Professional engineer Jon Cole cuts steel columns with thermate, debunks Nat Geo & unexpectedly repr

reply to post by bsbray11


Make me laugh and come with an answer. It will be fun how to see what you will do with the voltage, just take 1vpp.

Just for fun (as electrical engineer you must find it fun to solve (real) problems) and to put you out of misery:

The differential equation of your setup is:

Rq'(t) + C^-1q(t)=Am*sin(at)
a Laplace transform to ease things a bit.

Q(s)=X(s)/Y(s).

X(s) = L[Am*sin(at)] = Am/(s^2-a^2)
Y(s) = Rs + 1/C = (R(s + 1/RC))

So Q(s) = Am / (R(s + 1/RC))(s^2-a^2)

Well, not easy. Lets try partial fraction expansion:

A/(R(s + 1/RC)) + (Bs + D)/(s^2-a^2) = 1 / (R(s + 1/RC))(s^2-a^2)

A(s^2-a^2) + Bs(R(s + 1/RC)) + D(R(s + 1/RC)) = 1

s^2(A + BR) + s(B/RC + DR) + A*a^2 + D/C = 1
D=-B/RC
A=-B
-Ba^2 - B/R^2C^2=1
B=1/(-a^2 - 1/R^2C^2)
A=1/(a^2 + 1/R^2C^2)
D=1/(a^2RC+1/RC)

So we get a grand total of:

Q(s) = Am/R( (1/(a^2 + 1/R^2C^2))/(R(s + 1/RC)) + (s/(-a^2 - 1/R^2C^2))/(s^2-a^2) + (1/(a^2RC+1/RC))/(s^2-a^2)

Then all there is left is reverse transform. We recognize a power e, a cosine and a sine. This results in:

q(t) = Am/R(a^2 + 1/(R^2C^2)) e^-t/RC - Am/R(a^2 + 1/R^2C^2) cos(at) + Am/R(a^2RC+1/RC) sin(at)

So there we have the equation of the charge.

Now we want to know the position the charge is maximal (that is the only sensible thing your question can be). So we need to take the derivative of q(t) and equate it to 0:

de^-t/RC/dt = (e^-t/RC)/RC
dcos(at)/dt = acos(at)
dsin(at)/dt = -asin(at)

So we get:

q'(t) = Am/R(a^2 + 1/(R^2C^2)) *(e^-t/RC)/RC - Am/R(a^2 + 1/R^2C^2) *acos(at) + Am/R(a^2RC+1/RC) *-asin(at) = 0

Now all that is left is find t for which this is true. But I will leave that to you.

It took me over an hour to solve this. There may be some errors in it as I didn't double check it (edit: I did spot an error, lets see if you can find it too). Anyway, I will get a "you took that from google" now. So it wasn't useful for this thread, but its always good to refresh your skill.

Edit: The quick way: because your RC time is very large compared to T, the moment that q is maximal is very close to T/2. But like I said, thats a cheap cop out.

Originally posted by bsbray11
I could get an answer in seconds

Seconds become minutes. Minutes become hours. Hours become days.

Prediction: there will never be an answer.

I think you don't have a clue how to solve the problem you came with yourself (well, your question didn't make sense anyhow which exposes your lack of insight). You bluffed and got called. I don't even think you can spot the (some obvious) errors I made, its all gibberish to you.

I got linked to this thread by a friend and I must say I was engrossed by bsbray's increasing arrogance. It's been a while since I posted, but now he's beginning to believe he has authority to speak over engineering matters.

It's quite simple bsbray, the cardington tests do not prove what you want them to prove. They didn't when you attempted to use them for limiting temperatures, they didn't when you attempted to use them for limiting sag, and they still don't prove what you want when you are trying to use them to limit deflection.

For a start, the test you're using are beam floored, over a very small span. As you (should) know, thermal expansion is a volumetric effect, and so in the direction of motion the length of the span is of high importance in determining the force applied.

As the span was so large, and the flooring was truss and therefore made of smaller elements in opposition, the sagging would have been much larger and quicker than at Cardington.

You also seem to be ignoring the floor restraints provided and the large difference once again with the Cardington tests.

In short, you've convinced yourself that all your evidence points to one conclusion, and then even when you post the evidence that doesn't support you, you are too blind and to confident to see it.

Nothing has changed since last I posted here, other than you now have an even more implausible mechanism that there is still no evidence for.


All credit to Jon Cole though, he created a mechanism I didn't think was physically plausible, and even though it doesn't help the conspiracy theory much he did a good job of putting theory into practise and coming up with a workable steel cutting method with thermite.

reply to post by exponent


Gotta love how you support Government views worldwide..
What a patriot you are..

Originally posted by backinblack
reply to post by exponent

 

Gotta love how you support Government views worldwide..
What a patriot you are..

What are you talking about. Cardington was a test conducted in part by my local university.

I'm not a patriot, I voted Liberal Democrat in the last election and I am not an American.

Stop your attempted slander or I will report it.

Originally posted by exponent
I got linked to this thread by a friend and I must say I was engrossed by bsbray's increasing arrogance. It's been a while since I posted, but now he's beginning to believe he has authority to speak over engineering matters.

