Video Nullfies Pancake/CD Theory

reply to post by samkent


Hmm oh yes proven by the experts. Except the experts are not saying what you all claiming they are...

www.abovetopsecret.com...

The experts who wrote that paper quite clearly describe that catenary action does not pull in columns, but causes failure of the truss itself, assuming the connections don't fail first.

So when are you going to demonstrate sagging trusses pulling in columns? All this lip service but you can't demonstrate trusses pulling in columns.

Exponent thinks beams won't do it but trusses will. Esded only posts because he's jealous of peoples stars. None of you have shown anything by any expert that say sagging trusses can pull in columns.

Argumentum ad auctoritatem.

Originally posted by ANOK
reply to post by samkent

 

Hmm oh yes proven by the experts.

Except the experts are not saying what you all claiming they are...

www.abovetopsecret.com...

The experts who wrote that paper quite clearly describe that catenary action does not pull in columns, but causes failure of the truss itself, assuming the connections don't fail first.

Total lies ANOK. The paper you are discussing isn't even about trusses and it doesn't conclude that at all. I've already shown you this and quoted from a different paper by the same people that refutes your claim.

None of you have shown anything by any expert that say sagging trusses can pull in columns.

Not only have I:


You even quoted it here:
www.abovetopsecret.com...

You should also learn what the argument from authority fallacy is. You are literally using the same people to make authoritative claims, so either both sides are guilty or neither are. You can't decide that it's ok for you to use an unrelated paper but that others can't use specific papers on the exact subject.

Originally posted by Akareyon
The floor slabs don't have to hold any weight other than a few file cabinets and office desks. It's the core and the perimeter that is holding the floors up. What is it with you?

And don't have to either.

Then explain, what exactly is going to arrest the collapse in your building when a floor gets overloaded by something?

It is totally realistic because it successfully models the collapse. He's an expert at what he's doing, after all.

No it is not.

It can vary greatly with the distribution of the impact forces among the framed tube columns, between these columns and those in the core, and between the columns and the trusses supporting concrete floor slabs. For our purpose, we may assume that all the impact forces go into the columns and are distributed among them equally. Unlikely though such a distribution may be, it is nevertheless the most optimistic hypothesis to make because the resistance of the building to the impact is, for such a distribution, the highest.

So it says that uniform column to column impact is unlikely.

I don't have to because I know it by heart. He's talking about "loss of gravity", incosistently mixing in K and Wg and Wc and Wp until noone knows what's up or down anymore.

He never substracts Φ(u) from K for the K of the next story (K').

In his words:

As Wg was, for the WTC, greater than Wp by an order of magnitude, acceleration of collapse from one story to the next was ensured.

He just assumes that Wg was >> Wp. Obviously it was, otherwise, progress would have stopped. He never bothers to explain why he comes to the conclusion that Wg >> Wp other than that the towers collapsed. "The towers collapsed, therefor, collapse was inevitable."

Good he's the expert and I am not.

And here our discussion comes full circle again, just in other words: is Wg always greater than Wp in skyscrapers? Was it a feature unique to the Twins? If so, for what reason? Because it surely is not in card houses because Wc can only be smaller than Wb (Fig. 3) when it is already under tension (Fc < m*g) - and just waiting for an excuse to be triggered and snap together like a trap. Like your dishwasher tablet tower, for example.

You are starting to sound more and more like a denialist. I point you to the fact that in those papers the conditions when a collapse progresses and when it arrests are to be found, and you act as if ts just isn't there. At most you can disagree with those conditions, but claiming they are not there is denialism.

To get back to your interpretation, there is no reason at all to subtract Φ(u) from K as K is "kinetic energy of the impacting mass m(z)". K needs to be recalculated for each floor.

He didn't just assume that Wg >> Wp, he calculated that.

Calculating the dissipation per column line of the framed tube as the plastic bending moment Mpof one column ~Jira´sek and Bazˇant 2002! times the combined rotation angle (ui52p @Fig.2~b!# and multiplying this by the number of columns, one concludes that the plastically dissipated energy Wpis, optimistically, of the order of 0.5 GN m ~for lack of information, certain details such as the wall thickness of steel columns, were estimated by carrying out approximate design calculations for this building!.

