Video Nullfies Pancake/CD Theory

How is consensus a valid argument for a physics problem?

I can only make one conclusion as to that line of thinking. PLB, you only care that people believe the OS, regardless of whether it's true or not. You're not here for a discussion.

Well silly me, there I go pointing out the obvious again.

By your logic you're on the wrong side...

- 28% of voters believe Saddam Hussein was involved in the 9/11 attacks. 36% of Romney voters believe Saddam Hussein was involved in 9/11, 41% do not.

www.abovetopsecret.com...



www.abovetopsecret.com...

www.abovetopsecret.com...

reply to post by ANOK


ANOK, every single time you comment you make a fool out of yourself. How many times do you have to comment without understanding before you are embarassed into actually learning?

I read some of your past posts to understand what might have motivated this. It seems you used to be a jet engineer and after that you made graphical skins for a plane simulation game.

Is this it? You think that a bit of materials science and being taught what torsion and tension is is sufficient?

You couldn't understand a simple two axis graph that was presented to you.

I've never seen you draw a free body diagram at all.

Why do you persist in this? Do you really believe that you are an expert? Do you really believe that SE certifications are only for show?

Just go off and learn, take a course, or embarrass yourself in a debate with me and be shamed into it. I don't really care which, just sick of seeing the same arrogant posts with no backing understanding.

reply to post by exponent

No way out of the conundrum with physics, logic, reason and math magic? Newton, Euler, Galileo and Archimedes disagree with you? Do not worry, Arthur Schopenhauer knows what to do: argumentum ad personam!

The tricks, dodges, and chicanery, to which they [men] resort in order to be right in the end, are so numerous and manifold and yet recur so regularly that some years ago I made them the subject of my own reflection and directed my attention to their purely formal element after I had perceived that, however varied the subjects of discussion and the persons taking part therein, the same identical tricks and dodges always come back and were very easy to recognize. This led me at the time to the idea of clearly separating the merely formal part of these tricks and dodges from the material and of displaying it, so to speak, as a neat anatomical specimen.

Originally posted by Akareyon
Yes, because it is not my proposal and has been in place for a long time. That is why full floor failure occurs rarely, except in controlled demolitions and alien attacks, and seldomly global progressive collapse ensues. Because structural systems are built with a FoS and with enough redundance so this sort of thing can not happen except if someone helps it along.

I propose that maybe we can better make buildings so that full floor failure can not occur. You insist that buildings should be designed such that if full floor failure occurs, collapse is arrested, else nobody will think the building is safe to enter. But now you basically agree that indeed full floor failure is an extremely rare event. It looks like we are starting to get more and more in agreement.

4.2.4.1 Structural integrity is the ability of the structural system to absorb and contain local damage or failure without developing into a progressive collapse that involves the entire structure or a disproportionatelylarge part of it. [...] Compartmentation (subdivision of buildings/stories in a building) is an effective means of achieving resistance to progressive collapse as well as preventing fire spread, as a cellular arrangement of structural components that are well tied together provides stability and integrity to the structural system as well as insulation.

It is essential that the engineer of record take all necessary precautions to ascertain that the structure does not fail catastrophically during testing. A careful assessment of structural conditions before testing is a fundamental requirement.

To summarize: unintentional full floor failure almost never happens in reality. Neither of your sources show it happening either.

See? Yet it happened in the Twins and led to global progressive collapse from top to bottom.

Rule of mine? I'll try to get the 1963 version of this (it might cost a penny or two) just to prove you wrong on this one as well.

I already challenged you to show any source that shows a similar definition of FoS as yours. So by all means, prove me wrong, and I will gladly accept that you are right, and fully agree something fishy was going on in the WTC design.

Fine, then open the document I linked to and scroll down to page 68 of the PDF, start reading at C2 - Calculation of required strength, until you reach the definition of P_e1 (which you need for the formula that calculates B_1 which in turn determines the required flexural and axial strength in members of lateral load resisting systems M_r in second order analysis procedures) which is defined as (π²*E*I)/(K_2*L)² , where E = modulus of elasticity of steel = 29,000 ksi (200 000 MPa), I = moment of inertia in the plane of bending in m^4, L = story height in mm and K_2 = effective length factor in the plane of bending, calculated based on a sidesway buckling analysis. Since that formula has been known since Euler, I'm pretty sure it was in the 1963 version of the Specification for Structural Steel Buildings by the American Institute of Steel Construction too. Oh, wait, what does it say here:

The effective length method for assessing member axial compressive strength [...] has been used in various forms in the AISC Specification since 1961.

