Physics of 9/11...

reply to post by Joey Canoli

What pancake theory would that be? The "OS" doesn't involve a pancake initiation, it was ruled out by NIST. FEMA proposed that as a possibility.

I'm confused, you then go on to describe a pancake collapse. Whatever fit's your argument at the time?

At the moment of impact, this is correct. What happens though after the floors are destroyed? Both of them are accelerated by gravity and fall onto the next floor below.

You have just described pancake collapse. Why don't you explain how you think the columns failed? I'm also curious to know what the standard debunker explanation is now for the "squibs", as pancaking used to be this explanation, courtesy of Popular Mechanics.

And most people realize that without initiation, there is no collapse progression, making initiation the most important factor for structural engineers to avoid.

This does not justify leaving collapse progression out of the OS. What have you got against people wanting to know more about what happened? All we ask is for another (more thorough, independent and professional) investigation.

This is how buildings are designed. Are you calling the effort put into these designs "theoretical" also then, and of zero real value?

Now we have someone with no experience in structural design trying to tell someone with real world structural design experience how buildings are designed.

No. They use accepted design facts and city/county/state/fed codes.

Yes I know, I'm the one who does this for a living and have mentioned codes in most of my previous posts. I know it is difficult for you to find an arguing point but please stop quoting me out of context to try to make me sound silly.

This is called quality assurance. Not experimentation.

Actually, in masonry design, if the engineer wishes to use a value higher than 12Mpa for the compressive strength of the blocks he must obtain this value via experimentation on a sample of the blocks to be used before any design takes place.

I CAN agree to this. The towers were in fact subjected to wind tunnel tests, satisfying your point. Even though there is a provision in the NYC building code that makes this unnecessary.

You've completely gone of on a tangent here, trying to relate it to some context other than the point I was making.

And since I've proven you to be dishonest as to where the experimentation alters the way in how buildings are actually designed, everyone can see that you're tilting at windmills.

All you have proven is your ignorance and that you liken yourself to some sort of expert when you have no experience in the structural engineering industry.






[edit on 19-7-2010 by Azp420]

Originally posted by Azp420

I'm confused

Obviously.

you then go on to describe a pancake collapse. Whatever fit's your argument at the time?

Collapse initiation.

Collapse progression.

2 different things entirely.

You have just described pancake collapse. Why don't you explain how you think the columns failed?

NIST covered the initiation: impact damage, moderate temp (~250C) creep, load transfer, floor sagging, etc. What do you need explained?

This does not justify leaving collapse progression out of the OS. What have you got against people wanting to know more about what happened?

Nothing. read Bazant. Refute it if you think he's wrong. You'll be the first.

All we ask is for another (more thorough, independent and professional) investigation.

Yes, we know. Truthers are uneducated dolts that don't understand the process, however. They think that stomping their feet and demanding a new investigation that satiffies their incredulity will get them somewhere.

Now we have someone with no experience in structural design trying to tell someone with real world structural design experience how buildings are designed.

So you're claiming experience? Coming from a guy that proposes comparing the collapse to am horizontal impact........ that's a real laugher.

please stop quoting me out of context to try to make me sound silly.

You don't need my help, Mr let's-compare-it-to-a-horizontal-impact.

Actually, in masonry design, if the engineer wishes to use a value higher than 12Mpa for the compressive strength of the blocks he must obtain this value via experimentation on a sample of the blocks to be used before any design takes place.

Yeah, like I said, quality assurance, since the compressive strength may vary between manufacturers.

You've completely gone of on a tangent here, trying to relate it to some context other than the point I was making.

Nope. You've taken an experiment on the entire building and compared it to small scale engineering - like buckling loads and moderate temp creep. These most definitely experimented on before any building is built.They are known and understood values.

BTW, you're still avoiding Bazant's calcs, etc.

We all know why. Because you cannot refute one iots of it.

All you have proven is your ignorance and that you liken yourself to some sort of expert when you have no experience in the structural engineering industry.

Nope. We can all see your bluster. When provided the calcs from Bazant, and a technical paper to review, you have avoided it like the plague.