You mean, like any other capable person, I have the ability to point out scientific studies and other facts. And that's different from anyone else posting here, such as yourself, how?

It's quite simple bsbray, the cardington tests do not prove what you want them to prove.

I already posted the conclusions from the Cardington tests themselves. It's hard to make up what the scientists who actually performed the study said about it.

For a start, the test you're using are beam floored, over a very small span. As you (should) know, thermal expansion is a volumetric effect, and so in the direction of motion the length of the span is of high importance in determining the force applied.

You're only leading up to shooting yourself in the foot if you're about to argue that the expansion forces should have been even greater in the WTC Towers.

As the span was so large, and the flooring was truss and therefore made of smaller elements in opposition, the sagging would have been much larger and quicker than at Cardington.

Exactly... so the expansion force would have been greater.

Someone screwed with PLB when he was a kid, so he doesn't know that larger forces produce larger deflections than smaller forces. Are you also going to ignore the fact that his own sources showed that the expansion forces are greater than any "pull" force such as what NIST claimed was responsible for the deflection? Where is the photographic evidence of widespread deflection from expansion?

You also seem to be ignoring the floor restraints provided and the large difference once again with the Cardington tests.

It was only important that the beams were firmly restrained on both ends for the sagging to take place in the middle. This would have been the case at the WTC too. Now I guess you are going to ignorantly argue that sagging at the WTC couldn't have even taken place because the trusses were unrestrained on one end. How is that going to help your argument?

All credit to Jon Cole though, he created a mechanism I didn't think was physically plausible

I'm surprised you're able to actually admit that.

Everyone else seemed to start denying ever claiming that thermite/thermate couldn't make horizontal or vertical cuts, once that video came out.

Originally posted by -PLB-

Originally posted by bsbray11
I could get an answer in seconds

Seconds become minutes. Minutes become hours. Hours become days.

That's exactly right. I gave you the problem. So many minutes later, you figured out how to add two capacitors in parallel. Then a couple hours later, you come back and spill a bunch of overly-complicated garbage in some hilarious attempt at I-don't-know-what, and still can't do it.

I made the problem and gave it to you. You were supposed to solve it, not me.


I could have given you a simple vector addition problem and you would have spent hours trying to Google how to work those too, probably also in vain.

You were lying about your education, and arguing from any alleged education is a fallacy in the first place. You demonstrated one misunderstanding of basic physics after another and so I have no use trying to have a discussion about physics with you. It's completely pointless because you have no clue what you're talking about and are arguing from some religious faith. I really am done. Now whine about it all you want to.

Originally posted by bsbray11
You mean, like any other capable person, I have the ability to point out scientific studies and other facts. And that's different from anyone else posting here, such as yourself, how?

The difference is that when they disagree with you they lose credibility in your eyes.

I already posted the conclusions from the Cardington tests themselves. It's hard to make up what the scientists who actually performed the study said about it.

Indeed it is, but once you ignore enough information, you can start to form a weak chain with the remaining tenuous facts.

You're only leading up to shooting yourself in the foot if you're about to argue that the expansion forces should have been even greater in the WTC Towers.
...
Exactly... so the expansion force would have been greater.

Agreed.

Someone screwed with PLB when he was a kid, so he doesn't know that larger forces produce larger deflections than smaller forces. Are you also going to ignore the fact that his own sources showed that the expansion forces are greater than any "pull" force such as what NIST claimed was responsible for the deflection? Where is the photographic evidence of widespread deflection from expansion?

Different system, truss floors have a bottom chord in tension, and although a beam has a similar thing it is not a unique element. Plus of course the difference in construction and loading. It wouldn't be fair to make a direct comparison, only as a general concept.

It was only important that the beams were firmly restrained on both ends for the sagging to take place in the middle. This would have been the case at the WTC too. Now I guess you are going to ignorantly argue that sagging at the WTC couldn't have even taken place because the trusses were unrestrained on one end. How is that going to help your argument?

I'm not, but you have mentioned the dampers installed but without discussing the actual truss connectivity. It may be worth comparing how a truss connected to a typical column with how the beam connects in PLBs example (they're actually called different things too)

I'm surprised you're able to actually admit that.

I'm after truth, not dogma.

So, as you've been courteous to answer my questions, and I have been courteous to answer yours, here is my most important question:

Have you come up with a plausible mechanism to cause perimeter pull-in?

Thanks in advance.

Originally posted by exponent

Originally posted by bsbray11
You mean, like any other capable person, I have the ability to point out scientific studies and other facts. And that's different from anyone else posting here, such as yourself, how?

The difference is that when they disagree with you they lose credibility in your eyes.

No, when you make a logical fallacy, you lose a lot of credibility in my eyes, because for all the talk you guys do you don't actually know the significance of what you're even saying.

I already posted the conclusions from the Cardington tests themselves. It's hard to make up what the scientists who actually performed the study said about it.

Indeed it is, but once you ignore enough information, you can start to form a weak chain with the remaining tenuous facts.

Well I'll still be here when you're reading to point out what information either I or the scientists involved with that study were ignoring, when they formed their conclusion and wrote it all out, like I just posted on the other page.