You may also want to read Appendix 6 - Stability Bracing for Columns and Beams. I challenge you to show that this is only in there because of the Twins and wasn't, in one form or another, in the 1963 edition.

If you need a video tutorial how to fold tin foil hats, let me know.

You did a nice googling effort, but nothing of this is about FoS being Fc/mg, nor does it anywhere state that Fc must be greater that mg. In fact, the section you are looking at are about static load strength of the structure.

There was (expert!) consensus once that earth is the middle of the universe and everything revolves around it, that the indigenous people of America have no right to dwell upon the soil they inhabited for centuries, that people with darker skin are animals in human shape and fit for slavery, that Jews are guilty for the misery of the aryan race and deserve to be murdered on an industrial scale.

So let me guess, you used your telescope and based on your observation created your own model of our earth in the universe, and came to the conclusion that that the earth revolves around the sun revolved around the galaxy etc?

And after that you discovered DNA, mapped the human genome, and came to the conclusion that hey, we are all pretty much equal.

Or do you rely on experts for all that to know? (that is of course a rhetorical question).

reply to post by ANOK


ANOK, does that FoS also cover 15+ dynamic floors impacting vertically as well? I'd LOVE to see this.

Originally posted by -PLB-
I propose that maybe we can better make buildings so that full floor failure can not occur. You insist that buildings should be designed such that if full floor failure occurs, collapse is arrested, else nobody will think the building is safe to enter. But now you basically agree that indeed full floor failure is an extremely rare event. It looks like we are starting to get more and more in agreement.

Yes indeed -- because if even full floor failure is so unlikely to occur, global progressive collapse resulting from single floor failure will not happen at all :-)

You did a nice googling effort, but nothing of this is about FoS being Fc/mg, nor does it anywhere state that Fc must be greater that mg. In fact, the section you are looking at are about static load strength of the structure.

In fact, the section we are looking at employs exactly the same formula ( F_c=(π²*E*I)/(K*L)² , which I posted earlier, after which you challenged me to show you any source that shows a similar definition of FoS as mine) to compute the minimum required strength of each steel frame member, and since FoS=strength/load... ;-)

And the other way round, like FoS=F_0/m*g? You surely you don't want to rely on F_0, the peak of the load displacement curve or ultimate strength, for your FoS calculations for quite a simple reason: once you're there, you're past the yield strength, and you have left the elastic region. You're way into the irreversible plastic phase of buckling already.

May I remind you of your own words?

So by all means, prove me wrong, and I will [...] fully agree something fishy was going on in the WTC design.

Back to our little sophistry...

So let me guess, you used your telescope and based on your observation created your own model of our earth in the universe, and came to the conclusion that that the earth revolves around the sun revolved around the galaxy etc?

Errrrm, nope. I can think both ways, you know. Me as the center of the universe in the middle of a vast and breathtaking landscape and everything - the moon, the stars and the planets and the sun - revolving around me in beautiful epicycles. And me in the outer rim territories far away from the brilliant center of one galaxy among thousands of thousands, speeding around an unimportant star on a speck of dust. It's just a matter of perspective, you see, and in reality it doesn't make much of a practical difference either.

Seriously though, I watched one venus transit, one solar eclipse and two lunar eclipses. The predictions of the "experts" were verifiable for me, so I have no reason to doubt that their models for the solar system have a high degree of reliability and accuracy and as long as it works that fine, I will not object.

And after that you discovered DNA, mapped the human genome, and came to the conclusion that hey, we are all pretty much equal.

I came to that conclusion long before I read about the human genome project for the first time (must have been in the 90ies or so).

Others came to that conclusion long before the discovery of the DNA. Back then, they were dissenters, I guess. According to you, they were wrong, because they were way ahead of the consensus. Today, they would be right. Tomorrow, a new consensus may have formed because some expert proves that gingers exhibit traits that cannot be regarded human or of terrestrial origin.