Originally posted by Azp420

I didn't say that, I said steel can fail at 20C.

And you have also studiously avoided the engineering evidence that Bazant has referred to, proving that truthers are either wrong, or lying when they (like ANOK) say that steel can't fail at 250C.

Again, you seem to just be making up the context to fit whatever point you are trying to make.

The context is WTC.

Regardless of what adjective some fire fighters used

So you disregard what they say then?

Are they wrong, or lying?

Man up and tell us what you think of their statements.

the fires in WTC7 were no way comparable in size with some of the raging infernos survived by other high-rise steel structures in history.

Like the Madrid building? Where the entire building is the size of the tower cores?

It's all relative, but I know you like to argue semantics.

Nope. I like to argue that the firefighter's opinions are more releveant then a truthers opinion, since they were there, and you were not.

Allow me to quote from the link to the equations provided. Bazant does not seem to be under the same illusions you are.

Finally, a reference to the paper.

I notice that you have zero alternate values.

Stop trying to mislead everyone that doesn't have the time or expertise to review Bazant's calculations. He has come up with an approximate theoretical model to describe a possible mode of collapse and nothing more.

And that model would be the most advantageous to halting the collapse. Yet, it doesn't.

I will state again that you cannot come up with a hypothesis, derive some theoretical calculations, estimate values for variables instead of using experimentation, then proudly state that you have proven your hypothesis. Most people on here know that is not good science.

What theoretical calcs are those again? You mean the ones based on engineering facts and forensic analysis?

You provided me with the calcs to review but nowhere in the paper does it show how most of the calcs were derived.

