gaps and the first Hummer parked against a cliff. Every vehicle to comply with current regulations on crumple zones front and rear.

Then half of the saloons and the cart are close coupled together and backed off to create a space. Into that space is inserted the badly burned shell of a saloon that has been sideswiped by a truck and is bent out of shape and very weak structurally. Then, you arrange for the ones you backed away to all engage drive together and accerate forwards as a solid mass at 32ft/s/s to finally destroy the burned out saloon and together strike the undamaged crumple zones of the next saloon.

(NB. For the purists this contavenes Bazants paper because he assumed that the burned out car didnt exist and just left that space vacant to allow the accelerating cars to achieve 19mph before impacting the first saloon. Just another problem to ponder on here )

Would that upper block of saloons crush very far into the line of parked cars ?

Of course an initial complaint would be that the first car, and subsequent cars to be struck, would have to fire their engines up instantly at impact, and drive themselves forward at 32ft/s/s to simulate gravity. To allow the analogy to proceed it must now be imagined that this line of cars is somehow being held vertically so that no engine power is needed and just gravity is to be the total motive power. The first Hummer in line now nose on the ground.

Would the upper block of saloons crush very far into the line of (now vertical) cars ? Or is it more likely that the fall would be arrested, or that the upper block was forced off to fall to one side.

Through the crumple zones of the remaining saloons, designed to absorb energy, ( like deforming steel ) - pulverise anything that isn't steel and throw that debris over a radius of many miles - then destroy a USP truck - then 35 SUVs and so on until all of the Hummers also destroy themselves and eject all their pulverised fittings to the four winds too. And to do all that in a perfectly vertical direction. At no time does the accumulating line of crushing cars get diverted to one side and fall away. They remain firmly in line and proceed in that line from start to finish.

Hmmmm. That is what we are asked to accept though.

Alternatively, just line up a School bus, a Hummer and saloon and drive a VW Golf GTI into the back at 100mph. Does it crush through the lot or is it thrown to one side due to any slight non symmetrical force ?

Either way - even though I hate analogies - they do sometimes highlight the problem as observed by many people.

Back to your epic entry though @OneWhiteEye. I will let you have my comments on that in due course.

 

[qed]

Hmmmm. That is what we are asked to accept though.

No.

• That is not what you are asked to accept.

I used to think of the building like that, but the building looks much more like this.

┃--------------------┃--┃--┃--┃--┃--┃----------------------┃
┃--------------------┃--┃--┃--┃--┃--┃----------------------┃
┃--------------------┃--┃--┃--┃--┃--┃----------------------┃
┃--------------------┃--┃--┃--┃--┃--┃----------------------┃
┃--------------------┃--┃--┃--┃--┃--┃----------------------┃
┃--------------------┃--┃--┃--┃--┃--┃----------------------┃
┃--------------------┃--┃--┃--┃--┃--┃----------------------┃

The solid vertical lines are the columns.
The dashed horizontal line are the floors, concrete on steel struts.
There is absolutely no other vertical support.

• Realizing this led me understand how WTC was likely to collapse. When I used to think of the building your way, I could no fathom how the buildings collapsed.

So it is all about breaking each floor.

For example, if a object with enough enough mass to break one floor is placed on a floor, it will break through, fall to the next, break through, and on all the way to the bottom.

      ▇
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃

The building was a stack of bridges.

 

[Mick West]

[quote="qed, post: 79237, member: 2370"

      ▇
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃
┃----- --------------┃--┃--┃--┃--┃--┃----------------------┃

The building was a stack of bridges.[/quote]

Minor expansion on your diagram:


Back to Kuttler one might consider an abstract best case where a SOLID top block is falling between two columns, pushing them away and out and stripping the floors off them:



Now of course this does not reflect the setup, however it does reflect the actual collapse mechanism a lot better that Kuttler's hovering blocks. In reality there are a lot more columns, and it's 3D. However, the stripping of floors and the sideways pushing of unsupported columns is what appears to have happened in the WTC collapse. It was done mostly by a compact wave of rubble and not by a solid block, but the principle is the same.

 

[Hitstirrer]

When I used to think of the building your way ..........

So it is all about breaking each floor.

The building was a stack of bridges.

I have always known how the buildings were constructed. I have always been astonished at the way that massively strong core system fell through itself. The stack of two dimentional bridges in your drawing doesn't really show that they were in fact three dimensional. There were dozens of such bridges ( trusses ) spaced evenly all around the inner core system. Sure -- a single truss can sag and allow concrete to fall. Quite a few trusses could sag. If so, than quite a fair section of floor would fall. But the entire three dimensional floor area fell all at once.