I still don't see what you're trying to say. That I needed an expert to tell me it's not so cool to judge my Sri Lankan and Turkish first class mates by the color of their skin?

Or are you trying to insinuate that I'm denying the importance of people dedicating their lives to a cause and becoming good and knowledgeable at it?

Then you did not get my point. Dendrochronologists enjoy my deepest respect, for example. What I was trying to say is that my brain doesn't automatically stop working just because some expert proclaims his brand new theory; and that consent is no criterion for truth in matters of science.

Originally posted by Akareyon
In fact, the section we are looking at employs exactly the same formula ( F_c=(π²*E*I)/(K*L)² .

Sigh... this is the formula to calculate maximum or critical force before a column buckles. Aka F0 in Bazants paper. It is not the integral of F(u), aka Fc.

I have no idea where you got this idea. I will just cite Wikipedia for you:

In 1757, mathematician Leonhard Euler derived a formula that gives the maximum axial load that a long, slender, ideal column can carry without buckling. An ideal column is one that is perfectly straight, homogeneous, and free from initial stress. The maximum load, sometimes called the critical load, causes the column to be in a state of unstable equilibrium; that is, the introduction of the slightest lateral force will cause the column to fail by buckling. The formula derived by Euler for columns with no consideration for lateral forces is given below. However, if lateral forces are taken into consideration the value of critical load remains approximately the same.

Thats the description introducing that very formula you come with.

I still don't see what you're trying to say. That I needed an expert to tell me it's not so cool to judge my Sri Lankan and Turkish first class mates by the color of their skin?

My point is that nearly everything about science you know comes from consensus among experts. As layman, the sane position is to follow the expert consensus. As expert, it is your duty to punch holes in the consensus.

As an example, I am 100% positive that you did not derive that formula for critical force yourself. You rely on expert consensus that it is correct. If you had derived it yourself you would have understood that it is F0 in Bazants paper, and not Fc.

Originally posted by -PLB-
My point is that nearly everything about science you know comes from consensus among experts. As layman, the sane position is to follow the expert consensus. As expert, it is your duty to punch holes in the consensus.

But there is no consensus among experts about 911. That's just your illusion.

All you have is the NIST report and nonsense from Bazant.

There is absolutely NO consensus that sagging trusses can pull columns in.

All you are doing is trying claim that this is all above our intelligence, and only your "experts" can understand it.
Because that's all you can do, if you had proof you wouldn't need to do that.

Still waiting for proof that sagging trusses can pull in columns. I haven't seen anything since your last failure with that PDF you claimed explains it...

www.abovetopsecret.com...

Not much point in experts if you don't understand what they're saying.

Originally posted by GenRadek
reply to post by ANOK

 

ANOK, does that FoS also cover 15+ dynamic floors impacting vertically as well? I'd LOVE to see this.

Of course it does. Every component has to conform to the FoS.

But regardless your claim that 15 floors impacted a single floor, and cause them to collapse, is nonsense. You only have to watch the video's to see that. Clearly you can see the top floors are blowing out before the bottom floors start blowing out, so obviously not what you claim.



We have discussed this 15 floors crushing 95 floors to the foundations many times. If you stop ignoring the laws of motion, equal opposite reaction, and momentum conservation, you would know that 15 floors can not crush 95 floors. For each floor impacted you lose Ke to break connections etc. Not too mention the dropping floors would also be crushed, not just the impacted floors. The collapse would slow and arrest. So there had to be another energy acting on the towers that was not investigated.

Originally posted by ANOK
All you are doing is trying claim that this is all above our intelligence, and only your "experts" can understand it.

Not at all. There are very few people I know of that fail to understand it. I don't know anyone with an above average education (bachelor or similar) that does not understand it.

reply to post by -PLB-


Understand what PLB, what you can't even show can happen?

No comment on the fact that you can see the top floors blowing out ahead of lower floors collapsing?

Why did you choose to comment on what you did, and completely ignore that?

Do you just feel an overwhelming urge to say something regardless of whether it has any point to the discussion or not?

So how do sagging trusses pull in columns now that your catenary action idea failed miserably?

I'll just keep reminding you of this PLB...

www.abovetopsecret.com...

So do you have anything else? Obviously not.