He just didn't share his calculations. Why don't you redo them to show he is wrong? We have a lot more information available now. Why has nobody in the entire truth movement done this yet after 11 years?

reply to post by exponent


I think you are not reading that graph correctly mate.

Do you think the large displacement curve is the columns, or the truss?

But regardless that does not represent the WTC towers. You can't take a generic chart and claim that is what happened to the towers, because it is not based on the towers construction. The effects of fire and damage depends on the construction, and every building would be different. The WTC had massive core, and perimeter columns, and lightweight trusses, you do the math genius.

That chart is not taking into effect the WTC construction. You have the math in the PFD PLB supplied to figure out the force on the columns from the deflection. Why don't you use them?

But to do those calcs you would need to know how much stress the columns could withstand at the floor connections, and how much force the connection could withstand. Do you know those numbers? No, you don't because that information is not available. So you have nothing to support your claim.

So you still insist that bolts were stronger than the columns? Then you need to demonstrate that because nothing you have said, or shown, says that can happen. All you have shown is that trusses, and beams, can sag from heat, but we already know that. You are making a huge leap to go from trusses deflecting, to sagging trusses causing the columns to be pulled in, the huge leap that NIST made. That is why the NIST report is still an hypothesis, it can not be repeated in a lab. If it can, why have you not done that yet, and ended this discussion with real evidence?

Where is the evidence that sagging trusses can pull in the columns, and how did the connection not fail first?

Simple question that shouldn't need pages and pages of replies from you to answer. You are doing everything you can to avoid answering that question directly.

Originally posted by ANOK
reply to post by exponent

 

I think you are not reading that graph correctly mate.

Do you think the large displacement curve is the columns, or the truss?

It's both. It's a two axis graph. I am frankly at a loss to explain this question.

But regardless that does not represent the WTC towers. You can't take a generic chart and claim that is what happened to the towers, because it is not based on the towers construction. The effects of fire and damage depends on the construction, and every building would be different. The WTC had massive core, and perimeter columns, and lightweight trusses, you do the math genius.

It's not a 'generic chart'. As I have told you numerous times it is from "Effect of fire on composite long span truss floor systems". The extent of your ignorance is illustrated below:

That chart is not taking into effect the WTC construction.

From the paper which you clearly didn't bother to read:

In the aftermath of the events of 11th September 2001 it has
become more apparent that other structural forms need to be
investigated under fire conditions.

You might have even seen this figure, look familiar?


This figure is even available on the Science Direct page which shows you didn't even bother to read the abstract of the paper, nevermind the paper itself.

You have the math in the PFD PLB supplied to figure out the force on the columns from the deflection. Why don't you use them?

But to do those calcs you would need to know how much stress the columns could withstand at the floor connections, and how much force the connection could withstand. Do you know those numbers? No, you don't because that information is not available. So you have nothing to support your claim.

Au contraire, this information is actually available, for example here Newtons Bit calculates the deflection caused by a 6kips inward pull and obviously that is taken from the NIST report.

Whether you like it or not, this has been well studied and is well understood. Your continued refusal to even bother to read material supplied to you just illustrates that you're not really interested in what other people have to say.

Simple question that shouldn't need pages and pages of replies from you to answer. You are doing everything you can to avoid answering that question directly.

edit on 5/20/2013 by ANOK because: (no reason given)

I don't know how much more direct I can be than giving you the names of two papers that study it in depth, quoting from them, linking images from them and summarising them for you. Would you like me to drive to your house and physically bring you a copy next?

Originally posted by -PLB-Then explain, what exactly is going to arrest the collapse in your building when a floor gets overloaded by something?

The rest of the building. Newtons laws. Law of inertia. Bolts, weldsseams, tons of steel. Friction forces, the force to overcome the molecular bonds of the materials, bend and buckle columns, snap joints, break stuff. The same thing that arrests collapse in my Jenga tower, the tube full of eggs and lightbulbs, two cars crashing.