There was a truss spanning from every outer column to the core all around the building. Dozens of them. All of them would have had to break away from their individual column connections simultaneously to allow the entire concrete floor at any one level to fall at the same instant. How can that happen ?
But of course what you are really describing is the long discredited 'pancake' theory. You imagine floors piling onto floors onto floors and ignore the immensly strong core system not involved in any floor to floor action. How did the core columns - all braced to each other to form an intense steel grid with huge redundancy built in - also manage to fall through the line of most resistance ?

But this is going off topic.

And as @OneWhiteEye says, I am not sure that Kuttler has any real clue about engineering in order to fully model the building so that realistic parameters can be set for calculations. He simplified input as if the building was simple. It wasn't. But, and its a big but, even treating it as a simple stack of hovering concrete floors he found it hard to justify fall times observed when other energy requirements are factored in.

If Kuttler fully understood the interdependancy of the core/bridging truss system/outer columns and was able to model and calculate accordingly, surely it would result in a slower fall time than a simple floor to floor drop with zero resistance between floors and no resistance from that core. And even the simple models couldn't be made to comply with the vids seen. Something else, producing some other energy source, would be required to square the circle.

 

[Mick West]

If Kuttler fully understood the interdependancy of the core/bridging truss system/outer columns and was able to model and calculate accordingly, surely it would result in a slower fall time than a simple floor to floor drop with zero resistance between floors and no resistance from that core. And even the simple models couldn't be made to comply with the vids seen. Something else, producing some other energy source, would be required to square the circle.

But once the core columns are no longer aligned, they offer essentially no resistance. The floors get stripped off them, they get pushed by the wave of rubble, they fall. In painfully inaccurate analogy, the upper block is acting like the slider in a rather complicated zipper.

The zipper is very strong in one way, but very weak in another. Kuttler models neither.

 

[Mick West]

How did the core columns - all braced to each other to form an intense steel grid with huge redundancy built in - also manage to fall through the line of most resistance ?

They didn't. The individual falling columns would quickly become offset from the matching column underneath. The columns would only have to hit the floors and core bracing.

When people talk about the immensely strong core column, they usually show the photo of the core at the base of the building. But in the initial collapse zone the columns were a lot thinner, and there was less bracing. This is the image they should be looking at:

 

[Hitstirrer]

Minor expansion on your diagram:

Nice drawings ! They show me clearly how you imagine collapse began. You show an entire floor, including the core, falling at the same instant.

But we saw the antenna fall first. Meaning that the core must have dropped first.

Now I can sort of understand sagging trusses weakened by heat. And I can accept that they could be a seat of failure. But I find it hard to reconcile the core system, where there was hardly any flammable material, being the first to drop suddenly. Of course I'm aware that some core columns were badly damaged - cut perhaps - all on the same side as the outer column damage. Wouldn't that mean that undamaged core columns and/or undamaged outer columns on the other side, would act as a fulcrum/hinge to allow the top, as a block, to sag into the damaged area. Rather than the undamaged columns offering identical zero resistance as the badly damaged ones, so that the entire core drops symetrically. Puzzles me that.

But your drawing shows that you have accepted that conundrum as normal.

Fortunately, Kuttler wasn't troubled by such niceties either. He just tried to model it simply as a whole floor without any troubling extra resistance which would force the fall times to be way out of line.

 

[Mick West]

I think you read a little too much into my diagram It's to illustrate the general principles. Reality is much more complicated.

I'm not sure where you are getting this "antenna drops first". In Sauret there is some downward movement of some exterior columns at the same time as the first detectable downward motion of the antenna, and gross movement of the entire upper block within 0.33 seconds. But perhaps you'd like to start a thread debunking something in particular regarding that?

 

[Hitstirrer]

But perhaps you'd like to start a thread debunking something in particular regarding that?

No thanks. But it would be good to understand how the core managed to move down first. ( even if only 1/3rd sec before any other move was detected )

On reflection its a bit worse. Because the antenna was sat centrally on the hat-truss. And the hat-truss outer perimeter, attached to all of the outer columns, didnt move when the antenna dropped. Now that is a mystery. But, as you say, another thread for someone to play with.

 

[OneWhiteEye]

Analogies rarely capture all the nuances that they are intended to display and usually disappoint both the presenter and the reciever.

Is that your experience? I can't say the same.