Originally posted by ANOK

Originally posted by GenRadek
reply to post by ANOK

 

ANOK, does that FoS also cover 15+ dynamic floors impacting vertically as well? I'd LOVE to see this.

Of course it does. Every component has to conform to the FoS.

Really? WOW! I'd love to see the documentation of this amazing ability!

But regardless your claim that 15 floors impacted a single floor, and cause them to collapse, is nonsense. You only have to watch the video's to see that. Clearly you can see the top floors are blowing out before the bottom floors start blowing out, so obviously not what you claim.

ANOK, what is blowing out? Oh yes, the pulverized drywall and sheetrock that is getting crushed by the collapsing floors. That would be the floors collapsing on top of the floors below the top segment. Your own clip is showing the top section coming down as one unit. This is hilarious ANOK shot yourself in the foot. Hoisted by your own petard!


We have discussed this 15 floors crushing 95 floors to the foundations many times. If you stop ignoring the laws of motion, equal opposite reaction, and momentum conservation, you would know that 15 floors can not crush 95 floors. For each floor impacted you lose Ke to break connections etc. Not too mention the dropping floors would also be crushed, not just the impacted floors. The collapse would slow and arrest. So there had to be another energy acting on the towers that was not investigated.



Oh blah blah blah, ANOK, just throwing out random physics buzzwords means diddly squat if you have no clue what they mean or how to utilize them properly. If a physics teacher read your responses, I'm positive hed have a laughing fit right before dropping a big ol "F" on this wreck. Once again you ignore any counter evidence that destroys your flawed version of events. Plus it was not 15 vs 95, but it was 15 vs 1, 16 vs 1, 17 vs 1, etc, all the way down.

Originally posted by -PLB-
this is the formula to calculate maximum or critical force before a column buckles. Aka F0 in Bazants paper. It is not the integral of F(u), aka Fc.

emphasis mine

In 1757, mathematician Leonhard Euler derived a formula that gives the maximum axial load that a long, slender, ideal column can carry without buckling.

emphasis mine

You are right that F_critical is not the mean crushing force F_c. F_critical is the force you can apply to a long, slender, ideal column before it leaves the linear portion of the load-displacement curve, just before it goes plastic. When it goes plastic, it is deformed. At F_0, it has left the linear portion of the load-displacement curve and is deformed already and will not get back to its original state. It is too late already. So you want to know how long the column stays in the linear portion of the load-displacement curve where it remains elastic and in a stable equilibrium. That's what the Euler equation is for. And then you double that and have an FoS of 2. Automatically, F_c will be above m*g.

I will assume for the sake of the discussion that you are totally right in saying that F_0=F_critical. In that case, the engineers did not use the energy method to find out that m*g is above the maxwell line and progressive collapse would occur as soon as the threshold - the small area between F(u) and m*g to the left of u_c - is exceeded. Because that's what you would want to do if you were using extremely brittle material. F_0 would be extremely high, and the peak of the F(u) curve extremely narrow and the slope behind F_0 extremely steep so you would keep u - the length of each member and therefor the area below m*g and above F(u) - so small that the stuff above doesn't pick up enough kinetic energy to crush the next floor. It is highly unlikely all this was not known until today. It's like saying "wow, who would have thought that wheels must be circular in shape!"

So the discussion comes full circle again. You are saying the towers were erected in an unstable equilibrium. You find nothing wrong with that, although you acknowledge that no other structure - except your own dishwasher tablet tower - ever exhibited that phenomenon. And you can not explain how the towers could withstand lateral forces - such as hurricanes - before that, when these lateral forces were transmitted via moment to the core columns and could easily have crushed one or more columns near the base, resulting in the toppling of the whole tower.

My point is that nearly everything about science you know comes from consensus among experts. As layman, the sane position is to follow the expert consensus. As expert, it is your duty to punch holes in the consensus.

Do you realize what you are saying?

You're essantially telling me to shut up because I have no clue. You endorse intellectual aristocracy and expert dictatorship. You ring the death bell for democracy and the voice of the people. You undo the age of enlightenment and return to the dark ages where "truth" was preached from the pulpit in Latin so the peasant does not understand and must rely on hearsay and superstition. You make science a religion where truth is veiled behind curtains of complicated formulae and technical terms.