References
[1] Baˇzant, Z.P. (2001). “Why did the World Trade Center collapse?” SIAM News (Society for
Industrial and Applied Mathematics) Vol. 34, No. 8 (October), pp. 1 and 3 (submitted Sept. 13,2001.
[2] Baˇzant, Z.P., and Becq-Giraudon, E. (2002). “Statistical prediction of fracture parameters of
concrete and implications for choice of testing standard.” Cement and Concrete Research 32 (4),
529–556.
[3] Baˇzant, Z.P., and Cedolin, L. (2003). Stability of Structures: Elastic, Inelastic, Fracture and
Damage Theories, 2nd ed., Dover Publications (catalog No. 42568-1), New York.
[4] Baˇzant, Z.P., Le, J.-L., Greening, F.R., and Benson, D.B. (2007). “Collapse of world trade center
towers: what did and did not cause it?” Structural Engrg. Report 07-05/C605c, Northwestern
University, Evanston, Illinois.
[5] Baˇzant, Z.P. and Le, J.-L. (2008). “Closure to “Mechanics of Progressive Collapse: Learning from
World Trade Center and Building Demolitions” by Zdenˇek P. Baˇzant and Mathieu Verdure ”,
Journal of Engineering Mechanics, ASCE 134, 2008; in press.
[6] Baˇzant, Z.P., and Planas, J. (1998). Fracture and Size Effect in Concrete and Other Quasibrittle
Materials. CRC Press, Boca Raton and London.
[7] Baˇzant, Z.P., and Verdure, M. (2007). “Mechanics of Progressive Collapse: Learning from World
Trade Center and Building Demolitions.” J. of Engrg. Mechanics ASCE 133, pp. 308–319.
[8] Baˇzant, Z.P., and Zhou, Y. (2002). “Why did the World Trade Center collapse?—Simple analysis.”
J. of Engrg. Mechanics ASCE 128 (No. 1), 2–6; with Addendum, March (No. 3), 369–370
(submitted Sept. 13, 2001, revised Oct. 5, 2001).
[9] Charles, R. J. (1957).”Energy-size reduction relationships in comminution” Mining Engrg. 9,
80–88.
[10] Cunningham, C.V.B. (1987). “Fragmentation estimation and the Kuz-Ram model—four years
on.” Proc., 2nd Int. Symp. on Rock Fragmentation by Blasting (held in Bethel, Connecticut),
W.L. Fourney & R.D. Dick, Eds., SEM, pp. 475-487.
[11] Davis, D.R., and Ryan, E.V. (1990). “On collisional disruption: experimenal results and scaling
law” ICARUS. 83, 156-182.
[12] Frost, H. J. and Ashby, M.F. (1982). Deformation-Mechanism Maps The Plasticity and Creep of
Metals and Ceramics. Pergamon Press (Sec. 8).
[13] Genc, O., Erg¨un, L., and Benzer, H. (2004). “Single particle impact breakage chacterization of
materials by drop testing” Physicochemical problems of Mineral Processing. 38, 214-255.
[14] Hart, F., Henn, W., and Sontag, H. Multi-story buildings in steel Cambridge, UK: Univeristy
Press, 1985.
[15] Kausel, E. (2001). “Inferno at the World Trade Center”, Tech Talk (Sept. 23), M.I.T., Cambridge.
[16] Kim, W.-Y., Sykes, L.R., Armitage, J.H., Xie, J.K., Jacob, K.H., Richards, P.G., West, M.,
Waldhauser, F., Armbruster, J., Seeber, L., Du, W.X., and Lerner-Lam, A. (2001). “Seismic
waves generated by aircrafts impacts and building collapses at World Trader Center, New York
City.”EOS, Transaction American Geophysical Union, Vol 82, 47, 565-573.
[17] Levy, M., and Salvadori, M. (1992). Why buildings fall down? W.W. Norton, New York.
[18] Munson, B.R., Young, D.F., and Okiishi, T.F. (2006). “Fundamentals of Fluid Mechanics,” 5th
ed., J. Wiley, Hoboken, NJ.
[19] NIST (2005). Final Report on the Collapse of the World Trade Center Towers. S. Shyam Sunder,
Lead Investigator. NIST (National Institute of Standards and Technology), Gaithersburg, MD
(248 pgs.)
[20] Ouchterlony, F. (2005). “The Swebrec function: linking fragmentation by blasting and crushing.”
Mining Technology 114 (March), pp. A29–A44.
[21] Schuhmann, R. Jr. (1940). “Principles of comminution, I. Size distribution and surface calculation”.
The American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Technical
Publication 1189.
[22] White, F.M. (1999). Fluid Mechanics, 4th ed., WCB/McGraw-Hill, Boston (p. 149).
[23] Wierzbicki, T. and Teng, X. (2003). “How the airplane wing cut through the exterior columns of
the World Trade Center.” J. of Impact Engrg. 28, pp. 601–625
[24] “World’s tallest towers begin to show themselves on New York City skyline.” Engeering News
Record, 1/1/1970.
[25] Zeng, J.L., Tan, K.H., and Huang, Z.F. (2003). “Primary creep buckling of steel columns in fire.”
J. of Construction Steel Research 59, 951–970.

By the way, if gamma did in-fact = 0.7, that means 70% of the kinetic energy per unit height is dissipated by comminution of concrete floor slabs. A collapsing structure cannot dissipate 70% of its kinetic energy while remaining close to acceleration. Something is very wrong somewhere in the model.

A fine truther style refutation there. No facts. Nothing.

Just a statement.

You'll go far on ATS....

If you have ruled out pancake collapse

At initiation, as offered by FEMA, yes, ruled out.

Progression? No.

it doesn't matter if they fell on the floors.

LMAO.

Something produced large enough forces to cause the columns to fail.

Plane impacts and fire damage led to initiation.

During progression, stuff would have fallen on the core floors a,d broken their connections. this eliminates the core column bracing. So the core columns break easily at their connections.

This is what makes stuff falling on floors important, and your above statement a laugher.

Yes, it is the critical part if you want to keep attention away from the smoking gun.

Funny, but reading some old threads, there was an engineer truther named Griff that agreed 100% with NIST and Bazant. He agreed that once initiated, the collapse had zero chance of arresting. He hung his cap on thermxte attacking the floor connections, since he knew that thermxte has never been demonstrated to work on a vertical column.

At least that made some sense.

I've seen nothing from you that even comes close to approaching that strangely odd combo of delusions, while still trying to reman rational.

I have zero doubt who's correct about the collapse progression.