You're only leading up to shooting yourself in the foot if you're about to argue that the expansion forces should have been even greater in the WTC Towers.
...
Exactly... so the expansion force would have been greater.

Agreed.

You realize this is the exact opposite direction of the force NIST hypothesized to initiate "collapse," right?

Someone screwed with PLB when he was a kid, so he doesn't know that larger forces produce larger deflections than smaller forces. Are you also going to ignore the fact that his own sources showed that the expansion forces are greater than any "pull" force such as what NIST claimed was responsible for the deflection? Where is the photographic evidence of widespread deflection from expansion?

Different system, truss floors have a bottom chord in tension, and although a beam has a similar thing it is not a unique element. Plus of course the difference in construction and loading. It wouldn't be fair to make a direct comparison, only as a general concept.

For all these differences you still can't tell me how it would mean a smaller force can cause more displacement than an even larger force. The differences are noted, and they're also apparently inconsequential to the point here, which is that the expansion forces are significantly larger than any "pull" force, and at even lower temperatures.

It was only important that the beams were firmly restrained on both ends for the sagging to take place in the middle. This would have been the case at the WTC too. Now I guess you are going to ignorantly argue that sagging at the WTC couldn't have even taken place because the trusses were unrestrained on one end. How is that going to help your argument?

I'm not, but you have mentioned the dampers installed but without discussing the actual truss connectivity. It may be worth comparing how a truss connected to a typical column with how the beam connects in PLBs example (they're actually called different things too)

If you think it's worth considering, I'll leave it to you to figure out how this could possibly make the "pull" force larger than the expansion forces.

So, as you've been courteous to answer my questions, and I have been courteous to answer yours, here is my most important question:

Have you come up with a plausible mechanism to cause perimeter pull-in?

No. And I haven't seen any evidence of columns being "pulled in" on a large scale either.

I suppose your next question will be, "Then why can't you just accept NIST's theory?"

Because it doesn't make sense, and there is no evidence to support it.

If I wanted that, and if the American people wanted that, why in the hell did we even bother investigating anything anyway?

Originally posted by bsbray11
overly-complicated garbage

That is how real engineers solve problems, its no surprise you can't even grasp the surface of it with your Mickey Mouse engineering skills. And as expected, no answer to you own question, you are clueless. Your slander has become even more pathetic now.

Originally posted by -PLB-

Originally posted by bsbray11
overly-complicated garbage

That is how real engineers solve problems

You weren't even able to solve the problem, even after trying your completely convoluted method.

Stop slinging insults dude. You were called out by 2 different people, posing multiple questions to you. You can't solve physics problems. Vectors, Newton's 3rd law, even circuits problems. You think smaller forces cause larger displacements than larger ones. It's over. Find someone else to bug. Is that so much to ask?

reply to post by bsbray11


It is interesting to see how you react when you are confronted with reality. You just repeat your slander, even when confronted with direct proof of the opposite. Like I predicted, it makes totally no difference whether I answer your question, your position doesn't change. You use your ignorance as a shield, as long as you don't understand it you can call it garbage. It is your choice, but realize you are at the wrong forum. Deny ignorance.

Originally posted by bsbray11
Well I'll still be here when you're reading to point out what information either I or the scientists involved with that study were ignoring, when they formed their conclusion and wrote it all out, like I just posted on the other page.

Could you please link me to that? I had a look through your posts in this thread but there are 15 pages of them and I couldn't see it specifically.

You realize this is the exact opposite direction of the force NIST hypothesized to initiate "collapse," right?

Yes? I don't see why you think that is a problem, NIST also did not as it is included in NCSTAR 1-6C

For all these differences you still can't tell me how it would mean a smaller force can cause more displacement than an even larger force. The differences are noted, and they're also apparently inconsequential to the point here, which is that the expansion forces are significantly larger than any "pull" force, and at even lower temperatures.

These forces are determined by different things, expansion is determined by temperature, wheras pull in is also determined by the floor loading. How can you say that the expansion forces would be lower in the WTC without analysis? Do you think it's a general rule?

No. And I haven't seen any evidence of columns being "pulled in" on a large scale either.

I'm not sure why exactly you deny these images, but here goes:

Originally posted by exponent

No. And I haven't seen any evidence of columns being "pulled in" on a large scale either.

I'm not sure why exactly you deny these images, but here goes:

How are those evidence of columns being pulled in?

Couldn't you be simply seeing the aluminum cladding bowed inwards?

Makes more sense than sagging trusses pulling in more massive columns. The fact that they're sagging due to heat expansion should show you that any movement would all be in the trusses themselves, not the more massive columns they're attached to.

'Equal opposite reactions', the trusses push against the columns, the columns push back with the same force.
The columns were more massive than the trusses, it doesn't require Einstein to tell us the outcome, Newton will do.

BTW, I hope you realise the cladding was not placed directly on the steel? There would have to be a gap due to galvanic corrosion, dissimilar metals can not be placed together. That is all you are seeing, the aluminum is pushed up against the columns from impact and heat.

Originally posted by ANOK
How are those evidence of columns being pulled in?