I dissent.

As an example, I am 100% positive that you did not derive that formula for critical force yourself.

I know how to derive it. I know also by heart how to derive pi and how to prove that sqrt(2) is not a rational number, even if I haven't found out myself how to derive it. Yet I understand the process. I do not rely on experts to tell me pi is 3.14159...something. It could be something else. I checked when I was sixteen or seventeen. It isn't. I also checked if a vertical structure can collapse progressively from top to bottom. It can. If the effective FoS < 1.

You rely on expert consensus that it is correct.

No, on experience and sound reason.

If you had derived it yourself you would have understood that it is F0 in Bazants paper, and not Fc.

You are right. I accept your intellectual superiority.

Originally posted by GenRadek

So the whole top section getting smaller in height, while the lower floors do nothing, is Sheetrock blowing out?

Every excuse in the book.

Originally posted by Akareyon
And then you double that and have an FoS of 2.

I must correct myself. You don't double the strength, you double the load it can support to get an FoS of 2.

Isn't this thread getting old?
The same few people go back and forth. No one is changing their mind.

What's the point?
Until the non experts graduate engineering school this whole thing is just a bar room argument without floozies to take home.

Originally posted by samkent
Isn't this thread getting old?
The same few people go back and forth. No one is changing their mind.

What's the point?
Until the non experts graduate engineering school this whole thing is just a bar room argument without floozies to take home.

Plb is close. And this is one of the most interesting 9/11 threads ever.

Maybe you should try reading it and following along.

Originally posted by Akareyon
And then you double that and have an FoS of 2. Automatically, F_c will be above m*g.

Nope, Fc will not automatically be above mg. The figure we have been discussing clearly shows this. How did you come to this conclusion?

In that case, the engineers did not use the energy method to find out that m*g is above the maxwell line and progressive collapse would occur as soon as the threshold - the small area between F(u) and m*g to the left of u_c - is exceeded.

In the energy method you also do not calculate Fc. You can't use it to determine if mg is below Fc.

Because that's what you would want to do if you were using extremely brittle material. F_0 would be extremely high, and the peak of the F(u) curve extremely narrow and the slope behind F_0 extremely steep so you would keep u - the length of each member and therefor the area below m*g and above F(u) - so small that the stuff above doesn't pick up enough kinetic energy to crush the next floor. It is highly unlikely all this was not known until today. It's like saying "wow, who would have thought that wheels must be circular in shape!"

You don't make any sense here. If you have a very short but high peak, the area below m*g and above F(u) will be very large. In fact, the narrower the peak, the larger the area.

So the discussion comes full circle again. You are saying the towers were erected in an unstable equilibrium.

Nope, I am not. It is in a meta stable state. We discussed this before didn't we?

You find nothing wrong with that, although you acknowledge that no other structure - except your own dishwasher tablet tower - ever exhibited that phenomenon.

I don't acknowledge that. In fact, I say that all buildings are in a mete stable state.

And you can not explain how the towers could withstand lateral forces - such as hurricanes - before that, when these lateral forces were transmitted via moment to the core columns and could easily have crushed one or more columns near the base, resulting in the toppling of the whole tower.

???? Its in the NIST report. Read it.

In the meanwhile, you still haven't shown any literature that says FoS=Fc/mg, or that building codes state that Fc must be larger than mg. All you have done is show that indeed, FoS=F0/mg.

I dissent.

Dissent all you like, I am not stopping you. This forum is filled with people who reject mainstream science and make up their own physics. Without exception its all rubbish.

No, on experience and sound reason.

I don't believe you at all. If the formula had said Fcritical=(2piEI)/(KL)^2 you would have copied it without question and said the exact same thing. Except you would have been about a factor 2 wrong. But because you trust the scientific consensus, you trust the formula you copied is correct.

And it would be foolish to not trust it, which is my point. This post also shows you rely on experts.
You didn't figure this our yourself, you found it while you were Googling.

Originally posted by -PLB-
Nope, Fc will not automatically be above mg. The figure we have been discussing clearly shows this. How did you come to this conclusion?

Wait...

You don't make any sense here. If you have a very short but high peak, the area below m*g and above F(u) will be very large. In fact, the narrower the peak, the larger the area.