[edit on 19-7-2010 by Joey Canoli]

reply to post by Joey Canoli


Reading this discussion has been interesting to say the least. I was wondering if there has been discussion about Anders Björkman and his response to Bazant. here is the link,

heiwaco.tripod.com...

Originally posted by dudly
reply to post by Joey Canoli

 

Reading this discussion has been interesting to say the least. I was wondering if there has been discussion about Anders Björkman and his response to Bazant. here is the link,

heiwaco.tripod.com...

.. and don't be fooled by Björkman's repeatedly calling it a 'paper', it is in fact the equivalent of a letter to the editor.

reply to post by Joey Canoli

And you have also studiously avoided the engineering evidence that Bazant has referred to, proving that truthers are either wrong, or lying when they (like ANOK) say that steel can't fail at 250C.

That is a discussion you are having with other members, not me.

The context is WTC.

The context is not WTC, the context is the size of the fires in Building 7 compared with the size of fires survived by similar sized steel structures throughout history.

So you disregard what they say then?

Are they wrong, or lying?

Man up and tell us what you think of their statements.

I don't think they are "wrong" or lying at all. You obviously have no idea what I mean when I talk about relativity regarding the fires in 7. The fire fighters can use whatever adjective they want to describe the size of the fires, such as "large", and that is probably true compared with the size of fires these guys typically are called out to. When you compare it to the size of fires survived by similar sized steel structures throughout history however, the fires in 7 could be described as "small" by comparison. It is how our language works. It is like saying "how long is a piece of string?" or in this case "that's a long piece of string." It's all relative, hopefully you can understand that concept now. I didn't think I would have to keep explaining this so many times.

Like the Madrid building? Where the entire building is the size of the tower cores?

I was thinking more along the lines of the 44 Story Mandarin Oriental Hotel Building in Beijing, but there are numerous examples.

Nope. I like to argue that the firefighter's opinions are more releveant then a truthers opinion, since they were there, and you were not.

Once you understand the concept I once again described above, you will see that this comment is rendered irrelevant.

I notice that you have zero alternate values.

Maybe you didn't get the point I was making. Nobody can produce accurate values without experimentation, even Bazant acknowledges this. His own words were

the precise value of this coefficient would be extremely difficult to determine theoretically.

It would be irresponsible of me to improperly produce an alternative value, and I am not about to carry out the experimentation.

A fine truther style refutation there. No facts. Nothing.

Just a statement.

It is my professional opinion. Anyone with a basic understanding of physics (specifically conservation of energy principles) can see that if 70% of the kinetic energy is dissipated each time a floor impacts, there is no way near enough energy to maintain a free-fall (or anything close to) acceleration. To achieve a free-fall (or anything close to) acceleration, all the gravitational potential energy must be converted to kinetic energy and remain as kinetic energy. As soon as large amounts of kinetic energy are lost, the mass should decelerate (again, like in the OP video, this is where we should see jolts). This is a very basic concept and shouldn't need a link to a scientific paper full of calculations to prove it. Do you disagree with this concept?

LMAO.

Lol.

reply to post by Joey Canoli

During progression, stuff would have fallen on the core floors a,d broken their connections. this eliminates the core column bracing. So the core columns break easily at their connections.

This is what makes stuff falling on floors important, and your above statement a laugher.

But we did not see columns sticking up in the air above the wave of destruction. You say that the floors pancaked during progression, leaving the columns unbraced to collapse under their own self-weight (I assume, you were a bit unclear as to what actually produced the forces to cause them to fail). If this was the case then those columns would have been able to support themselves unbraced for significant heights above the wave of destruction. We also should have been able to see very long lengths of columns throughout the rubble. This is one of the main flaws in the pancake progression theory.

I've seen nothing from you that even comes close to approaching that strangely odd combo of delusions, while still trying to reman rational.

Switching to the personal attacks tactic now out of frustration?

Stop trying to mislead everyone that doesn't have the time or expertise to review Bazant's calculations. He has come up with an approximate theoretical model to describe a possible mode of collapse and nothing more.

And that model would be the most advantageous to halting the collapse. Yet, it doesn't.

