Moderated Steel structures cannot globally collapse due to gravity alone

[KreeL]

Heiwa's analysis of Bazant's paper is quite correct.

State of grace - the floor trusses weren't the main parts of the towers absorbing the brunt of the falling block. The lattice-work of thousands of steel beams, and the 47 core columns were tremendously more than enough to arrest a 20-30mph impact by the top 15%. Resistance would have been so overwhelming that the top block would have stopped immediately.

 

[e^n]

If it was applied under the fireproofing, why is it that it is not visible in the various inspection photographs that are available?

For that matter, how was it even applied without having to close down entire sections of offices, seal them off, remove the existing fireproofing, add the thermite and then re-apply fireproofing?

As usual, this is an idea that might sound plausible to someone without a good understanding of the subject. Mackey is someone you should listen to.

edit: must have had this thread open from earlier! Apologies for the late reply

 

[Christopher7]

Bazant's theory requires that all the accumulated weight be applied evenly.

That is NOT what happened!

The top section of the south tower is not applying its weight evenly.

 

[Gravy]

Bazant's theory requires that all the accumulated weight be applied evenly.

That is NOT what happened!

Exactly! Bazant made a conservative assumption that is grossly in favor of collapse arrest. Yet the calculations show that the structure fails even when a perfect axial load is evenly distributed. Truthers choose not to grasp this simple concept.

 

[stateofgrace]

Heiwa's analysis of Bazant's paper is quite correct.

State of grace - the floor trusses weren't the main parts of the towers absorbing the brunt of the falling block. The lattice-work of thousands of steel beams, and the 47 core columns were tremendously more than enough to arrest a 20-30mph impact by the top 15%. Resistance would have been so overwhelming that the top block would have stopped immediately.

Goodbye, anybody who buys into that crap is beyond anything I can post.

 

[Travis]

So if 12 floors drop onto the floor below that floor is going to resist and be invulnerable because it has 97 floors below it giving it moral support or something?

 

[Christopher7]

Exactly! Bazant made a conservative assumption that is grossly in favor of collapse arrest.

Quite the contrary, he literally stacked the deck in favor of collapse by including all the accumulated debris.

That did not happen.

Yet the calculations show that the structure fails even when a perfect axial load is evenly distributed.

The calculations show that the structure fails even only when a perfect axial load is evenly distributed.

That did not happen.

 

[e^n]

State of grace - the floor trusses weren't the main parts of the towers absorbing the brunt of the falling block. The lattice-work of thousands of steel beams, and the 47 core columns were tremendously more than enough to arrest a 20-30mph impact by the top 15%. Resistance would have been so overwhelming that the top block would have stopped immediately.

You have obviously not done any calculations to support this, and are obviously ignorant of the gigantic amount of force involved when adding momentum.

I'll explain this as I understand it. As far as I am aware we are both laymen here, so there is no reason that I should be able to grasp this while you cannot.

Bazant's model represents the best possible case for building survival. If one floor were to suddenly be removed from the building, the upper floors will begin to fall. If the upper section remains perfectly vertical, every column will experience a purely vertical impact. As these columns were designed to resist vertical force, this will result in them being able to absorb the maximum amount of energy.

If these columns do not have the capacity to resist this force without failing, then no other orientation would fare any better. This is a limiting case which is important because it allows us an insight without having to develop an extremely detailed model and have to deal with complex error analysis.

The results of Bazant's original paper were of course that at best the lower floor had under 1/8th (from memory) of the capacity required to resist even this heavily biased scenario. This is a sure sign that the building would fail in any situation involving the removal of one floor's worth of support.

Before I continue, I expect from your comments that you will express some incredulity here. To rectify this I propose you conduct a simple experiment. Bridge a gap with a number of identical wooden blocks. Place weights upon one of these blocks until the block fails. Divide this weight by 3 (indicating a 'safety factor' of 3) and proceed to drop it on the remaining blocks at heights of 3, 6, 9 and 12 feet. Report back to us with the results. Alternately you could place your hand on the floor and drop a 1kg weight from these heights, although I suspect you will not want to continue after the second test

Bazant's paper was a reasonable attempt at a limiting case, but from comments occuring after it was published, there were some problems found. There were more energy sinks to be considered (crushing concrete to observed sizes, compressing and ejecting air etc) which were not in the original paper. To that end, a more refined paper referred to as BLBG (after the authors, Bazant, Li, Benson and Greening) has been published in a highly reputed, peer-reviewed journal (see Mackey's post above).

