Moderated Continuation - Why a one-way Crush down is not possible

[Dave Rogers]

I think you are referring to a guy named Christophera in regards to this imaginary documentary you keep bringing up. He claimed there was a documentary that showed the core was concrete.

No, I am sure that you claimed to have seen a documentary that you said had someone admitting it was a demolition. Are you denying this?

If I am wrong I will apologize.

You're not wrong, and Tony doesn't seem to have a terribly good memory.

Finally, you complain that I discuss the obvious controlled demolition of Bldg. 7. I have never met anyone who has seen that collapse call it anything but. I also told you via e-mail that I watched Larry Silverstein use the actual words "Bldg. 7 was a controlled demolition for safety reasons" on a History Channel show called History's Business in late 2002, so I absolutely know I am right about that and none of yours or Popular mechanics non-engineering editors can say different. I tried to get a copy of that show when I realized 911 wasn't what we were told it was last year, and the History Channel told me that series is not publicly available. Interesting. No need to be suspicious though as you will simply say Bldg. 7 wasn't a controlled demolition.

Feel free to follow the link back to the original post.

Dave

 

[funk de fino]

I guess Tony will explain all and tell us why he ran away from this one?

Imaginary documentaries indeed.

Thanks Dave.

ETA - Could be in my sig if this carries on.

 

[tfk]

You guys may decide to do the calculation on whether or not it would have stood on its own. My gut tells me "no".

But I think that it's a waste of time.

I'm a bit more pragmatic than that.

I am DAMN sure that the lattice structure would NOT stand with approximately 200,000 tons of massive pieces of rubble being flung at its base from a height of about 1300 feet.

Except perhaps a small piece. For a few seconds. Before falling straight down.

Just my opinion.
(As informed by - and MODIFIED by - the video evidence, of course...)

Tom

 

[Grizzly Bear]

I don't think the calculations serve much purpose other than to show that they wouldnt've stood alone even if they were in pristine condition following the collapse of the floors. It's a bit worse for their integrity after suffering the shock damage from the collapse, and it's clear from the videos what the progressive collapse did to the core structure. Although knowing the process which Szamboti used to determine his conclusions is a bonus

 

[triforcharity]

Bill,

Lets not get started on CD. I personally can pick that apart like it was a lego house. More like, go stomping through it like King Kong on Tokyo!!

 

[Heiwa]

.

.
Why are you unable to quote your own paper correctly?

Your "WTC1 - the Case for Collapse/Crush down Arrest" says:

"It is suggested that the first crush down can be initiated by a 0.5 m drop of part C, thus the initial potential energy, PE
0, applied is 0.5 x 54.06x10⁶ x 9.82 = 265.44x10⁶ J." (PE = h m g)

This is, of course, some of your typical sloppiness.

The Kinetic Energy that the upper block gained in its fall is NOT determined by "what energy would crush an object below". Difficult to believe that you could write and then publish something this ill-considered.

As you know, the KE that it has gained is equal to the PE lost, which is determined by its mass & the height that it HAS fallen. Which in this case is about 3.6 meters. So the right answer (using your mass number) is PE is 3.6 m x 54x10⁶ Kg x 9.81 m/sec² = 1.9 GJ.

And yet you produce 1 GJ here. Sloppy.
.

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Bad assumption. But it is a starting point.
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Wrong. There are about 100 columns that can punch holes. 50 up & 50 down. If you'd paid attention in class, instead of daydreaming of your impending glory, you would have gotten this right.
.

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Baseless assertion. "Fail"

Tell me your assumptions. Which parts are undergoing deformation, what are their loads & deflections.
Show that you haven't blown some trivial number that would not make your elastic absorption be 0.001 GJ.
.

.
Baseless assertion. "Fail"
.

.
I would like to point out that your analysis makes zero sense.
IF, as you say, "the columns punch holes in the concrete floors" (as is certainly true), well then the concrete floors did NOT arrest the fall. Unless you contend that the 50,000 Metric ton upper block can stand on air.

If it did punch holes, then you must consider the NEXT group of parts that comes into contact. If that one is shown to fail, then you must consider the NEXT one after that. And so on.

And you must continue this process UNTIL you come to some parts that do NOT fail. Then, AND ONLY THEN, can you say that the collapse will be arrested.
___

Thus far, your high-falutin' Structural Damage Assessment rates an "F".

I've been trying to help you raise your grade. You don't seem to want to do the work necessary.

But this is the part that really matters.