I fear thats the case with yours - and will be by mine as below.

Your analogy is fine. We just need to figure what's different between your analogy and the actual buildings and maybe something will be learned. My analogy is meant to illustrate what Kuttler was doing versus what he should've been doing rather than some analogy for the collapse itself. Different purposes. Hopefully you aren't disappointed once you check it out but I'll brace for it any case.

I'm perfectly fine with the slab model Kuttler uses. There's nothing wrong with that aspect. A few tweaks and it would give good results.

I'm not going to add any more epic material to read at this time.

 

[OneWhiteEye]

I am going to ask one question, though. In this area, whose work would you accept? You obviously don't care for Bazant. Do you think Tony Szamboti's work is worthwhile, or is it bunk of the same sort as Bazant's? I ask because at some point I'd like to compare Kuttler's methodology to others to illustrate the differences. If I pull out references for explanatory purposes, it will help if the points those references make are already accepted by someone whose analysis you trust so that the petty points don't need to be hashed out in excruciating detail.

Some of what you said in your posts in the last page looks similar to stuff I was saying years ago when first looking at this. I don't think the gap between our views is as great as it appears on the surface.

 

[Hitstirrer]

I believe qed understands it, and I know Mick does.

I hope I've satisfactorily explained both my error and his.

First of all I would like to thank you for your response.

I believe that Mick may follow you.

For myself I am still very unclear except to note that obviously omitting the action of total elements would seriously affect the outcome. I can imagine using his concrete floating slabs model but adding the mass of steel to the load to simulate correct dynamics. That full load under gravity would obviously force a larger interaction than if the mass of steel was not there - even if the steel takes no part other than add mass. Does that make any sense ?

 

[qed]

No thanks. But it would be good to understand how the core managed to move down first. ( even if only 1/3rd sec before any other move was detected )

On reflection its a bit worse. Because the antenna was sat centrally on the hat-truss. And the hat-truss outer perimeter, attached to all of the outer columns, didnt move when the antenna dropped. Now that is a mystery. But, as you say, another thread for someone to play with.

Is this true? Can someone explain this?

Perhaps a topic for another thread?

 

[OneWhiteEye]

First of all I would like to thank you for your response.

You're welcome. I'm sorry for being a condescending prick. It comes too easily.

I believe that Mick may follow you.

For myself I am still very unclear except to note that obviously omitting the action of total elements would seriously affect the outcome.

Yes! That's the essence of it. Omitting elements could go either way in terms of affecting collapse time, depending on what those elements are. In this case, omitting 80-90% of the mass while still requiring that all the concrete be crushed creates a physically impossible situation. If the rest of the mass isn't there, then the majority of concrete simply wouldn't be crushed to 100 microns. The additional mass involves proportionally more potential energy (mgh) which is the sole energy source to drive this whole process. Take most of that away, and it isn't reasonable to expect that the same damage to the concrete would be done.

In other words, the concrete alone is not capable of crushing itself to the same degree as the combined mass would. If it is forced to be crushed by deducting the energy via 'decree' rather than by observing conservation laws, the collapse time will be artificially inflated. Greatly.

I can imagine using his concrete floating slabs model but adding the mass of steel to the load to simulate correct dynamics. That full load under gravity would obviously force a larger interaction than if the mass of steel was not there - even if the steel takes no part other than add mass. Does that make any sense ?

Yes. I think you understand this. Of course, adding structural steel adds structural resistance, but there was a lot more mass than structural steel omitted. We can tackle the resistance added by including the columns once the simpler slab model is fixed up.

 

[OneWhiteEye]

Is this true? Can someone explain this?

Perhaps a topic for another thread?

It's probably worthy of its own thread. I'm mostly agnostic about core-first failure, but there actually is some evidence for it (depending on your interpretation of fine measurements).

 

[OneWhiteEye]

I'm sorry for being a condescending prick. It comes too easily.

However, if I can bring you along from where you are to where I am, then give you a few years trying to explain these things to people who haven't grasped them yet, we'll see how long you can hold out before you break down and act like a prick, too. Hopefully, not as quickly as me. Again, sorry for taking untold baggage into a fresh discussion with you.

 

[qed]

It's probably worthy of its own thread. I'm mostly agnostic about core-first failure, but there actually is some evidence for it (depending on your interpretation of fine measurements).

I have looked at the referenced video, and noting

I'm not sure where you are getting this "antenna drops first". In Sauret there is some downward movement of some exterior columns at the same time as the first detectable downward motion of the antenna, and gross movement of the entire upper block within 0.33 seconds.

my curiosity is sated. So I will not be opening that thread.