There is no evidence that this article was treated in any special way, indeed it has been corrected prior to publication. Your assertion above that anyone with a physics degree must therefore understand that Bazant's paper is rubbish does not hold up to these facts. If this were truly the case, then how do you explain the international organisations and reputable journals publishing and endorsing the 'official story'?

I am not a particularly strong writer, nor am I a degreed engineer, but as I see it the evidence stacks up pretty heavily in favour of a 'natural', gravity powered collapse.

 

[e^n]

Quite the contrary, he literally stacked the deck in favor of collapse by including all the accumulated debris.

That did not happen.

BLBG accounts for this I believe. The equations and values they use are in the paper, you may re-apply these equations with any mass shedding fraction you see fit. Please do this and show us the results.

The calculations show that the structure fails even only when a perfect axial load is evenly distributed.

That did not happen.

The word 'only' does not make sense in this context. As I explain in my post above, Bazant's model represents a boundary condition. There is no mechanism by which more energy can be absorbed by the columns than a perfect axial impact. Any other impact will result in a lower capacity, and therefore if a perfect axial impact results in failure, any other impact must result in failure.

 

[GlennB]

.....monolithic or not, mass will not fall through itself.

We were hoping you would explain this statement. It makes no sense to me. "fall through itself" ???

What you witnessed on 9/11 was demolition. What kind of demolition is what you should be trying to figure out. The pictures I've seen show steel beams being blown hundreds of feet outwards surrounded by huge clouds of pulverized concrete. Nothing was just 'falling down' from gravity. Haven't you read somewhere that the amount of energy expelled didn't equal the amount of energy present? No joke.

My bolding.

Yes, I read it. Jim Hoffman's work regarding so-called pulverisation and "pyroclastic flow", way back on wtc7.net. He got his concepts and figures badly wrong - twice - and abandoned the whole idea.

You seem new to this. Don't get quite so enthusiastic so quickly.

 

[Dave Rogers]

The calculations show that the structure fails even only when a perfect axial load is evenly distributed.

^{[Citation needed].}
Dave

 

[Gravy]

Quite the contrary, he literally stacked the deck in favor of collapse by including all the accumulated debris.

That did not happen.

See e^n's reply, and read the BLBG paper, which addresses this concern in detail.

The calculations show that the structure fails even only when a perfect axial load is evenly distributed.

That did not happen.

Since you believe this to be true, you must have the idea that collapse would not progress if the load was applied eccentrically. Please explain why you think this is so, with reference to physics and engineering principles that aren't pulled out of your ass.

 

[ElMondoHummus]

The calculations show that the structure fails even only when a perfect axial load is evenly distributed.

That did not happen.

Oh, for the love of God... how many times has it been said in this forum that a "perfect axial" impact was the limiting case where such a strike would provide the most resistance, and that any amount of of-axis impact would be a scenario where overall the system requires less energy before collapsing? Saying his paper only applies to perfectly vertical impacts is stupid; that's like saying that removing two or more cards from a house of them cannot cause collapse because the demonstration of the idea only removed one of them. The limiting case demonstrates that collapse happens in all lesser situations, it doesn't limit it to perfect vertical impacts only! On the contrary, that case was used to explicitly demonstrate that other failure modes were possible because the most resistant mode wasn't able to withstand the forces! The reality of the towers collapse was that the impacts were more conducive to collapse than Bazant's model. His was the limiting case, it was not a work that only applied to a single scenario.

Your choice of criticisms demonstrates a refusal to understand the work.

ETA: e^n beat me to it, and with a far better explanation. I suggest you read his post and comprehend how abjectly ridiculous it is to propose that Bazant et. al.'s work only applied to direct vertical impacts. Refusal to do so demonstrates a condition that has progressed far beyond obduracy and settled into outright denial.

 

[Christopher7]

Quite the contrary, he literally stacked the deck in favor of collapse by including all the accumulated debris.
That did not happen.

See e^n's reply, and read the BLBG paper, which addresses this concern in detail.

BLBG paper? I read Bazant's hypothesis.

He did NOT allow for the material ejected outside the building. He has proven a non-existent event. Big wow.