I point you to the fact that in those papers the conditions when a collapse progresses and when it arrests are to be found, and you act as if ts just isn't there.

I don't, I adapt to the new language you're proposing and argue within the new frame of reference.

He didn't just assume that Wg >> Wp, he calculated that.

You mean he reverse engineered Wp so the condition Wg >> Wp is met so the tower hits the basement just in time.

He just didn't share his calculations.

Guess why.

Because Wp = 0.5GJ*110=55 GJ, whereas the potential energy of the whole tower, Epot = m*g*h = 500,000,000 kg * 9.81m/s² * 400m / 2 ≈ 981 GJ = Wg and 981 GJ >> 55 GJ (insert for weight of the tower whatever you like). This is a metastable system; there is a huge energy (of which sort, I dare not speculate) hidden inside the building to help bring it down.

Are all skyscrapers metastable systems, waiting to be triggered by a small input energy like a mouse trap? If not, what was so uniquely different about the WTC, what is the one thing (or combination of things) to do when you're planning to construct a mechanical bomb?

Canned worms anyone?

Why does PLB keep on insisting the floors, or whatever, were overloaded?

What overloaded them? AFAIK there was no extra mass added to anything.

Again sagging trusses are not going to overload the columns, that is a complete fallacy that takes a little special twisting of what the professionals say in order to work.

Anyway here is the video of the collapse of the South Tower. Any sane person reading this thread can see from this video that the lower floors were blowing out ahead of the momentum of the upper section of floors. So the top had nothing to do with the collapse of the lower floors. Thus the collapse had nothing to do with sagging trusses, that were not sagging at all. If they did anything they buckled due to expansion, and being pinned between the core columns and the outer wall.



Angular momentum. If gravity was the only force acting on the collapse the top section could not have caused a symmetrical collapse, when acting under angular momentum. The weight of the top was not square on the floors, it was on the edge of the structure, the top was not rotating about a central axis. It should have continued it's angular momentum, and caused a lot of chaotic asymmetrical damage.



So not only is NIST's hypothesis for collapse initiation faulty, you guys explanation the collapse sequence is even more faulty. Don't you wonder why they didn't offer an explanation for the collapse sequence? Isn't the logical answer "they couldn't"? You want to assume collapse was inevitable once initiated, but that's just boloney, boloney I tell ya! Baloney because the collapse should never have been initiated in the first place.

Originally posted by ANOK
Why does PLB keep on insisting the floors, or whatever, were overloaded?

What overloaded them? AFAIK there was no extra mass added to anything.

Load was transferred from columns to floors.

Again sagging trusses are not going to overload the columns, that is a complete fallacy that takes a little special twisting of what the professionals say in order to work.

Well no it's what they explicitly say, to the extent that you're having to pretend posts don't exist to continue your ignorance.

Anyway here is the video of the collapse of the South Tower. Any sane person reading this thread can see from this video that the lower floors were blowing out ahead of the momentum of the upper section of floors. So the top had nothing to do with the collapse of the lower floors. Thus the collapse had nothing to do with sagging trusses, that were not sagging at all. If they did anything they buckled due to expansion, and being pinned between the core columns and the outer wall.

This is pretty much a textbook paragraph of someone desperately trying to change the topic but also who refuses to concede any point. You can't change the topic effectively if you're still insisting you're right ANOK. Especially when anyone who reads your posting can see you don't even bother to read sources. If you think that you can rely on a really badly compressed, low resolution youtube video to deny then you're just going to show yourself up worse.

Angular momentum. If gravity was the only force acting on the collapse the top section could not have caused a symmetrical collapse, when acting under angular momentum.

Well ignoring the fact that the collapse was hardly very symmetrical, the south tower as you said significantly tipped to one side, why exactly can the lower building structure not absorb this momentum? Can you even quantify it and show say a free body diagram?

The weight of the top was not square on the floors, it was on the edge of the structure, the top was not rotating about a central axis. It should have continued it's angular momentum, and caused a lot of chaotic asymmetrical damage.