 

[Hitstirrer]

I am going to ask one question, though. In this area, whose work would you accept? You obviously don't care for Bazant. Do you think Tony Szamboti's work is worthwhile

As I have said, I do not have the expertise to duplicate others calculations to check accuracy. But the more involved I becomes the clearer it is that its not the maths thats the problem at all. That is always a constant that cannot be open to interpretation. Its entirely dependant upon assumptions and parameters that are made in order to programme algorithms and formulae. I first became aware of that when poring over NISTs reports. In particular their final report on WTC7. This isn't the thread to go into that further but suffice to say that some of the programming parameters that they used to produce the computer simulations were, in my opinion, fraudulent and produced false results of course. ( GIGO )

I am also aware that 'peer review' means very little - having made a few discreet enquiries myself into a totally different area of expertise. The closed circle of 'peers' who review each others work is scary in some disciplines. Its also further under question when you consider that many people reading the 'peer reviewed' papers in learned journals will decline to offer any criticism - even if they do find some aspects troubling - because they do not want to rock the boat inside their own chosen field. More so because they are in a narrow field of research and quite like to keep their jobs and not be known as a troublemaker.

All this makes it hard for me to 'pick sides' as you ask.

As to TS. I have worked with him on different projects for some time. I have always found him to be a straight talking, honest and knowledgable engineer. He has no difficulty in admitting mistakes, and is quite willing to amend his position slightly, over even tiny points, simply for absolute accuracy. It indicates to me that he is constantly 'worrying' over details to avoid being accused of errors by others. I like that about him. At present I am working with him in a small team of mixed expertise specialists on a project, and we will be releasing details fairly soon.

But, of course, that does not mean that I take his every word as gospel. Any more than I take yours, Kuttlers or Bazants. To be absolutely frank with you I find that navel scratching over isoteric and philosophical simulations in a computer model, or programme, does not replace real experimentation- despite Shyam Sunder insisting that his protocols are robust.

This means that I cannot give you the name of my preferred 'expert', because basically I have no means of making that decision. The way I play it is to wait for input from someone. Then check it against others work. If there is a large difference in conclusion I look for reasons. Sometimes its as simple as different input data as mentioned above. I sometimes pester people like you. But my aim is always driven by a search for truth - whatever people in here think of me thats a fact.

If you still think that its worth writing 'epics' to try to get my brain in gear thats fine. If not, then thats fine too.

 

[OneWhiteEye]

But my aim is always driven by a search for truth - whatever people in here think of me thats a fact.

I believe that.

 

[OneWhiteEye]

Would that upper block of saloons crush very far into the line of parked cars ?

No.

Would the upper block of saloons crush very far into the line of (now vertical) cars ?

No.

Or is it more likely that the fall would be arrested, or that the upper block was forced off to fall to one side.

Yes.

Obviously I need to explain some differences between a stack of cars and a skyscraper! This is a common analogy actually.

Through the crumple zones of the remaining saloons, designed to absorb energy, ( like deforming steel )...

There's a clue here: "crumple zones... designed to absorb energy..." Is anything in the towers designed to be a crumple zone, to absorb energy in dynamic crushing? No. A skyscraper is designed for static load, wind loading and perhaps seismic loading. It is not designed to have one part of it crash into the other. This is THE key point and I will explain the differences in terms of resisting force and total energy dissipated later when I get back. This will include supporting references for both structural columns and crumple zones for comparison.

The brief summary is: Crumple zones (and automobiles in general) are much stronger than skyscrapers, relatively speaking. MUCH, MUCH stronger than skyscrapers. That might seem counterintuitive, but it is provably so. I read somewhere once that an empty aluminum can could support the weight of over 7000 cans like it. Even assuming a factor of safety of 5, how many towers could you stack on top of one tower?

The perception of the towers as immutable monoliths is largely illusion.

 

[OneWhiteEye]

I read somewhere once that an empty aluminum can could support the weight of over 7000 cans like it.

I also saw a video from Mick somewhere that shows what happens when standing on a can and perturbing the side slightly. Very instructive.

 

[OneWhiteEye]

Oh, and one other quick comment (frankly I always hope the quick comments will suffice rather than tomes)...