Most of the mass was ejected outside the buildings.

For his theory to have any validity, Bazant must use the actual amount of weight involved or a reasonable estimate.

The calculations show that the structure fails even only when a perfect axial load is evenly distributed.

That did not happen.

Since you believe this to be true, you must have the idea that collapse would not progress if the load was applied eccentrically. Please explain why you think this is so, with reference to physics and engineering principles.

Bazant has done the math that shows the Towers would have collapsed to the ground given the conditions:
1) All the accumulated weight was applied to each successive floor.
2) All the accumulated weight was applied evenly.

That is all he has shown. He has NOT shown how the towers would collapse using the conditions that actually existed.

 

[Heiwa]

So if 12 floors drop onto the floor below that floor is going to resist and be invulnerable because it has 97 floors below it giving it moral support or something?

You have misunderstood Bazant. 2001 Bazant suggested that it was the upper part columns that dropped down and impacted the lower structure columns - shock wave, lower columns broke like spaghetti, upper part columns impacted what remained of columns below again, etc, etc, and WTC 1 collapsed from top down. WTC 1 was knocked on its head! Bazant has since abandoned that stupid idea. The upper part columns evidently misses the lower columns. They only make up 0.13% of the foot print. A little misalignment = no impacts. No knock on the head.

In 2008 Bazant suggests (the BLGB paper) that upper part C drops and crushes the top storey below of part A, which becomes a layer of rubble - part B. Then part C strangely pushes this layer of rubble - part B - down to crush the next storey of part A that becomes more rubble.

Every time a 3.6 m tall storey of part A is crushed 0.9 m of rubble is formed to be added to part B. This is crush down! Forget collapse!

In the end there is 87 m of rubble B between upper part C and lower part A.

To prove this Bazant presents a 1-D model with three lines! Line C (top part - constant length) pushes against line A (WTC below floor 97) and a line B (rubble) is formed that gets longer, while line A gets shorter.

The interaction between these three lines is then described as a differential equation that is easily solved ... and that's the only evidence that part C crushed part A in a global crush down.

In layman's terms - line C knocks on line A and a bit of line A becomes line B. This happens 97 times. Then line A has disappeared and there is only line B that is 1/4 long as line A. Then - POUFF - lines B and C disappear.

Yes, ASCE has peer reviewed the BLGB paper! WTC 1 was just two lines A and C and then C knocked on line A so that it was replaced by line B (rubble) that popped up ... and disappeared. A nice example of NWO physics or structural design/analysis.

OBL apparently knew this weakness of US structural designs and took advantage of it.

In WTC 7 apparently there was a variation. Line A was floors 0-8 and line C was floors 16-47. Line B - the rubble - was already in place - floors 8-16. And suddenly line B of WTC 7 disappeared - POUFF - on 911, and line C dropped at free fall. NIST has confirmed it.

Evidently NIST are not experts on this. That's why they were asked to produce their reports supporting NWO physics. That's the new US standard.

 

[Dave Rogers]

BLBG paper? I read Bazant's hypothesis.

You might want to read up on more recent analysis of the collapse. BLBG refers to the 2008 paper "What Did and Did not Cause Collapse of WTC Twin Towers in New York," by Zdenek P. Bazant, Jia-Liang Le, Frank R. Greening and David B. Benson, which you can find online at http://www.civil.northwestern.edu/p...TC Collapse - What Did & Did Not Cause It.pdf. It gives a more thorough discussion of the mechanics of progressive collapse, including mass ejection.

He did NOT allow for the material ejected outside the building.

BLBG page 14:

For the North Tower, because of its lower initial falling mass, stage (c) dominates, and so an increase in Kout always gives an increase in collapse duration. If Kout is increased from 0.05 to 0.5, the crush-down collapse duration is longer, but not by more than 0.45 s, which still matches the seismic record well enough. For the South Tower, the effect of stage (b) mildly prevails over a considerably long period while effects of stages (a) and (c) are weak. The net result is to lengthen the crush-down duration, but only a little; if Kout is varied from 0.05 to 0.5, the crush-down duration increases by only 0.14 s.​

Most of the mass was ejected outside the buildings.

^{[citation needed]}
Dave

 

[ElMondoHummus]

Bazant has done the math that shows the Towers would have collapsed to the ground given the conditions:
1) All the accumulated weight was applied to each successive floor.
2) All the accumulated weight was applied evenly.