The towers are not a homogenous tree. The 'edge' of the structure is the perimeter walls and the 'lowest resistance path' is actually to sever the floor connections internally and push the outer wall out in sheets. This is exactly what we see happen.

So not only is NIST's hypothesis for collapse initiation faulty, you guys explanation the collapse sequence is even more faulty.

I love the logic used here, one video to disprove NISTs hypothesis, one paragraph to deny the collapse sequence. Evidence or science? They're obviously for people who aren't right!

Don't you wonder why they didn't offer an explanation for the collapse sequence? Isn't the logical answer "they couldn't"? You want to assume collapse was inevitable once initiated, but that's just boloney, boloney I tell ya! Baloney because the collapse should never have been initiated in the first place.

Well that's convinced me, you've got a youtube video, refusal to read academic papers and now 'boloney' whatever that is. You really know how to put across a thorough point!

Just to taunt you a little with some relevant information, you know how you were saying that sagging trusses causing collapse takes some twisting of words? I wonder how I've twisted these:

The initial deflection rate matches closely. At about
250 s the deflection rate in the 2D analysis increases slightly.
This is the point in the 2D analysis when the column begins to
be pulled back inward by the deflecting floors. The deflection
rate then becomes more moderate at about 400 s as the rate of
heating in the steel reduces. Runaway failure is then obvious as
the building collapses.
Further analysis of results shows that this extra deflection is
caused by the failure of the column rather than further failure
of the truss. The column is pulled out of plane enough that
P–Delta moments cause plastic hinges to occur in the column
creating a mechanism. This then becomes a global phenomenon
and is outside the scope of this paper.

All I can do is laugh.

Originally posted by ANOK
Anyway here is the video of the collapse of the South Tower. Any sane person reading this thread can see from this video that the lower floors were blowing out ahead of the momentum of the upper section of floors. So the top had nothing to do with the collapse of the lower floors. Thus the collapse had nothing to do with sagging trusses, that were not sagging at all. If they did anything they buckled due to expansion, and being pinned between the core columns and the outer wall.

[vid]

Angular momentum. If gravity was the only force acting on the collapse the top section could not have caused a symmetrical collapse, when acting under angular momentum. The weight of the top was not square on the floors, it was on the edge of the structure, the top was not rotating about a central axis. It should have continued it's angular momentum, and caused a lot of chaotic asymmetrical damage.

Very much this, however, I was trying to remain within the frame of reference ;-)

That's a nice collection. What I find odd about the live footage of the south tower collapse is how people are crying, screaming and yelling "oh g*d, oh g*d, oh g*d" and "oh sh*t, sh*t, sh*t" at the top of their lungs all hysterically and live reporters' voices begin to tremble as they professionally describe the tower "exploding" before they realize it is actually totally collapsing as if they were surprised at what they're seeing

Did they not see the smoke? Where there is smoke, there is fire and of course the towers would come down when they were burning. What were they thinking? That the towers would withstand a fire and a plane crash? Surely noone can seriously have thought a structural failure would destroy a few floors at most before it stops -- it must have been obvious to everyone that once collapse is initiated, progressive collapse is inevitable. What were those people so shocked about then?

Is it because they were laymen who had to wait another two days before Professor Bazants finally explained there's nothing unusual about a skyscraper gracefully disappearing behind a huge cloud of its own dust and smoke?

No!

The destruction of the World Trade Center WTC on September 11, 2001 was [...] a big surprise for the structural engineering profession [...]. No experienced structural engineer [...] expected the WTC towers to collapse. No skyscraper has ever before collapsed due to fire. The fact that the WTC towers did, beckons deep examination.