You have been claiming that Bazant's model "proves" the hypothesis that plane impacts and jet fuel brought down the towers in the manner displayed. I'm saying that an approximate model can't prove any hypothesis in diligent science. I'm not suggesting the collapse should have been halted either. I am merely supporting the OP video in that there should have been deceleration jolts as each floor impacted the next, and that there should have been no way near free-fall acceleration.

[edit on 21-7-2010 by Azp420]

reply to post by Joey Canoli

I'm confused

Obviously.

Ah, keeping up the quote me out of context to make me look silly tactic? Good job.

Nothing. read Bazant. Refute it if you think he's wrong. You'll be the first.

I can name 1226 other architects and engineers that refute it. Most probably don't frequent this site though.

Yes, we know. Truthers are uneducated dolts that don't understand the process, however. They think that stomping their feet and demanding a new investigation that satiffies their incredulity will get them somewhere.

Since when did acquiring an engineering degree make someone an uneducated dolt? Or this this the personal attack tactic?

So you're claiming experience? Coming from a guy that proposes comparing the collapse to am horizontal impact........ that's a real laugher.

Yes, real world structural engineering design. It is comparable if a force is applied at each floor.

Yeah, like I said, quality assurance, since the compressive strength may vary between manufacturers.

Not quality assurance. This is an experiment to obtain a compressive strength value to use for the design.

Nope. We can all see your bluster. When provided the calcs from Bazant, and a technical paper to review, you have avoided it like the plague.

I've pointed out the huge problems I have with his paper.

Originally posted by Azp420
reply to post by Joey Canoli

 

During progression, stuff would have fallen on the core floors a,d broken their connections. this eliminates the core column bracing. So the core columns break easily at their connections.

This is what makes stuff falling on floors important, and your above statement a laugher.

But we did not see columns sticking up in the air above the wave of destruction.

This proves your ignorance.

Google WTC spire and let me know if you changed your mind.

If you cannot, then you are insane.

Originally posted by Azp420

I can name 1226 other architects and engineers that refute it. Most probably don't frequent this site though.

Can you point me to the technical paper that has rocked the structural engineering and architectural professions to their very cores then?

It should be easy, since so many of them agree, right?

No?

They have produced nothing?

Imagine that......

Originally posted by Azp420

I'm not suggesting the collapse should have been halted either. I am merely supporting the OP video in that there should have been deceleration jolts as each floor impacted the next,

Truthers have found Tony Szamboti's jolts. They're less than what he claims they should be, so he rejects their findings.

the911forum.freeforums.org...

and that there should have been no way near free-fall acceleration.

I think there's a consensus, even fromtruthers, that it was at about 70% of FFA.

If you think this is still too fast, present your evidence, not your incredulity.

Originally posted by Azp420

I was thinking more along the lines of the 44 Story Mandarin Oriental Hotel Building in Beijing, but there are numerous examples.

If you're truly an SE, then it's an absolute disgrace that you would take this building, which:

1-was built with code recommendations that NIST proposed to survive fires
2- had zero core columns, bur rather an atrium from ground level to roof
3- was not completed, so less fire load
4- columns encased in concrete or concrete only columns ( Iforget now)

and try to compare this to the towers.

Disgraceful. You should retire immediately due to your ignorance and misrepresentation of facts.

To achieve a free-fall (or anything close to) acceleration, all the gravitational potential energy must be converted to kinetic energy and remain as kinetic energy.

And again, it was about 70% FFA.

Support your opinion with facts.

[edit on 21-7-2010 by Joey Canoli]

reply to post by Azp420


So you can name 1200+ engineers that support the idea what about the tens of thousands that DONT!

As for your comments re steel framed buildings and fires FIND another before or after 9/11 that was hit with a plane then went on fire that was also built to the same codes and construction methods!

If you google hard YOU can find steel framed buildings that have collapsed due to fire!

Originally posted by wmd_2008
reply to post by Azp420

 

So you can name 1200+ engineers that support the idea what about the tens of thousands that DONT!

And you can name the tens of thousands that DONT! [sic]?

If you can't then your argument is mute because you can not speak for those who haven't spoken.

If you google hard YOU can find steel framed buildings that have collapsed due to fire!