You must CORRECTLY calculate how much kinetic energy the upper block has acquired at each collision.
You must identify the parts that fracture, and calculate how much energy that they can absorb.
... [Big hint here: Do not consider the columns to be 1 story high. This will give you wrong answers.]
You must identify the parts that ultimately do NOT fracture. And show that their total energy absorption capacity is greater than the remaining kinetic energy in the upper block.

Then, and only then, can you say that the block will stop.

I am running out of patience with you, young man. Your constant antics in class are holding everyone back.

Tom

Thanks for reading my papers. Yes, if the free fall drop is 3.6 m and the associated mass is 54 000 000 kgs then the free energy is 1.9 GJ. I just use better figures. But there is no evidence that any mass free fell any distance!

You see, if a structure consists of two parts C and A and C and A are connected by 280+ element, upper part C can never free fall on lower part A.

Or, can you provide evidence to the contrary?

Anyway, if C impacts A, both parts C and A first deform elastically, while part C is decelerated (the jolt!). You agree?

This deformation, compression, transforms the energy into heat! Both parts C and A warm up a little. And that energy is then 'lost' and cannot produce any further damage.

If local elements in parts C and/or A fail, more energy is transformed into heat and is then 'lost'. Of course, local failures may cause parts to displace, so that more potential energy is released, but what happens then?

Yes, at new contacts the structure deforms again elastically, the moving element is decelerated and more energy is lost as heat.

And that's Why a one-way Crush down is not possible! When any structural element fails and produces a displacement/new contact there is elastic compression, and this goes on and on and on and on ... and the destruction is very soon arrested.

Bazant completely ignores the multiple elastic compressions that are associated with a one-way crush down/multiple contacts and that always arrest the local destruction.

Do this test! Jump in your bed and measure the temperature of the springs in the mattress. The temperature will slowly increase! Every time you contact the mattress, potential energy is transformed into heat that warms up the mattress. It is quite fun to jump on a mattress. It started off my career to debunk the OCT of 911.

 

[boloboffin]

You have no idea.

Actually I do, but as an aside, the person with no idea is better than a person with the wrong idea.

Bracing doesn't just mean diagonal bracing. The horizontal beams at every floor are braces to support the columns laterally and keep the slenderness ratio down so local buckling does not occur.

I have never in my life seen someone who claimed to be an engineer argue against the necessity of diagonal bracing for the stability of a structure, particularly a structure 110 stories high. You are a fool, Mr. Szamboti.

Where are your calculations to back what you say here Joe?

My dad is Joe. I'm Joseph. You don't know me well enough to call me anything else other than Bolo Boffin, anyway.

I don't need calculations to back up what I say. The perimeter columns handled all lateral loads. They were the diagonal bracing for the core columns. If you don't understand that, you're beyond help. You've allowed your ideology to influence your understanding of physical principles.

Are you still getting enough sleep? Eight hours a day, Mr. Szamboti.

Another case of foot in mouth disease here. There is an old saying that if you don't know much about a subject it is better to keep your mouth shut and let people just think you don't know much about it, rather than saying something and removing all doubt.

You and Alienentity have removed all doubt as to your abilities to comment on the engineering aspects of this subject.

I'll leave you to your glass house, Mr. Szamboti.

 

[Justin39640]

This deformation, compression, transforms the energy into heat! Both parts C and A warm up a little. And that energy is then 'lost' and cannot produce any further damage.

wouldnt gravity add energy to falling parts?
or do they just freeze in mid air once they deform?

 

[Grizzly Bear]

Do this test! Jump in your bed and measure the temperature of the springs in the mattress. The temperature will slowly increase! Every time you contact the mattress, potential energy is transformed into heat that warms up the mattress. It is quite fun to jump on a mattress. It started off my career to debunk the OCT of 911.

For the record it's against forum rules to advocate doing voluntary bodily harm... The disclaimer to this should read: "have emergency personel on standby when the bed frame snaps"

(image rehosted on imageshack to avoid hotlinking issues)

 

[aggle-rithm]

I would agree that these discussions are a waste of time and energy. It has been irrefutably shown that there is not a chance that those buildings collapsed due to natural causes and a new investigation should have been initiated quite some time ago.

Of course they didn't collapse from natural causes. There was a freaking PLANE CRASH.

Where have YOU been?!?

 

[Heiwa]

wouldnt gravity add energy to falling parts?
or do they just freeze in mid air once they deform?

Reason why parts fall is gravity. Topic is what happens when a falling part C contacts a part A connected to ground and stops falling.
Some fools suggest that C one-way crushes down A, while I suggest it is impossible. Try to prove me wrong!

 

[Dave Rogers]

Anyway, if C impacts A, both parts C and A first deform elastically, while part C is decelerated (the jolt!). You agree?