- Mechanics of progressive collapse, Bazant/Verdure, 2007

But it's all oh so clear and obvious to defenders of the official conspiracy theory, and if you ask for that deep examination, it's because you're in denial of the obvious and lost touch with reality

Originally posted by Akareyon

- Mechanics of progressive collapse, Bazant/Verdure, 2007

But it's all oh so clear and obvious to defenders of the official conspiracy theory, and if you ask for that deep examination, it's because you're in denial of the obvious and lost touch with reality

edit on 21-5-2013 by Akareyon because: live

The extract you quoted precedes the deep examination you desire. It has been further extended and refined over the years in peer reviewed journals by a number of different authors including the papers I quoted above.

Originally posted by exponent
The extract you quoted precedes the deep examination you desire. It has been further extended and refined over the years in peer reviewed journals by a number of different authors including the papers I quoted above.

Originally posted by samkent
It's amazing how the same few people can argue for so long on an issue the experts have setteled long ago.

However, good to hear that they're still working at it, exponent. I bet the examination went all 3D and FEM stuff in the meantime and waay above my head. Is there any agreement yet on whether all towers are built like that and in the case they're not, which structural particularity caused the implosive explosion mechanism of the Twins? I would love to hear some good news!

Originally posted by Akareyon
However, good to hear that they're still working at it, exponent. I bet the examination went all 3D and FEM stuff in the meantime and waay above my head. Is there any agreement yet on whether all towers are built like that and in the case they're not, which structural particularity caused the implosive explosion mechanism of the Twins? I would love to hear some good news!

I'm not sure what you mean by 'all towers are built like that' but the reason for the towers violent demise has been known since the final NIST report in 2005. I'm sure I mentioned this to you earlier that having working sprinklers was key above all else, but that the ultimate failure mechanism was the failure of columns due to fire induced floor damage. The collapsing structure then stripped floors from the columns as it descended. This is not something the buildings could possibly resist.

Originally posted by exponent
[...]the ultimate failure mechanism was the failure of columns due to fire induced floor damage. The collapsing structure then stripped floors from the columns as it descended. This is not something the buildings could possibly resist.

I'm fine with any explanation for the initiation of the collapse, I'll go along with Bazant and pretend one floor was removed and there was a one story freefall.

So, the collapsing stucture then stripped the columns as it descended, which in turn caused the columns to buckle under their own weight, right? Sounds like the engineers made some big, big, big mistake, doesn't it? Maybe not and all skyscrapers have this flaw built in, I'm no expert, I just wonder.

Because if it was an engineering failure unique to the Twins, I would find it strange that none of the white-collar victim's families sued the hell out of those engineers for compensation of their loss in a legal system where you can sue McDonald's for serving hot coffee.

Originally posted by Akareyon
The rest of the building. Newtons laws. Law of inertia. Bolts, weldsseams, tons of steel. Friction forces, the force to overcome the molecular bonds of the materials, bend and buckle columns, snap joints, break stuff. The same thing that arrests collapse in my Jenga tower, the tube full of eggs and lightbulbs, two cars crashing.

The rest of the building is no longer attached to the floors once they fail. How is the load going to be transfered to the columns in your design?

Guess why.

Because he points to a reference so that everyone knows how he calculated it and can reproduce it?

Because Wp = 0.5GJ*110=55 GJ, whereas the potential energy of the whole tower, Epot = m*g*h = 500,000,000 kg * 9.81m/s² * 400m / 2 ≈ 981 GJ = Wg and 981 GJ >> 55 GJ (insert for weight of the tower whatever you like). This is a metastable system; there is a huge energy (of which sort, I dare not speculate) hidden inside the building to help bring it down.

(Almost) every building is a metastable system. Why do you think that controlled demolition works? The stable state of any building would be for every individual member to be at ground level.

You don't need to speculate about this energy, you already state what it is: potential energy. It is not hidden, it is out in the open.

Are all skyscrapers metastable systems, waiting to be triggered by a small input energy like a mouse trap?

Yes, that is why controlled demolition works. For instance, take a look at this one:

www.bbc.co.uk...

Only 88kg of explosives. Peanuts compared to the potential energy in that building.

If not, what was so uniquely different about the WTC, what is the one thing (or combination of things) to do when you're planning to construct a mechanical bomb?

Canned worms anyone?

It probably had some unique features, but the ability to collapse with a relatively small energy input is not one of them.