Couldn't you be simply seeing the aluminum cladding bowed inwards?

No, those pull-in estimates are in inches. The cladding was offset only by a tiny amount.

Makes more sense than sagging trusses pulling in more massive columns. The fact that they're sagging due to heat expansion should show you that any movement would all be in the trusses themselves, not the more massive columns they're attached to.

The vast amount of office materials and furnishings etc would all have been sitting on the trusses, this is the driving force behind any pull-in force.

'Equal opposite reactions', the trusses push against the columns, the columns push back with the same force.
The columns were more massive than the trusses, it doesn't require Einstein to tell us the outcome, Newton will do.

This principle only works as a dismissal until you reach the ultimate load of the elements. This occurred on 911 as the combined inward force of several trusses sagging resulted in the columns exceeding their maximum.

BTW, I hope you realise the cladding was not placed directly on the steel? There would have to be a gap due to galvanic corrosion, dissimilar metals can not be placed together. That is all you are seeing, the aluminum is pushed up against the columns from impact and heat.

I don't know how true this is, I've heard it bandied around the truth movement for some time, but I found no real evidence to support it. Regardless, the cladding was not placed far from the steel, the square profile you see on the outside of the building reflected the actual steel structure. It alone could not account for the pull-in visible, nor would there be a mechanism for the aluminium to be 'pushed up' on the other side of the tower to the impact.

Originally posted by exponent

Originally posted by bsbray11
Well I'll still be here when you're reading to point out what information either I or the scientists involved with that study were ignoring, when they formed their conclusion and wrote it all out, like I just posted on the other page.

Could you please link me to that? I had a look through your posts in this thread but there are 15 pages of them and I couldn't see it specifically.

The key findings of the project can be summarised as:

* The composite steel framed building tested exhibited inherently stable behaviour under the tested fire scenarios due to the highly redundant nature of the structural form.
* This behaviour is characterised by several thermo-mechanical phenomena, which interact. This complex interaction is highly dependent upon the structural layout and the thermal regime of the fire compartment considered.

guardian.150m.com...

These were very thorough tests, as described:

The main objective of the project can be stated as:

`To understand and exploit the results of the large scale fire tests at Cardington so that rational design guidance can be developed for composite steel frameworks at the fire limit state'

This objective was achieved by:

* Developing rigorous, robust finite element models using state of the art, commercial finite element modelling programmes. These models were thoroughly validated using the results of the major Cardington fire tests.
* Developing properly validated, computationally efficient, simplified models to accurately predict the behaviour of multi-storey steel frame structures under fire conditions. These models were developed using both commercial and research finite element packages by an iterative process of comparison with rigorous models and experimental data.
* Developing different models of the same phenomena independently, in parallel to test model sensitivities and modelling assumptions.
* Developing methods of post-processing results so that the underlying structural mechanics can be more easily understood.
* Using the simplified models to conduct parametric studies to explore changes of structural behaviour.
* Checking the consistency of model results with the fundamental principles of structural mechanics by developing appropriate theory.

At the end they list different ranges of temperatures and the different phases the structure goes through based on their research.

If only NIST had been this logical, straightforward, and thorough, we wouldn't even be having this discussion.


That's a mirror from the Guardian. The actual website for the Cardington tests is here:

www.mace.manchester.ac.uk...

The related Broadgate tests were summarized in this PhD thesis:

The Broadgate fire was introduced in Chapter 1 of this thesis. Structural damage caused by the fire included distortion of a number of trusses and universal beams and axial shortening of five columns by 100mm. The deflection of the trusses produced dishing of the floor of up to 600mm relative to the columns. The concrete floor slab separated from its metal decking in some areas but generally followed the level of its deflected supporting members. Despite large deflections, the structure behaved well and there was no collapse of any of the columns, beams or floors. [115]

The behaviour of the structure and the floor members showed that a steel frame designed to BS 5950 Part 8 is structurally safe when exposed to a severe fire. The study [115] carried out after the Broadgate fire showed that when fire affects only part of a structure (compartmentation) and when the framework acts as a total entity structural stability is improved.

Detailed studies of the material properties at high temperatures were carried out and it was concluded that apart from the concrete to the first floor no material showed significant loss of strength due to the fire. Detailed metallurgical investigations were carried out to asses the temperatures reached by the quenched and tempered bolts recovered from several of the beam to column connections in the areas of the fire which showed most damage. These indicated that the most severe temperatures achieved by the bolts during the fire or during manufacture were limited to 540°C. Similar evidence from a truss indicated that the member had been heated to around 600°C. The principles of BS5950 Part 8 would suggest that these members would transfer load to cooler parts of the structure until temperatures of about 700~800°C but the investigations suggest that the temperatures achieved did not exceed 600°C so an alternative explanation for the deformations observed was needed.

guardian.150m.com...

You realize this is the exact opposite direction of the force NIST hypothesized to initiate "collapse," right?

Yes? I don't see why you think that is a problem, NIST also did not as it is included in NCSTAR 1-6C

NIST included a lot of information that didn't agree well with their own hypothesis, and ignored even more, but I only find that as another reason for a real investigation.