Are you familiar with verinage? If you're a collapse junkie, undoubtedly you are. They're not always successful, some arrest. But most are successful. There are numerous documented instances of one-half to as little as one-fifth of a building totally crushing the larger bottom portion and itself to rubble. Concrete crushed, large dust clouds (compare 15 stories and 1/4 the footprint to the 110 story towers). Smaller like meets bigger like and both are pulverized.

Does that happen with a stack of cars? No, we already agree it doesn't. But it DOES happen with buildings, proven by experiment. Is there any particular reason it wouldn't be expected to happen with much taller buildings? Bear in mind, the factor of safety is not greater just because the building is taller. A minimum FOS of (e.g.) of 2.5 is a typical design standard. If anything, a very tall building has to shave it as close as safely possible, where the absolute capacity of a 3-5 story building may be the same for all stories and the bottom story which sees all the load is FOS 2 and the rest of the stories greater.

 

[qed]

AI am also aware that 'peer review' means very little - having made a few discreet enquiries myself into a totally different area of expertise. The closed circle of 'peers' who review each others work is scary in some disciplines. Its also further under question when you consider that many people reading the 'peer reviewed' papers in learned journals will decline to offer any criticism - even if they do find some aspects troubling - because they do not want to rock the boat inside their own chosen field. More so because they are in a narrow field of research and quite like to keep their jobs and not be known as a troublemaker.

This is absolutely not true regarding rated/respected journals.

Academics tear their peers to shreds if they find an error in a published paper. They are in competition.

It is embarrassing to the journal. The peer reviewer who missed the error will be avoided by that journal again.

 

[Hitstirrer]

.

 

[Hitstirrer]

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[Hitstirrer]

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[Hitstirrer]

Something odd going on when I post. I will try this way instead.

@OneWhiteEye - You said " Are you familiar with verinage?".

That is frequently brought up. Find me a highrise steelframe building where vérinage alone has been used to cause global collapse and we can discuss that further. Until then its a pure diversion and quite frankly it surprises me that you suggest it. To excuse you a little, vérinage does very clearly show the interaction when one concrete mass impacts under gravity on another concrete mass, to produce much pulverised dust. But is that a surprise ?

But vérinage also relies on massive individual 'jolts' to achieve its objective doesnt it ? ( There is that 'jolt' word again.) Vérinage doesnt show constant acceleration as seen in the towers. But its no doubt covered in a different thread, so I prefer to leave it to be debated there.

 

[Hitstirrer]

Academics tear their peers to shreds if they find an error in a published paper. .

I held that view too. My research showed a different picture.

 

[Hitstirrer]

Obviously I need to explain some differences between a stack of cars and a skyscraper! This is a common analogy actually.

There's a clue here: "crumple zones... designed to absorb energy..." Is anything in the towers designed to be a crumple zone, to absorb energy in dynamic crushing?

You don't need to explain the difference between cars and towers. And yes its a common analogy. I said that. I also said that analogies rarely satisfy either the presenter or the receiver. Of course buildings arn't designed with crumple zones. 50 years ago cars wern't either. But if one 1960 car collided in the rear of another stationary 1960 car at speed they both crumpled. Just with a very large rate of deceleration. The aim of a car's crumple zone is to absorb that impact at such a much slower rate so that human organs are not suddenly 'jolted' and rupture. Such a large 'jolt' in a 1960 car crash killed people. A building encountering a sudden impact from above - but absent a crumple zone - would 'jolt' like that too. Absorbing energy rapidly. Now where have I seen a debate about a 'jolt' before ?

 

[Jazzy]

Is this true? Can someone explain this?

Immediately after the plane impacts there were thermobaric explosions which reached both roofs and basements via the elevator shafts. These cleared spaces formed chimneys.

WTC1 stood for longer, its impact was higher up, and its interior columns and top hat truss were subject to more heat for a longer period of time.

.

 

[Hitstirrer]

Immediately after the plane impacts there were thermobaric explosions which reached both roofs and basement via the elevator shafts. These cleared spaces formed chimneys.

WTC1 stood for longer, its impact was higher up, and its top hat truss was subject to greater heating for a greater period of time.

.

You should be writing fiction books with such an imagination.

 

[Hitstirrer]

@OneWhiteEye - You said " Are you familiar with verinage?".

There is another amusing aspect when véronage is mentioned. Its a form of CD.

 

[qed]

I held that view too. My research showed a different picture.

Please give us an example of problems in the peer review process of rated academic journals. I know of one famous example in a Soc Sci journal, but a science journal?

 

[qed]

@OneWhiteEye - You said " Are you familiar with verinage?".

There is another amusing aspect when véronage is mentioned. Its a form of CD.

