Frank Greening submits withering critique of new WTC7 drafts

[Tbone]

And on Sept 11th no less! The coincidences are piling up!

 

[DC]

Have you considered filing a FOIA request for the ANSYS/LS-DYNA models? NIST released the SAP2000 models of the WTC towers so it should be possible to get them.

Unfortunately then you're missing the 6 months it takes to run the LS-DYNA model, but at least you can verify as much as possible.

i am indeed thinking about it.
but i have not much trouble with the collapse sim itself, when the pictures are without deflection scales.

 

[DC]

finaly i got an answer from NIST

Dear Mr. ______________,



Thank you for your inquiry regarding the analysis of the collapse of World Trade Center 7. In answer to your questions regarding displacement scaling, there was no displacement scaling in any of the figures shown for the ANSYS analyses (NCSTAR 1-9, Chapter 11) or the LS-DYNA analyses (NCSTAR 1-9, Chapter 12 and NCSTAR 1-9A). With respect to the large deflection (NLGEOM) this was set to to “ON” so that large deflection effects were captured by the analyses. I hope this answers your questions.



Regards,



Steve Cauffman

From: Daniel _____________
To: Shyam Sunder
Sent: Thu Sep 18 06:14:26 2008
Subject: FE Analysis of WTC7 another attempt to get an Answer

Dear Dr. Sunder

I have a few questions about the "Global Structural Analysis of the Responce of World Trade Center Building 7 to Fires and Debris Impact Damage".

http://wtc.nist.gov/media/NIST_NCSTAR_1-9A_for_public_comment.pdf

In particular about the Ansys LS-Dyna FE Analysis.

In Figure 4-18 to 4-35 (Page 80-90) and Figure 4-43 to 4-62 (Page 95-108).

Is there any displacement scaling in those Figures?
I assume that the Ansys setting DMULT was set to 1 (DMULT = 1) in your Analysis, so the displacement was not scaled.
Is this correct?
I also Assume the large-deflection key (NLGEOM) was set ON (NLGEOM=ON) so the large deflection effects was not ignored.
Is this correct?

Did NIST use any deflection scales without mentioning it and/or without mentioning the deflection scale in the WTC7 Report(s)?

thank you for your answers
with kind regards

Daniel _________
__________________________
Muttenz, Switzerland

 

[Max Photon]

When the scales fall from their eyes

I am so damn tired of people who have an axe to grind completely misinterpreting FEM and FEA. Dr Greening is an ___ --he KNOWS better!
Yes--the buildings absolutely DID look like that. All you have to do is scale it. Max deflection of a FEM is nearly always distorted--intentionally. Normal procedure is to set the scale such that max deflection is 10% of the available screen.
This is done so that you can actually SEE the Relative deflections. If you used actual scale (1"=1"), it wouldn't even show.
Dr Greening is using HIS authority as a chemist to denigrate the actual authorities in the field he is so totally clueless in.

Failed.

I just had to confirm this for myself, because... well... that's what skeptics do, right?

Here's some FEMs of load sets on a bridge:

http://www.nikhef.nl/pub/experiment...ces/images/Bridge/FEM/3d/OTTframe_3D_fem1.png (source)

If I'm reading that right, the distortion is in mere millimeters, but obviously quite visible in the model.

That's from a 2005 report, so the NIST's FEM that Greening takes issue with is hardly unprecedented.

Again, that was me, as a laymen, but I'd have to agree that Greening is being astoundingly and unprofessionally dishonest regarding this point.

(ETA: Oh, hey... that's not a bridge in the traffic sense, but actually a support bridge in the Large Hadron Collider. Neat.)

Failed.

The FEA software that I use regularly at work is called RISA. It scales up deflected shapes by a factor of 40 by default. Why? Because a 1" deflection
on a 40' frame will be about 1 pixel on screen. You'd never even notice it.

This is pretty typical stuff in engineering.

I use FE on a daily basis. I'm working on my own FE program. I think I've used over a dozen different FEA packages. Inlcuding Ansys. Have you ever even used an FEA program much less ANSYS before? I recall them ALL having default deflection amplifcation. Until someone shows a screenshot stating otherwise, I'm going to assume that. I'm not going to trust some truther like you who constantly twists the real-world to meet their own distorted sense of reality.

Failed.

 

[psikeyhackr]

Apollo has landed but can't get up.

Frank Greening's reasoning ability is so impressive.

This is from page 3 of his report:

We begin by noting that live television coverage of the events of 911 show that WTC 1 and WTC 2 collapsed from the structural failure of severely damaged upper floors located close to the aircraft impact points. These impacts are centered at floor 96 for WTC 1 and floor 81 for WTC 2. Thus we assume that a mass of 14 (more or less intact) floors fell onto the remaining 96 (more or less intact) lower floors of WTC 1 and 29 upper floors fell onto 81 lower floors in WTC 2. For the general case of n floors
collapsing we define a collapsing mass Mc :
Mc = n mf ......................... (1)
where mf is the mass of one WTC floor, assumed to be 1/110 the mass of an entire WTC tower, namely mf = (510,000,000 / 110) kg  4,636,000 kg

http://www.911myths.com/WTCREPORT.pdf

He is dividing the total mass of the towers by 110.