And the smaller the effective length - something you do using braces, in case you forgot I made that point already - the smaller that area. Of course it seems I don't make any sense if you misinterpret me on purpose. Or think of the core frame as of a few slender 400 meter columns without any horizontal or diagonal beams and bracings.

So the discussion comes full circle again. You are saying the towers were erected in an unstable equilibrium.

Nope, I am not. It is in a meta stable state. We discussed this before didn't we?

Did you - or was it exponent - not reply on that occasion, after I have called such a tower a metastable system, that all buildings are in a meta stable state and the only way to stabilize them would be to put all members flat on the ground? Did I not agree? Your argument is invalid.

If you insist that the potential energy of 981 GJ was converted to kinetic energy by the energy input of 2.1 GJ, a deviation of roughly 0.2% from the default state of the system triggered a global system collapse and much less even would have sufficed. So indeed you are saying that the the towers were erected in an unstable equilibrium. You are just using much more words for that.

You find nothing wrong with that, although you acknowledge that no other structure - except your own dishwasher tablet tower - ever exhibited that phenomenon.

I don't acknowledge that. In fact, I say that all buildings are in a mete stable state.

You say all buildings are in an unstable equilibrium.

And you can not explain how the towers could withstand lateral forces - such as hurricanes - before that, when these lateral forces were transmitted via moment to the core columns and could easily have crushed one or more columns near the base, resulting in the toppling of the whole tower.

???? Its in the NIST report. Read it.

Been there, done that. Do want to know how many words exactly they used to describe the collapse sequence in the "Final Report on the Collapse of the World Trade Center Towers" with the objective No. 1 "Determine why and how WTC 1 and WTC 2 collapsed following the initial impacts of the aircraft" (p. xxix)? And would you like to compare it to the computing power for the FEM of each turbine blade of the aircraft? Just so you get some sort of perspective.

In the meanwhile, you still haven't shown any literature that says FoS=Fc/mg, or that building codes state that Fc must be larger than mg.

I haven't, that is true, and I have corrected myself. Read and understand the AISC document I linked, at least the parts I mentioned. It's all about making a steel frame sound and safe with bracings and connections and calculating momenta and using structural analysis. With all that in place, it is impossible to build a steel frame that progressively telescopes into the basement with hardly any friction forces decelerating the descent.

This forum is filled with people who reject mainstream science and make up their own physics. Without exception its all rubbish.

Welcome to the club then :-)

I don't believe you at all. If the formula had said Fcritical=(2piEI)/(KL)^2 you would have copied it without question and said the exact same thing. Except you would have been a factor 2 wrong. But because you trust the scientific consensus, you trust the formula you copied is correct.

And it would be foolish to not trust it, which is my point. This post also shows you rely on experts.
You didn't figure this our yourself, you found it while you were Googling.

You won't believe or understand this because you prefer blind trust over scrutinizing what you learn, but I'll tell you anyway: when I tried to verify the formula and my allegations and studied yield strengths and stress-strain curves , something bugged me quite a lot so I tried to find a solution. I found it. And shared it or everyone who follows this discussion trying to make up his mind and looking for the truth and good arguments pro and con. And I freely and honestly admitted a mistake so others don't carry it elsewhere. That makes me a better scientist than you, who with every mistake I make rejoices and pretends I couldn't tell the difference between a cow pat and a pizza.

Right now, by the way, I'm reading a 1966 paper on our little subject... hold your breath, dear friend, quotes are coming :-)

reply to post by ANOK


Gee ANOK, did you notice something about the collapse from up close video?


The columns bent inward. As they bent inward and started to collapse, the top section telescoped inside and behind the lower section. You really believe the top segment just turned into dust? Really? And all the floors of the top segment just vanished into nothing? You might want to reconsider that image you put up.......... Mass does not vanish. Neither do steel columns, steel trusses, steel decking, and concrete. How can you believe something like that? I'm sure your physics teacher would have a heart attack if he heard you spewing such ignorance.

But I am waiting for you to explain just how the trusses, floors, decking, pans, etc were ejected and where can I find evidence of this occurring. Any thing will do. Geeze ANOK, I could have sworn I asked you this before, many many many many times. And you have yet to answer it. But you insist you are right but cannot even back it up. Well, now is your chance at redemption!