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Originally posted by exponent
Well you're free to speculate all you like, but what is the point? It adds nothing to the discussion and can prove nothing?
The steel in 1975 had no fireproofing damage, the fire was fought and only occupied a relatively small area.
The steel had no fireproofing material on it in 1975 either.
The 1975 fire was not small, as it went from 11 th floor to 19th floor.
There was actually some minor damage which occurred, but it was not too serious.
You can't be making the argument that steel is invulnerable to fire, so you must be (unless I am mistaken!) making the argument that the fires on 911 were not significant enough to damage the steel. How do you resolve this with NISTs tests which do not agree with you?
Originally posted by bsbray11
Originally posted by exponent
These trusses had only a few square inches of contact space to the rest of the steel in the towers, but hundreds of square inches of surface area which was involved in flame.
Just so no one is confused, NIST's failure mechanisms only needed trusses to be heated to the point of a certain amount of expansion (which they didn't really define) so that a certain amount of force would be applied laterally to the perimeter columns (also no calculations from NIST for that). Then the perimeter columns are somewhat deflected, and supposedly after so much of this (they also didn't say how many would need to be deflected or by how much) the "global collapse" ensued, which NIST simply called "inevitable," again without showing any work.
Just trying to make it clear that, not even the "official" reports are actually saying heat itself caused actual significant strength loss in the steel columns or even the trusses
Originally posted by Newtons.Bit
I've even done calcs to verify it. newtonsbit.blogspot.com...
In a 600C fire, the Modulus of Elasticity will have reduced to approximately 0.3 of its original value, and the yield strength to 0.5 of its original value.
Originally posted by Griff
Originally posted by Newtons.Bit
I've even done calcs to verify it. newtonsbit.blogspot.com...
In a 600C fire, the Modulus of Elasticity will have reduced to approximately 0.3 of its original value, and the yield strength to 0.5 of its original value.
I see you haven't updated your blog yet as to this sentence. I have to wonder why you word this the way you do.
Wouldn't the correct way to say this be: If the steel becomes 600C.....?
And does that correlate to NIST's own findings?
Originally posted by bsbray11
That's easy: they kept modifying the simulation parameters. If you don't know what I'm talking about already, then someone else can post the relevant part of the NIST report or I can do it later. They assumed a priori that fire and impact damages caused the collapses, and then they kept simulating the fires on computers and increasing the amount of heat until they could start producing failures.
If you're talking about actual lab tests, I would love to see the test where NIST showed expanding trusses deflecting perimeter columns.
Do you have any idea how showing that allows verifying their actual calculations or simulations independently? Why do you think it would be important to consider those kinds of calculations in the first place?
I actually didn't know this. Can you link to it? And does it add this force to the tensions from the spandrel plates and end-to-end connections (which would have tried to hold the columns in place)?
Bazant's work has been criticized for assuming variables where either experimental data or the actual structural documentation needs to be consulted, among other problems. The paper was written 2 days after 9/11, before any investigation whatsoever, and with absolutely no precedent on which to base the physics.
Zdenek Bazant and Yong Zhou must be super-geniuses
But they physically found no evidence for this, or even for heating above around 200-300 C. Not to mention steel glows dark red in broad daylight at this temperature. In general it is an insane temperature to transfer to much steel, because of how much heat energy is required to do it.
Have you ever looked at that math? Would you be willing to or do you find yourself automatically assuming it's wrong and that NIST is still pure?
The steel had no fireproofing material on it in 1975 either.
The 1975 fire was not small, as it went from 11 th floor to 19th floor.
The argument is like this.
...
So no the fires, which I have stated several times, in WTC1-2-7, were insufficient to cause buildings to fall.
Originally posted by Newtons.Bit
The failure mode is that the floor trusses go into tension and, to put it in laymen's terms, act as ropes to support the core columns that are severed.
Originally posted by exponent
No they didn't, what they actually did is take reasonable error margins.
if they actually got failure within reasonable fire temperatures, then your complaint is invalid.
If they manipulated the values outside the acceptable range then your complaint would be valid. Nobody has pointed out the latter despite many attempts.
I'm not sure what exactly you're saying here, NIST have released model data that has been requested via FOIA. The software they use is all available. Why has nobody verified their actual simulations independently?
The first part of this quote is valid, and the last part slips into complete rubbish. While Bazants work did appear quickly, it's not based on unknown physical principles
and since then his work has been repeated with more rigour by people such as Gregory Urich, Dr Frank Greening etc. All of these analyses agree with Bazant.
With regards to your link to 911research, the whole section starts with
Zdenek Bazant and Yong Zhou must be super-geniuses
This is not a serious critique.
I can show you steel in the Cardington tests reaching these temperatures within a few minutes.
It's not insane at all and this is just your personal speculation. Provide some evidence from a non-truther source please.
A floor section was modeled to investigate failure modes and sequences of failures under combined gravity and thermal loads. The floor section was heated to 700 ºC (with a linear thermal gradient through the slab thickness from 700 ºC to 300 ºC at the top surface of the slab) over a period of 30 min. Initially the thermal expansion of the floor pushed the columns outward, but with increased temperatures, the floor sagged and the columns were pulled inward. (p 98/148)
A spray burner generating 1.9 MW or 3.4 MW of power was ignited in a 23 ft by 11.8 ft by 12.5 ft high compartment. The temperatures near the ceiling approached 900 ºC. (p 123/173)
I'm confused as to how NISTs supposedly incorrect math could change how the fires performed in the physical tests they used to verify this.
this was exponents comment:
It's not insane at all and this is just your personal speculation. Provide some evidence from a non-truther source please.