For all these differences you still can't tell me how it would mean a smaller force can cause more displacement than an even larger force. The differences are noted, and they're also apparently inconsequential to the point here, which is that the expansion forces are significantly larger than any "pull" force, and at even lower temperatures.

These forces are determined by different things, expansion is determined by temperature, wheras pull in is also determined by the floor loading. How can you say that the expansion forces would be lower in the WTC without analysis? Do you think it's a general rule?

First of all the expansion forces are greater than any "pull" forces, not "lower," so that was a typo I guess. That's according to the only source posted so far, by PLB. I was going off memory from what I read of these reports, and they mentioned no significant "pulling" forces either.

If you want a specific analysis for the WTC, why didn't NIST do one? I can only imagine. I don't see any reason why it should show that any "pull" forces should have been greater than the forces created by thermal expansion. Read those studies and you'll notice there is no evidence of steel itself being heated much beyond 700 C. The temperatures required to reverse expansion forces are 800 C and beyond. NIST found no evidence of this, neither is there any evidence in these studies that it realistically happens. The fire itself is typically 800 C at most, excepting flashover conditions which are brief. And the temperatures required for maximum thermal expansion forces are significantly less.

I'm not sure why exactly you deny these images, but here goes

First of all, where is all the outward expanding we should be seeing, according to all the science posted on this thread already?

It happens at greater forces and at lower temperatures, meaning it should be more visible and sooner. So where is it?

Secondly, what you are actually looking at, in the first photo especially, is predominantly aluminum cladding, not the actual exterior columns. So when you disregard all that cladding jutting out at odd angles and badly mangled, look at what's left. They are not showing you enough perimeter column deflection to seriously endanger the entire floor even by their own admission that the perimeter columns retained 4/5 of their reserve capacity on the morning of 9/11. That equates to a safety factor of 5 and if you haven't seen this already then just say the word and I'll go dig up my old thread where I showcased the NIST excerpt confirming this.

Also heat fields distort light and this is an unfortunate fact. I'm assuming all the deflection they actually show is really there, and it's still not enough to cause a whole floor to collapse given that the perimeter columns there had a safety factor of 5. But in reality what NIST is labeling as buckled columns may be light distorted by the changes in air temperature between the fire and the photographer.

But still more importantly to me, and ignoring the aluminum cladding and the effects of heat on light, and assuming the buckling they show is all there, their explanation also still defies all the science posted here so far, that would indicate more significant deflections outwards should have been observed, and sooner.

Lastly, also assuming the buckling they show is really all there, they don't rule out the possibility that it was caused by any other mechanism, because they considered no other mechanisms.

So those reasons together make up one summary as to why those photographs are inadequate for validating NIST's hypothesis.

Originally posted by bsbray11
These were very thorough tests, as described:
...
At the end they list different ranges of temperatures and the different phases the structure goes through based on their research.
If only NIST had been this logical, straightforward, and thorough, we wouldn't even be having this discussion.

Yes if only NIST had performed real-world tests or examined connections or trusses or columns or hold on one second. They did actually do all of this, so once again you are trying to sneak in some unwarranted criticism. No real shock there because they represent your opponents but a good example of bias again.

I was hoping you'd have some more specific conclusion, but all I wanted to check was that you were talking about beams attached via shear connectors to the columns. These behave quite differently to the trusses would in the towers.

NIST included a lot of information that didn't agree well with their own hypothesis, and ignored even more, but I only find that as another reason for a real investigation.

You find them including information that didn't agree well to be a reason for more investigation? Strange approach.

First of all the expansion forces are greater than any "pull" forces, not "lower," so that was a typo I guess.

Yup, whoops.

That's according to the only source posted so far, by PLB. I was going off memory from what I read of these reports, and they mentioned no significant "pulling" forces either.

Well, there's no denying that there will be pulling forces, once the beams or trusses have sagged enough that they become unrestrained (in the sense that their length including the curve is equal to their expanded size under temperature)

The question was: do you think that it is a general rule that the pushing forces are always higher than the pulling forces. Can you demonstrate this?

If you want a specific analysis for the WTC, why didn't NIST do one? I can only imagine.

They did.

I don't see any reason why it should show that any "pull" forces should have been greater than the forces created by thermal expansion. Read those studies and you'll notice there is no evidence of steel itself being heated much beyond 700 C. The temperatures required to reverse expansion forces are 800 C and beyond.

So if we replace a short span beam with a 45 foot truss, then fire a few of them, what will occur? Please show us how you work it out.

NIST found no evidence of this, neither is there any evidence in these studies that it realistically happens. The fire itself is typically 800 C at most, excepting flashover conditions which are brief.

Woah woah woah. Just a minute ago you didn't know if NIST did the tests, now you know they did and their conclusions? I think not. Please read their experimental tests of office compartments so you can stop imagining temperatures you prefer and believing that it's true.

The typical maximum temperature of these fires was over 1000C, I have no clue where you get 800C from.

And the temperatures required for maximum thermal expansion forces are significantly less.

Uh, so at anything above that the pull in forces will develop, although you just said they couldn't. Confusing.

First of all, where is all the outward expanding we should be seeing, according to all the science posted on this thread already?