Originally posted by ANOK
Why does PLB keep on insisting the floors, or whatever, were overloaded?

What overloaded them? AFAIK there was no extra mass added to anything.

Maybe you missed this, but a top section fell on them. You can see it happening in youtube videos if you are wondering.

reply to post by ANOK

What overloaded them? AFAIK there was no extra mass added to anything.

This is just a guess on my part but does an airplane count?

Originally posted by bottleslingguy
It seems to me that if the core was still standing AFTER the collapse the whole cd theory flies out the window.

Not at all. It doesn't matter whether it was the core or some other vertical structure in the building that didn't follow the "pancakes" to the ground (the video is not 100% clear on this, but it doesn't matter). Thing is, the key in the pancake theory is exactly that the "pancakes" (floors etc) get decoupled from the structures that are supposed to keep them in place. You can make a model with 4 vertical rods and square pieces as representation of the floors, glued to the rods in the corners. Then you can make it pancake without the rods being destroyed.

Originally posted by -PLB-

Originally posted by ANOK
Why does PLB keep on insisting the floors, or whatever, were overloaded?

What overloaded them? AFAIK there was no extra mass added to anything.

Maybe you missed this, but a top section fell on them. You can see it happening in youtube videos if you are wondering.

Indeed, and it always was a crucial part of the pancake theory.

Originally posted by -PLB-
The rest of the building is no longer attached to the floors once they fail. How is the load going to be transfered to the columns in your design?

When it is not transferred, the columns cannot fail because the whole mass - if you somehow manage to move it over the floor slabs - just crashes into the basement without its force acting on the columns in any way. Perimeter and core remain standing, because they are stable on their own by design and definition.

(Almost) every building is a metastable system. [...] The stable state of any building would be for every individual member to be at ground level.

But then it would not have the same potential energy, would it?

You don't need to speculate about this energy, you already state what it is: potential energy. It is not hidden, it is out in the open.

Sure it is. But that energy is like ten gallons of diesel packed in a plastic bag instead of a steel tank - not very well contained, obviously.

Are all skyscrapers metastable systems, waiting to be triggered by a small input energy like a mouse trap?

Yes, that is why controlled demolition works. For instance, take a look at this one:

www.bbc.co.uk...

Only 88kg of explosives. Peanuts compared to the potential energy in that building.

88kg of explosives, intelligently placed. Just throwing them through an open window would hardly have the same effect. Intelligence, planning and intention are a form of energy, as it seems. You're getting very close to what I'm trying to say here...

Just like a bunch of domino randomly set up on a given area will not completely collapse progressively, only if you set them up intelligently so they do.

Originally posted by Akareyon
When it is not transferred, the columns cannot fail because the whole mass - if you somehow manage to move it over the floor slabs - just crashes into the basement without its force acting on the columns in any way. Perimeter and core remain standing, because they are stable on their own by design and definition.

But that was exactly what I was saying earlier on. So you still have progressive floor collapse, but in your design the columns are still standing afterwards.

Let me put it another way. What exactly is the benefit that after collapse your columns are still standing, compared to a situation where the columns collapsed along with the floors?

But then it would not have the same potential energy, would it?

Nope. What is your point exactly?

Sure it is. But that energy is like ten gallons of diesel packed in a plastic bag instead of a steel tank - not very well contained, obviously.

I haven't noticed skyscrapers collapsing all over the world, so its pretty well contained.

88kg of explosives, intelligently placed. Just throwing them through an open window would hardly have the same effect. Intelligence, planning and intention are a form of energy, as it seems. You're getting very close to what I'm trying to say here...

Just like a bunch of domino randomly set up on a given area will not completely collapse progressively, only if you set them up intelligently so they do.

Either intelligent placing, or just overkill. Either is possible. A plane impact with subsequent fires obviously was a massive energy release compared to explosives. At least it was enough to make 1 or 2 floors of that building fail. The energy that was released when the top started falling completely dwarfed any kind of explosives, as you already figured out with your potential energy calculations.