Originally posted by bsbray11
Who decides what's "reasonable"? You?
I asked you if you had seen the numbers on how energetic they assume those fires were, and you completely ignored my question.
The temperatures were not extraordinary, the amount of heat they assumed was.
How would you know?
Maybe a lack of structural documentation has something to do with it. Something to investigate?
No, it isn't, but you don't know that you can apply them so simply to the towers falling, under some kind of assumed collapse mechanism that no one had even established yet. That was my point. There was not, and still isn't, a set of formulas with which you can just crank out a collapse scenario with any degree of certainty that it's going to bear any relation at all to reality.
Computer simulations so far have only offered the first second or so of initiation. Even just the effects of impact-loading in steel structures is something new to engineering, as that was something the FEMA engineer Astaneh-Asl was studying in the lab a month before 9/11 took place.
That's your story. Neither of those people mean anything to me. They're JREF'ers.
Greening is a chemist by trade and I've seen enough garbage from him, from his suggestions of thermite forming on its own in the towers to help bring them down, to dimensionless mathematical "models" of collapse scenarios that neglect just about everything you possibly could just to prove a (meaningless) point.
Too good for sarcasm? Really? I thought they brought up good points, whether or not you refuse to consider them. We'll all just keep having disagreements so long as you keep avoiding what really stands out as "wrong" to us.
Yeah, but they were intentionally high-powered fires, which wasn't the case at the WTC. They did other tests at Cardington where it took 30 minutes or longer for segments (of MUCH THINNER) steel to reach those temperatures. What do you think made the difference?
Here's the NIST excerpts:
Look up the power ratings for wood stoves. Let's say we use a 1500-watt stove as the reference (decently sized, look them up). So 1.9 MW of power is equivalent to over 1250 of these stoves. 3.4 MW is over 2250 of them.
So you think the fires in the WTC towers on 9/11 must have been equivalent to the energy of between 1250 and 2250 wood stove fires, per living-room size area. Right?
Can you tell me where in the report they reproduced the collapse mechanism in a lab?
Originally posted by exponent
In fact NISTs SAP2000 model gives you pretty much all the information you need to simulate the towers.
Well there's no denying that, nobody is claiming to know 100% of what is going on, simply that we have a very good explanation of collapse without need to invoke any supernatural elements like nano thermite or space beams.
We can explain impacts, structural weakening and eventually collapse quite well with only things we have direct evidence for.
and contains facts we can show are wrong (the idea that a 5 to 1 safety ratio is common). It is just speculation without any actual science to back it up.
Of course they did not do this. Do you believe this is the only way to sufficiently verifiy their conclusions, or would you accept some more reasonable evidence?
Originally posted by Griff
Again, this is not what we are saying.
What we are saying is: It is impossible to peer review NIST's work with only NIST's data.
With my green sky analogy again: If I wrote a paper that the sky was green and all you had to go on was a picture that I painted with the sky being green, could you say my paper was false?
Neither of which are "supernatural".
Only if your evidence shows heating to a certain temperature. Does it?
That is not the idea as far as I'm concerned. I believe the idea is that since the wind load would place a tremendous load on the exterior in hurricane force winds, by design, those exterior columns would have a high safety margin. Now, since the day wasn't windy, that reserve would be used for other loads. But, I will agree it's probably not 2000% more.
It's not unreasonable to ask for empirical proof in the scientific method.
Please take my words with kindness also, I usually don't mean to be harsh, but it's difficult to not come accross that way on just internet forums.
Originally posted by exponent
If you presented me a paper, that said essentially "we use this painted picture as evidence the sky is green". I would respond simply "such a painting has no connection with reality, I could not repeat this painting and get the same result.
There likely is no other data available on the construction of the building,
I will help you attain any information you need to recreate this simulation, but I don't understand why you don't think it's possible.
Actually they both are. Nano-thermites are cited as being able to create high explosive like blast effects, thermite like heat effects, all while being silent. These things are mutually exclusive, therefore supernatural.
Space beams exceed maximum power limits and there is no physical mechanism for 'dustification', therefore supernatural.
Actually no you are correct that some of the live loads may have had huge amounts of safety margin, but the dead loads certainly did not. I'm not sure if the claims are intrinsically linked but they are both wrong, perhaps for different reasons.
No it's not, but it is unreasonable to expect NIST to build any sort of large scale reproduction of the towers and attempt to reproduce conditions that day. I am sure you can't disagree with me on this can you?
Noted, I do respect the fact you're an engineer, but if you look at what some of the people with appropriate credentials have said it makes you doubt. Argument by authority is not strong, and I'm glad you haven't fallen into the trap
Originally posted by exponent
Originally posted by bsbray11
Who decides what's "reasonable"? You?
No, the data
coupled with engineer opinion
There are plenty of fire, impact, collapse etc simulations.
They are quite simplistic, 1d models, but they do match the observations.
Well there's no denying that, nobody is claiming to know 100% of what is going on, simply that we have a very good explanation of collapse
Greening is also the source for your claims about heat output above as far as I know.
Disparaging sarcasm indicates a rather poor bias, the page you're referring to has no calculations
and contains facts we can show are wrong (the idea that a 5 to 1 safety ratio is common)
Can you show me a single instance of that? Even in the smallest fires last time I looked steel temperatures rose extremely rapidly.
No, you do not understand the purpose of these tests. Please go back and re-read what they were using them for.
Can you tell me where in the report they reproduced the collapse mechanism in a lab?
Of course they did not do this. Do you believe this is the only way to sufficiently verifiy their conclusions, or would you accept some more reasonable evidence?