It happens at greater forces and at lower temperatures, meaning it should be more visible and sooner. So where is it?

It's restrained, it actually helps to increase the sag of the trusses by stopping them expanding.

Secondly, what you are actually looking at, in the first photo especially, is predominantly aluminum cladding, not the actual exterior columns. So when you disregard all that cladding jutting out at odd angles and badly mangled, look at what's left. They are not showing you enough perimeter column deflection to seriously endanger the entire floor even by their own admission that the perimeter columns retained 4/5 of their reserve capacity on the morning of 9/11.

This is a concentrated paragraph of rubbish. You're not looking predominantly at the aluminium cladding, the cladding did as it was called, it clad the steel, as in it surrounded it on 3 sides and matched the profile. There is no reason nor mechanism to believe that the cladding is responsible for the deformation and not the steel placed literally inches underneath it.

Secondly, no they didn't retain 4/5th of their reserve capacity. That was live load and as with all columns, severely deflecting them diminishes any load carrying capacity extremely quickly.

That equates to a safety factor of 5 and if you haven't seen this already then just say the word and I'll go dig up my old thread where I showcased the NIST excerpt confirming this.

Go for it, see if you can find the difference between live and dead load while you're at it.

Also heat fields distort light and this is an unfortunate fact. I'm assuming all the deflection they actually show is really there, and it's still not enough to cause a whole floor to collapse given that the perimeter columns there had a safety factor of 5. But in reality what NIST is labeling as buckled columns may be light distorted by the changes in air temperature between the fire and the photographer.

As you're so fond of diagrams, please draw this out so we can visually appreciate your argument. The refraction caused by temperature differences is easy to calculate.

But still more importantly to me, and ignoring the aluminum cladding and the effects of heat on light, and assuming the buckling they show is all there, their explanation also still defies all the science posted here so far, that would indicate more significant deflections outwards should have been observed, and sooner.

Why if only you'd actually read the science available, rather than just assuming you understand the behaviour of this immensely complex structure. You'd know that the initial phases occurred before significant truss -> perimeter disconnection, and that the restraining effects of several hundred trusses were enough to stop serious outward deflection, although some undoubtedly occurred. The inward deflection comes later, and is the result of the damage towards large numbers of trusses.

Lastly, also assuming the buckling they show is really all there, they don't rule out the possibility that it was caused by any other mechanism, because they considered no other mechanisms.

You're right, they didn't consider any other mechanism. Funny that. I've been asking you for years to come up with one, and you still haven't, so what exactly do you expect NIST to test?

So those reasons together make up one summary as to why those photographs are inadequate for validating NIST's hypothesis.

Right, you don't like their conclusions, so you grasp at straws to deny them. I mean come on, 'cladding damage'? You're a fool to yourself if you believe that.

Originally posted by exponent
Yes if only NIST had performed real-world tests or examined connections or trusses or columns or hold on one second. They did actually do all of this, so once again you are trying to sneak in some unwarranted criticism. No real shock there because they represent your opponents but a good example of bias again.

Then would you do me a favor, and post the information related to NIST doing all of this?

NIST did do real, physical experiments. But they didn't result in the mechanism they hypothesized. So how does that help NIST's case, when it already contradicts these other studies? If you post the information you're talking about maybe you can see this.

patapsco.nist.gov...

There's a video of NIST performing fire tests.

Do you already know what the results were? (Hint: no columns were pulled in, even with trusses heated to 700 C by a megawatt burner.)

I was hoping you'd have some more specific conclusion, but all I wanted to check was that you were talking about beams attached via shear connectors to the columns. These behave quite differently to the trusses would in the towers.

I don't care if they are different. I want to know how they would make thermal expansion the smaller force, and the "pull" force significantly larger, and at lower temperatures.

Whether it's a beam or truss, I hope we can at least agree that heat is going to make it expand just the same, and that expansion is going to be accompanied by a force that is pushing outwards. Why should that be different at the WTC?

If you can't show how that would have been different at the WTC, then any other differences you point out are inconsequential and meaningless to this discussion.

NIST included a lot of information that didn't agree well with their own hypothesis, and ignored even more, but I only find that as another reason for a real investigation.

You find them including information that didn't agree well to be a reason for more investigation? Strange approach.

Yes. If all the information agreed with their hypothesis, that would be good. When so much information contradicts their hypothesis, that's considered bad for their hypothesis.

That's according to the only source posted so far, by PLB. I was going off memory from what I read of these reports, and they mentioned no significant "pulling" forces either.

Well, there's no denying that there will be pulling forces, once the beams or trusses have sagged enough that they become unrestrained

There's no denying that the temperatures required for that are much greater than for simple thermal expansion.

There's also no question that you have presented absolutely zero evidence to suggest that the thermal expansion phase should have been completely bypassed, and the WTC went straight to the trusses "pulling" on the perimeter columns. Yet this seems to be the position you're trying to dance around like a ballerina. It's not easy, is it?

The question was: do you think that it is a general rule that the pushing forces are always higher than the pulling forces. Can you demonstrate this?