You do not seem to be able to follow a logical line of reasoning.
What is the point of this remark given the context.

 

[Mick West]

This presentation (attached) has a discussion of Verinage issues. But it also has some good illustrations of the "Zipper" analogy I brought up earlier, described here as a Wedge:

Again though, this is a simplification. Two dimensional. However it illustrates the direction in which we need to go if we are to arrive at an accurate and realistic model.

 

[Jazzy]

You should be writing fiction books with such an imagination.

Thank you. I have always used my imagination to create things. If it ever fails me I should probably follow your example of giving bad advice to people who didn't need it.

Something odd going on when I post.

Why not delete your posting failures?

 

[Hitstirrer]

But regarding "what actually happened", would you agree that a reasonable model to try would be:

• The upper block of floors started to fall
• The core columns were quickly misaligned
• The falling mass stripped away the floors from the core columns
• The outer walls/columns fell outwards
• The inner columns would lose lateral support as the floors were stripped away
• The inner columns would be pushed laterally by falling columns, in addition to being impacted from above
• The majority of the energy expended by the falling mass would be used in stripping the floors from the columns
• The inner columns would fail mostly at the splices, not bending, from lateral forces

So that might be a better model to figure out the numbers for?

OK. Breathing space to return to your earlier question.

Reasonable sequences for Kuttler to work on.

" What actually happened" is what the debate is about isn't it ? Your list is your particular version. Your first point is actually what NIST said. But they covered all of your other points by simply saying - " global collapse ensued".

That neatly avoids having to answer the key question. What allowed the upper block to fall so symetrically, when most of the columns supporting it were undamaged ?

NIST's answer to that is that fire caused every truss on one floor to sag centrally by 43". The geometry of that sagging of every truss meant that every outer column was pulled inwards sufficiently to create a kind of vérinage effect at the entire outer skin of the building. Simultaneously.

(Incidentally, Kevin Ryan says that they only sagged 4" in tests, where a double load was imposed, double temperature and for double the time. And the truss ends not restrained at either end, allowing a maximum sagging possible. 4" was the result. He was concerned at seeing the report prepared to go to NIST saying the sag was 43", and was fired when he went directly to NIST to tell them that. )

To be fair, the inward move of the outer wall is what we saw. And if every truss sagged by 43",( koff) simultaneously, and rapidly, then that would be the result. But to backtrack a bit. We earlier discussed the very first indication of movement. People play down the antenna move as only being 0.33 second before significant upper block movement. If the antenna, sat on the core, did indeed drop first ( for some unknown reason ) as indicated by that 0.33 second - how far would it fall in that time ? Sufficient to pull down every truss attached to the core ? Enough to then pull the outer wall columns inwards ? As observed?

Something caused the outer walls to " vérinage ". If Kevin Ryan is correct then the truss sag theory is suspect. Sagging requires symmetry thats hard to imagine in organic fires. But the 0.33 seconds drop is accurate. Core dropping as a unit automatically induces symmetry.So which theory about initiation hold most water at this stage ? We saw the 0.33 seconds. We must call KR a liar to accept the sag.

To get back on track. You ask for realistic sequencies to suggest to Kuttler to model.

I wouldnt argue with your suggestions much apart from initiation of course. and with the exeption of this one.

" The majority of the energy expended by the falling mass would be used in stripping the floors from the columns"

I would change that to read " Some of the energy .....etc ".

After all, that is where most of such modelling errors are made. I suspect that a lot of energy was required to pulverise and eject material - and also heat it to very high temperatures as reported by ones engulfed in it. Then there are huge and rapid ejections of large steel sections to be catered for. Your 'majority' word doesnt seem right to me.

 

[Hitstirrer]

Why not delete your posting failures?

Sorry. I didn't know you could do that. Havn't learned how to drive this site fully yet. Best I could do was delete the text but it insisted on there being some text left. Hence the full stop.

 

[Hitstirrer]

You do not seem to be able to follow a logical line of reasoning.
What is the point of this remark given the context.

[...] People use vérinage to prove that buildings can come down using its own mass as motive force. Agreed. It can do that. Apart from the fact thats its irelevent in connection with steelframe buildings. But whats amusing is that vérinage is a form of CD. That means that they offer a CD initiation to prove that it wasn't CD. Geddit ?

 

[Hitstirrer]

Please give us an example of problems in the peer review process of rated academic journals. I know of one famous example in a Soc Sci journal, but a science journal?

I prefer not to.