This deformation, compression, transforms the energy into heat! Both parts C and A warm up a little. And that energy is then 'lost' and cannot produce any further damage.

This is pure scientific illiteracy. If the deformation is purely elastic, no heat can be generated, by definition. If heat is produced, then inelastic deformation is taking place, and this equates to structural damage. If sufficient structural damage occurs, collapse continues.

If local elements in parts C and/or A fail, more energy is transformed into heat and is then 'lost'. Of course, local failures may cause parts to displace, so that more potential energy is released, but what happens then?

Yes, at new contacts the structure deforms again elastically, the moving element is decelerated and more energy is lost as heat.

And this is the unevaluated inequality fallacy. Without calculating how much energy is absorbed and how much potential energy is released, you cannot tell which is greater. If the energy released is greater than the energy absorbed, collapse continues. And if, in every such collision, a very large excess of potential energy is released, collapse can be predicted to be total.

You talk about what you claim Bazant ignores, but you continue to ignore the vast excess of gravitational potential energy over that required to collapse the structure. Except, of course, when you make up spurious numbers to give the false impression that it doesn't exist.

Dave

 

[Heiwa]

This is pure scientific illiteracy. If the deformation is purely elastic, no heat can be generated, by definition. If heat is produced, then inelastic deformation is taking place, and this equates to structural damage. If sufficient structural damage occurs, collapse continues.



And this is the unevaluated inequality fallacy. Without calculating how much energy is absorbed and how much potential energy is released, you cannot tell which is greater. If the energy released is greater than the energy absorbed, collapse continues. And if, in every such collision, a very large excess of potential energy is released, collapse can be predicted to be total.

You talk about what you claim Bazant ignores, but you continue to ignore the vast excess of gravitational potential energy over that required to collapse the structure. Except, of course, when you make up spurious numbers to give the false impression that it doesn't exist.

Dave

Evidently, if a connection of an element fails, all compressed connections below this element evidently also decompress and displace upwards ready for a new contact; some stored elastic energy is released again ready to decelarate any elements dropping on it.

 

[phunk]

If the entire structure below the collapse zone compresses then bounces back, then while the top of part A is rebounding it INCREASES the force of the impact of part C into part A. This doesn't make part A stronger, it just makes the impact harder.


ETA: Not that I believe that's what happened, just pointing out that Heiwa's theory is silly.

 

[bill smith]

.
Bill,

You gotta stop this. It's just not fair.

YOU... proved ... BAZANT ... wrong ...??!!

Sure thing, billy. And after you're done with your proof, you're going to put on your jammies & cape & fly into space to push aside the asteroid that is approaching the earth. And then have a nice evening with Lois Lane... Don't forget to wear your glasses so that she doesn't recognize you ...

Heck, bill. Even the chihuahua is in convulsions of laughter, pointing his paw at your post. Kibbles & Bits are flying out of his nose...

"Hey, Brutus, Watch it. The keyboard..."

Wait a second, the Chihuahua wants to type something:
The Chihuahua says:


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Darn it, bill. The damn dog was laughing so hard while he was typing that now I'm wiping Purina Chihuahua Chow off my screen.

Gross...

Bill, I DO appreciate your attempt at farce. At absurdity. At burlesque. But some of the "opposing thumb-less" members of my household are just not ready for it.

Please refrain from this in the future. The clean up is a bear...

Tom

PS. "No, Brutus. "A bear..." is just an expression. There is no REAL bear ... Aw, DAMN!! The carpet..!!!"

PPS. Thanks a LOT, bill...

We always knew that that Bazant was pulling all our legs but that was difficult to establish beyond doubt in he eyes of the public when we had an enormous body of people who just said 'no'and were prepared to keep saying 'no' under any and all circumstances.
So it's nice to have participated in the coalition that finally put the Bazant myth of the 'rigid upper part C' to rest for good using introvertible video evidence. 'No' is no longer a realistic option for you guys and you will have to attenuate your position to accomodate this new empirical data.

Now you must show how some sticks and stones crushed 97 floors of WTC1 down to the ground. I wish you luck.

You should get a real dog like mine. He's a long nosed long tailed short haired Irish Wolfhound. His name is Ferdia. A pure killer when he wants to be.

 

[aggle-rithm]

Evidently, if a connection of an element fails, all compressed connections below this element evidently also decompress and displace upwards ready for a new contact; some stored elastic energy is released again ready to decelarate any elements dropping on it.

...in your mind.

 

[aggle-rithm]

If the entire structure below the collapse zone compresses then bounces back, then while the top of part A is rebounding it INCREASES the force of the impact of part C into part A. This doesn't make part A stronger, it just makes the impact harder.