I don't have to demonstrate something on your behalf, when you are the one trying to lend credibility to NIST's report. But maybe I am mistaken and we can simply agree that NIST's report is not conclusive and lacks critical evidence to support it. Otherwise, your burden, not mine, sorry.

If you want a specific analysis for the WTC, why didn't NIST do one? I can only imagine.

They did.

Post what you're talking about and show how it helps your argument.

I don't see any reason why it should show that any "pull" forces should have been greater than the forces created by thermal expansion. Read those studies and you'll notice there is no evidence of steel itself being heated much beyond 700 C. The temperatures required to reverse expansion forces are 800 C and beyond.

So if we replace a short span beam with a 45 foot truss, then fire a few of them, what will occur? Please show us how you work it out.

Again, a lack of evidence on your part is not my problem. I take this as an admission that you are arguing from ignorance and have no real case as to what exactly caused the WTC to "collapse."

NIST found no evidence of this, neither is there any evidence in these studies that it realistically happens. The fire itself is typically 800 C at most, excepting flashover conditions which are brief.

Woah woah woah. Just a minute ago you didn't know if NIST did the tests, now you know they did and their conclusions? I think not.

NIST did not, ever, physically validate their hypothesis. Period. They tried various things, mostly computer simulations to try and find a "realistic" scenario, but that's it. If you want to contradict me by posting anything you'd like from the NIST report, I'd be more than happy to address whatever you have.

Please read their experimental tests of office compartments so you can stop imagining temperatures you prefer and believing that it's true.

The typical maximum temperature of these fires was over 1000C, I have no clue where you get 800C from.

That "over 1000 C" is a flashover condition. This is not new information only available after 9/11. It is not a mystery how hot fires burn, nor any reason to think the WTC Towers should have been any hotter than any open-atmosphere hydrocarbon fire anywhere else. 1000 C is not typical of all the fires for the whole duration and you even say yourself this is a maximum temperature (again, flashover conditions). If 1000C is a maximum, where do you think the general figure of 800 C came from?

I'm arguing against NIST, so feel free to use their data against me.

And the temperatures required for maximum thermal expansion forces are significantly less.

Uh, so at anything above that the pull in forces will develop, although you just said they couldn't. Confusing.

They can't, unless the steel itself is considerably over 700 C. Now you have to recognize that the temperature of the fire, is not the same, as the temperature, of the steel. I would hope you already realize this but maybe not. Also there is data in the studies linked above, as well as from NIST, as to how hot the steel could have gotten according to various evidence.


And, uh, so, where's all the photos of columns pushed out by thermal expansion?

First of all, where is all the outward expanding we should be seeing, according to all the science posted on this thread already?

It happens at greater forces and at lower temperatures, meaning it should be more visible and sooner. So where is it?

It's restrained, it actually helps to increase the sag of the trusses by stopping them expanding.

The sagging itself is not what results in the "pull" force, obviously, since it's created in the first place by a "pushing" force when there is nowhere for the beam/truss to go.

So you think they're restrained in only one direction apparently, and not restrained in the opposite direction. Maybe you know something about the spandrel plates that I don't. Can you explain why the same resistance wouldn't apply to a smaller force applied in the opposite direction please? Otherwise this argument is baseless.

Secondly, what you are actually looking at, in the first photo especially, is predominantly aluminum cladding, not the actual exterior columns. So when you disregard all that cladding jutting out at odd angles and badly mangled, look at what's left. They are not showing you enough perimeter column deflection to seriously endanger the entire floor even by their own admission that the perimeter columns retained 4/5 of their reserve capacity on the morning of 9/11.

This is a concentrated paragraph of rubbish. You're not looking predominantly at the aluminium cladding, the cladding did as it was called, it clad the steel, as in it surrounded it on 3 sides and matched the profile. There is no reason nor mechanism to believe that the cladding is responsible for the deformation and not the steel placed literally inches underneath it.

No reason nor mechanism?



[atsimg]http://files.abovetopsecret.com/images/member/ef2b3bddb899.gif[/atsimg]


The "reason" is because they weren't attached firmly enough, and the "mechanism" is the plane impacts.

The cladding shown above hanging off in all directions, obviously no longer "matched the profile" of the columns. You can no longer judge the position of all the columns by looking at the aluminum cladding which in some cases is hanging straight out off the building.

If you're not intelligent enough to be able to realize the above, then you can keep telling me that this point is "concentrated rubbish." That's fine.

Secondly, no they didn't retain 4/5th of their reserve capacity. That was live load and as with all columns, severely deflecting them diminishes any load carrying capacity extremely quickly.

After reaching the yield strength, structural steel components continue to have significant reserve capacity, thus allowing for load redistribution to other components that are still in the elastic range.

On September 11, the towers were subjected to in-service live loads, which are considered to be approximately 25 percent of the design live loads.

On September 11, the wind loads were minimal, thus allowing significantly more reserve capacity for the exterior walls (demand on exterior columns was about 1/5 their capacity).

wtc.nist.gov...

They were subject to 1/4 their design live loads, and about 1/5 of their capacity, according to NIST as you can read above.