You can? Then post one because I have googled hard. Remember though it has to be a complete global collapse with the outer walls on top of the debris pile, as in WTC 7. Or the same but with the outer walls ejected some distance from the building, as in the towers. Partial collapse, or collapse of none load bearing areas do not count as they are to be expected. Oh, and the collapse has to be from one hours worth of fire as to represent WTC 2. Otherwise you'll have another, well you know....

reply to post by ANOK


So lets see this event happened in 2001 NOW if what you think was true do YOU really think only 1200+ would have signed up to this
THATS ALL THAT NEEDS TO BE SAID !

RE steel framed building collapse will get the link on later because I am going on site just now!

Originally posted by Azp420

3- don't know that steel columns can fail due to moderate temp creep, if the loads are high enough, at temps as low as 250C in 1 hour, and so make the ridiculous and moronic claim that steel can't fail at 250C.

It would most definitely not fail at temps as low as 250C in 1 hour,

You claimed that I was having this discussion with someone else.

Right here, you make the same claim.

You have dodged the engineering question put to you by claiming that you were not part of the discussion. This now proven to be a lie.

Now address this:

Does the 250C creep that Bazant writes about a realistic scenario or not? Replies about how no other steel building.... is not an answer that an engineer should be proud of. It is a dodge.

An objection of 250C creep to failure in 1 hour should be accompanied by engineering support, not incredulity.

Originally posted by Azp420

So gravity magically protects the top third from being crushed? Every action has an equal and opposite reaction. The strong axis of the top third fell symmetrically into the strong axis of the bottom third. At the point of impact almost equal forces (with the small difference due to self weight) would have to be survived by both thirds. You're telling me that self-weight made up a large proportion of the overall forces, I find that highly unlikely, especially as nobody can produce an experiment or computer model replicating this.

The proof that this is exactly what happens in the real world, and your misapplication of physics is proven in verinage. The top part crushes down the bottom part, with virtually zero crush up until the top reaches the ground.

You cannot dispute this fact with anything but incredulity, for you have zero facts to support it.

reply to post by Joey Canoli


Excellent find!

It's such an example of what has been said so many, many times here in these forums and threads...people couldn't see it in their minds' eyes no matter haw many times it was described in words. A few of us could, though...and watching the videos ad nauseum form 9/11, we could see it there, too.

It is most compelling (in case it hasn't been noticed yet) HOW the collapse initiation sets in...AT the point of destruction, as supports are 'removed'; or "minimized" would be a better term.

That parallels quite evidently the events of 9/11...and the subsequent over-stressing, and progression of collapses.

I was particularly interested in noticing the amount of lateral ejecta, and the forces it exhibited. Bearing in mind there were no explosives used!!

Gravity. Force. Mass. Acceleration. F = MA

The physics are undeniable.

Hollywood movie-making techniques depict fantastical simulations and seem to have colored the perceptions of many who expect real-world events to mirror the fiction on the movie screens....

Originally posted by wmd_2008
reply to post by ANOK

 

So lets see this event happened in 2001 NOW if what you think was true do YOU really think only 1200+ would have signed up to this

THATS ALL THAT NEEDS TO BE SAID !

RE steel framed building collapse will get the link on later because I am going on site just now!

LOL again just assumptions.

Most professionals are not going to risk their career by being vocal about something as sensitive as 9-11.

Silence does not equate to support of the OS. 1200 is quit a lot imo. Maybe you didn't notice but most of us are anonymous posters, how do you know I'm not one of the tens if thousands you claim support the OS because we haven't put our real name out there?

Yes get that link please.

reply to post by weedwhacker


Again the evidence you all keep ignoring...





The tops did not do what the top did in that verinage demolition.

You are the ones failing to understand the physics. That verinage demolition uses hydraulics to push columns out of place, the bottom section is pre-weakened. The falling top section was 50% of it's height and it was a concrete, not steel, building.
The top was set up to hit the bottom squarely, this did not happen with the towers. WTC 2 top was tilting under angular momentum, a completely different set of physics taking place.

Again you guys are just showing your lack of understanding of simple physics in your desperation to shut people up.