ETA: Not that I believe that's what happened, just pointing out that Heiwa's theory is silly.

Exactly...he talks about decelerating like it's a good thing, but in physics terms what he is describing is acceleration (change in velocity), which results in huge amounts of force being applied.

 

[tfk]

Thanks for reading my papers.

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I've tried several times. Every time I reach the 10th blatant error, I find it impossible to continue.
Usually, that limits me to about 3 paragraphs at a sitting.
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Yes, if the free fall drop is 3.6 m and the associated mass is 54 000 000 kgs then the free energy is 1.9 GJ.

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That is correct.

So we agree:
Your 1 GJ number that you provided earlier was wrong.
Your 265 MJ number (based on 0.5 meter fall) in your paper is wrong.

The right number (based on free fall assumption) is 1.9 GJ.
.

I just use better figures. But there is no evidence that any mass free fell any distance!

You see, if a structure consists of two parts C and A and C and A are connected by 280+ element, upper part C can never free fall on lower part A.

Or, can you provide evidence to the contrary?

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The conservation of energy (∆KE = -∆PE) assumes free fall.

A true motion analysis would likely show a gradually increasing acceleration, just like WTC7. NOT instant G (or 0.7G), but a gradually increasing acceleration (while individual structures snapped and buckled) up to a final value of about ~0.8G. (Note that, if the average over the entire interval was 0.7G, then the final value of the instantaneous acceleration will be greater because the earlier instantaneous values were less.)

There is clear evidence that this happened in the video.
.

Anyway, if C impacts A, both parts C and A first deform elastically, while part C is decelerated (the jolt!). You agree?

This deformation, compression, transforms the energy into heat! Both parts C and A warm up a little. And that energy is then 'lost' and cannot produce any further damage.

...

And that's Why a one-way Crush down is not possible!
...

.
... blah, blah, blah ...

And this is why you are a lousy engineer, Heiwa. You are unable or unwilling to focus on the questions asked.

I didn't ask ANY of this. And NONE of it is relevant in the slightest.

I asked specific questions.

Now, how about answering my questions.

1. What are the weak link components on Floor 98 that would have to break in order for the collapse to continue?
2. What are the components of floors 96 thru 100 that actually DO break when the columns on floor 98 buckle?
3. What are the components of floors 96 thru 100 that actually DO break when Part C crashes into Floor 98?
4. How much energy would it take to break them? (In Joules, please.)

Please answer the above questions. And no others.

Tom

 

[beachnut]

We always knew that that Bazant was pulling all our legs but that was difficult to establish beyond doubt in he eyes of the public when we had an enormous body of people who just said 'no'and were prepared to keep saying 'no' under any and all circumstances.
So it's nice to have participated in the coalition that finally put the Bazant myth of the 'rigid upper part C' to rest for good using introvertible video evidence. 'No' is no longer a realistic option for you guys and you will have to attenuate your position to accomodate this new empirical data.

Now you must show how some sticks and stones crushed 97 floors of WTC1 down to the ground. I wish you luck.

You should get a real dog like mine. He's a long nosed long tailed short haired Irish Wolfhound. His name is Ferdia. A pure killer when he wants to be.

Why do you insist on posting proof you have no idea what you are talking about? You have failed to support your delusions with calculations, facts and evidence.

You should get a real education before posting about engineering topics.

 

[Heiwa]

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I didn't ask ANY of this. And NONE of it is relevant in the slightest.

Tom

Elastic/inelastic compression at contact is very relevant to establish where the contact forces are, energy applied/transformed and what elements will fail, if any.

It seems we agree, that if part C contacts part A, part A also contacts part C and that you finally agree that part C will be subject to local failures!

Bazant disagrees! Part C will, for unclear reasons, not be subject to local failures and Bazant suggests that it is superfluous to discuss that detail.

Detail? According Bazant, it is part C, undamaged, that one-way crushes part A. Never heard of before/after 911 but a normal phenomenon according Bazant ... that cannot be discussed. Superfluous!

What is part C? Well, it is mainly pre-fab perimeter wall assemblies and floor/truss sections bolted together around a fairly solid core. Most elements of part C are just bolted together (like part A below).

Bazant suggests that part C is a rock solid, rigid block of some sort, but we know better. It is a very flexible assemby of elements as just described. Like part A.

So when these two structural parts C and A, flexible, quite fragile actually, collide, you can be sure that part C breaks into pieces; the floor/truss sections are like paper, the wall perimeter assemblies will just drop off outside. If you believe that these bits and pieces then can one-way crush down part A (and the core !!!!) you are kindly requested to demonstrate it. And prove my Axiom wrong!