Now this is before impact, so no, they didn't retain that 1/5 capacity. But they did retain some reserve capacity, until that 5x redundancy was totally reduced to 1x redundancy, ie just being able to carry their design loads. If the whole floor columns never reached that point then there is no theoretical grounds for them to have collectively failed.

That equates to a safety factor of 5 and if you haven't seen this already then just say the word and I'll go dig up my old thread where I showcased the NIST excerpt confirming this.

Go for it, see if you can find the difference between live and dead load while you're at it.

I already understand the difference, so now let's see if you can read, or realize how they can't be saying the columns were at 1/4 of their live load capacity and 1/5 of their live load capacity at the same time. Obviously that would make no sense, and they don't specify live load for the 1/5 number. They just say "capacity." I'll let you try to make sense out of this on your own. It already makes sense to me.

As you're so fond of diagrams, please draw this out so we can visually appreciate your argument.

No thanks. I already had to use MS Paint for you once in this post, to point out what you were too blind to see. Hire a teacher to draw pictures for you.

The refraction caused by temperature differences is easy to calculate.

Then you wouldn't need me to draw you a picture if you wanted to prove me wrong, would you?

Why if only you'd actually read the science available, rather than just assuming you understand the behaviour of this immensely complex structure. You'd know that the initial phases occurred before significant truss -> perimeter disconnection, and that the restraining effects of several hundred trusses were enough to stop serious outward deflection, although some undoubtedly occurred. The inward deflection comes later, and is the result of the damage towards large numbers of trusses.

You can't claim that outward expansion would have been almost completely restrained, but a "pull" force could just runaway completely unrestrained, especially without evidence. This is in none of the studies here.

It's easy to claim I don't understand the reports. Then you turn around and say something that's in none of them happened at the WTC. Why should I believe you? You're obviously trying very hard to force a conclusion that is nowhere to be found in any of the scientific literature posted so far on this thread.

Lastly, also assuming the buckling they show is really all there, they don't rule out the possibility that it was caused by any other mechanism, because they considered no other mechanisms.

You're right, they didn't consider any other mechanism. Funny that. I've been asking you for years to come up with one, and you still haven't, so what exactly do you expect NIST to test?

They could have started with testing for explosives residues, especially given all the witness accounts of explosions. And stop before you start making excuses for the explosions, because that's not how science works. You don't hear witness testimonies of explosions, and immediately start making excuses so you don't have to test. That is only retarded 9/11 "thinking" that a lot of zealous OS believers employ. For any other event, if people heard numerous explosions, and it was a "terrorist attack," and there had been explosives detonated there before already, of course there would be testing for various forms of explosives. Instead all of this information enters a warped head, and comes out as some kind of reason not to ever test for them, almost as if you are willingly making excuses to protect the perpetrators.

So those reasons together make up one summary as to why those photographs are inadequate for validating NIST's hypothesis.

Right, you don't like their conclusions, so you grasp at straws to deny them. I mean come on, 'cladding damage'? You're a fool to yourself if you believe that.

The aluminum cladding is not what does the NIST report in. It's the fact that they never proved their hypothesis anyway. I don't even have to try to deny what isn't there in the first place.


You should be using all the studies posted on this thread to show how NIST's hypothesis was justified, but instead you're having to make excuses about why these different studies say the exact opposite of NIST. If you want to talk about being a fool then you can start with that, because I'm still not seeing you post any evidence that NIST was correct despite being so out-of-line with these other studies.

reply to post by exponent


Pay careful attention to this...

There is fairly broad agreement in the fire science community that flashover is reached when the average upper gas temperature in the room exceeds about 600°C. Prior to that point, no generalizations should be made: There will be zones of 900°C flame temperatures, but wide spatial variations will be seen.

Now...

Of interest is the maximum value which is fairly regularly found. This value turns out to be around 1200°C, although a typical post-flashover room fire will more commonly be 900~1000°C. The time-temperature curve for the standard fire endurance test, ASTM E 119 [13] goes up to 1260°C, but this is reached only in 8 hr. In actual fact, no jurisdiction demands fire endurance periods for over 4 hr, at which point the curve only reaches 1093°C.

And...

It is common to find that investigators assume that an object next to a flame of a certain temperature will also be of that same temperature. This is, of course, untrue. If a flame is exchanging heat with a object which was initially at room temperature, it will take a finite amount of time for that object to rise to a temperature which is 'close' to that of the flame. Exactly how long it will take for it to rise to a certain value is the subject for the study of heat transfer. Heat transfer is usually presented to engineering students over several semesters of university classes, so it should be clear that simple rules-of-thumb would not be expected. Here, we will merely point out that the rate at which target objects heat up is largely governed by their thermal conductivity, density, and size. Small, low-density, low-conductivity objects will heat up much faster than massive, heavy-weight ones.

www.doctorfire.com...

The first tower to fall was on fire for less than one hour. There is no reason to believe the fires would be any hotter than normally expected in open air room fires. The jet fuel would not increase the temps as it burns at a lower temp then the room would be at already, it would only cause objects to burn faster.

1. Not enough time to reach temperatures needed for a flash over.

2. Not enough time for significant heat to transfer to steel columns in order to cause complete failure.