That is all he has shown. He has NOT shown how the towers would collapse using the conditions that actually existed.

(*Facepalm*)

[quote="Why Did the World Trade Center Collapse?—Simple Analysis", Zdenek P. Bazant, F.ASCE, and Yong Zhou]

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. If the building is found to fail under a uniform distribution of the impact forces, it would fail under any other distribution.​

[/quote]

They explicitly state that their model is a boundary condition. They explicitly state that it is the best-case scenario for collapse resistence. Therefore all lesser cases favor collapse even more than theirs does. And yet, you try to state that this work is limited to a single scenario? When it's explicitly stated otherwise?

This is exactly what I mean by outright denial.

 

[R.Mackey]

If you have a physics degree, then you already know Bazant's crap doesn't float. Don't pretend you don't. You would already know that a close model global progressive collapse is impossible. You would already have tried to duplicate it...and you would have failed.

Those on your side already know my degrees, having researched me.

If this were true, then everybody in the world with similar or better training who's ever seen this paper would know it "doesn't float." So that means Dr. Bazant, his collaborators, his students, the reviewers and editors of journals he's published in, those responding to his work and publishing follow-on articles, and everyone citing his work (such as NIST) are also frauds or in on the plot.

Furthermore, these articles are published in mainstream journals, read by literally hundreds of thousands of professionals -- the ASME has a membership of over 125,000 -- and used in influencing roughly 600 building codes, which are in turn used by countless millions of professionals. Yet none of these individuals have found the obvious problems in his papers. Taking an awful chance, distributing copies of their journals to their members, aren't they? Or putting copies in libraries?

But let's not stop there. These papers are also available for free download. Even the dumbest members of the Truth Movement can find them. Who knows how many more people have found them? Yet, strangely, nobody has put forth a mathematical refutation. The most pointed critique anyone has produced is Gregory Urich, and he has since left the Truth Movement.

So, let's review. Either countless thousands and thousands of experts are in on the plot, or inexplicably choosing to go along with it, countless millions who are aware of this work find it perfectly unremarkable, and the obvious lie remains in plain sight for anyone in the world to read...

... or a lone Internet joker who literally signed up yesterday, and has presented no calculations of any kind, is a braggart and a liar.

Anyone who chose the first alternative, see me after class for make-up assignments. Hope you didn't have any plans this quarter.

 

[Hokulele]

Well, let's experiment, hokulele. Take 10 cinderblocks and mortar eight of them together one on top of the other. Take the top two and mortar them together to form 'your block'. Raise the top two up about 10 feet and drop them down on the lower eight and observe what happens.

Let's do math instead. Calculate the potential energy of 2 CMU's at a height of 10 feet. Calculate the kinetic energy of those 2 after they have fallen 2 of those feet. Calculate the remaining potential energy of those two.

Now, calculate the potential energy of the top portions of WTC 1 and 2 (they are different). Calculate the kinetic energy of the same after a drop of 3 meters. Calculate the remaining potential energy.

Congratulations! You have now completed the first step towards understanding and verifying the results from Bazant's papers. Once you have shown your work, we will move on to step two.

 

[ElMondoHummus]

If you have a physics degree, then you already know Bazant's crap doesn't float. Don't pretend you don't. You would already know that a close model global progressive collapse is impossible. You would already have tried to duplicate it...and you would have failed.

Well, let's experiment, hokulele. Take 10 cinderblocks and mortar eight of them together one on top of the other. Take the top two and mortar them together to form 'your block'. Raise the top two up about 10 feet and drop them down on the lower eight and observe what happens.

Do the lower eight turn to dust? Do the top two blocks fall straight through the others to the ground? Do they bounce off? Do they just stop with a little damage? This experiment is without any steel at all, but I think you get the idea.

Edited to add:

Where's Bazant? I'm sure he tried this!

Who in God's name is this guy? And why's he resurrecting the same mistakes that every other truther has made all over again? Mindlessly repeating a point is not the same thing as proving it!

And can someone other than Gregory Ulrich come up with a critique that's actually relevant and accurate? All I ever see are Chris's absurdities about scope, Heiwa's bizzare "bounce" propositions, and plain straight out unsupported blather like KreeL's post above. Will someone in the truth movement please attempt to build a coherent critique of the material at some point?