But the towers were actually 116 stories tall. There were SIX BASEMENT LEVELS. Doesn't the total mass include the steel and concrete that went into the basements?

Then there is the problem of distribution of mass. Don't the lower levels of skyscrapers have to be stronger to support the weight above? Doesn't that mean more steel toward the bottom therefore the buildings are ALWAYS BOTTOM HEAVY?

So his dividing by 110 means he is assuming an even distribution which puts too much weight is too high so even if all of his equations in the following 25 pages are correct he was plugging THE WRONG DATA into them.

Curious that the nation that put men on the moon can't tell everyone the tons of steel and tons of concrete on every level of buildings designed before the moon landing SEVEN YEARS after their destruction.

psik

 

[Crazy Chainsaw]

Frank Greening's reasoning ability is so impressive.

This is from page 3 of his report:

http://www.911myths.com/WTCREPORT.pdf

He is dividing the total mass of the towers by 110.

But the towers were actually 116 stories tall. There were SIX BASEMENT LEVELS. Doesn't the total mass include the steel and concrete that went into the basements?

Then there is the problem of distribution of mass. Don't the lower levels of skyscrapers have to be stronger to support the weight above? Doesn't that mean more steel toward the bottom therefore the buildings are ALWAYS BOTTOM HEAVY?

So his dividing by 110 means he is assuming an even distribution which puts too much weight is too high so even if all of his equations in the following 25 pages are correct he was plugging THE WRONG DATA into them.

Curious that the nation that put men on the moon can't tell everyone the tons of steel and tons of concrete on every level of buildings designed before the moon landing SEVEN YEARS after their destruction.

psik

OH what fallacy, the basement levels would not have been included in the upper support structure, also, the water tanks and mechanical floor weight is unknown so Greening's estimates are quite conservative.

You do not include the lower foundation, bath tub in the supported mass as it supports and anchors the mass above to the ground.

The 110 stories above the bath tub,(basement) are what fell into the bath tub, the bath tub remained for all intended purposes relatively intact, why then count it in the equations?

 

[GregoryUrich]

OH what fallacy, the basement levels would not have been included in the upper support structure, also, the water tanks and mechanical floor weight is unknown so Greening's estimates are quite conservative.

You do not include the lower foundation, bath tub in the supported mass as it supports and anchors the mass above to the ground.

The 110 stories above the bath tub,(basement) are what fell into the bath tub, the bath tub remained for all intended purposes relatively intact, why then count it in the equations?

CC,

Far from being conservative, the 500,000 tons value is just plain wrong. This however is no fault of Dr. Greening, as that was the best information available at the time. Since he was was calculating the collapse time to ground level, it was correct to use 110 floors. Greening has also shown that the collapse times are relatively insensitive to the mass in the range 300,000 - 500,000 tons. The actual total mass (116 floors) was closer to 320,000 tons, but it turns out that the analytical collapse time still does not give any indication that the towers fell too fast. In fact most commonly used estimates of the actual collapse times (i.e. 12-14 seconds) are probably much too fast. Nearly half the building was still standing at the 11 sec mark.

Psikey,

Did you read Greening's criticism of the WTC7 draft?

 

[DC]

I am so damn tired of people who have an axe to grind completely misinterpreting FEM and FEA. Dr Greening is an ___ --he KNOWS better!
Yes--the buildings absolutely DID look like that. All you have to do is scale it. Max deflection of a FEM is nearly always distorted--intentionally. Normal procedure is to set the scale such that max deflection is 10% of the available screen.
This is done so that you can actually SEE the Relative deflections. If you used actual scale (1"=1"), it wouldn't even show.
Dr Greening is using HIS authority as a chemist to denigrate the actual authorities in the field he is so totally clueless in.

What do you think now about the NIST FEA of WTC7? Now that you know it did not look like the WTC7 Collapse?

I think this would be a great place for an excuse to Dr. Greening for your accusations of him using his authority as a chemist to denigrate the actual authorities in the field, where you thought he is so clueless about.
it turned out that you are the clueless one.


but to be fair i might add that indeed the default setting in all the FEA software packages i know is scaled deflection. Because normally you dont simulate total collapses of buildings. Youu simulate the daily use of constructions. Also in ANSYS the default setting is scaled deflections (max deflection is 5% of the total model length). But that default changes when you have the correct settings for total collapse sim.

But when you have a little understanding of FE, you know a scaled simulation of a total collapse makes no sence.
you would use scales for sims like earthquakes or a wind analysis, but sure not for a total collapse.

and the pictures from a FEA are totaly useless when you dont know the deflection scale or the max deflection.

 

[psikeyhackr]

OH what fallacy, the basement levels would not have been included in the upper support structure, also, the water tanks and mechanical floor weight is unknown so Greening's estimates are quite conservative.

Provide a link to where someone has separately specified the above ground and below ground masses of a WTC tower. Greening is using 510,000,000 kg, which is 561,000 tons. By dividing by 110 he is assuming all of that was above ground.

That is high compared to what Gregory Urich says.

psik

 

[DC]

Provide a link to where someone has separately specified the above ground and below ground masses of a WTC tower. Greening is using 510,000,000 kg, which is 561,000 tons. By dividing by 110 he is assuming all of that was above ground.

That is high compared to what Gregory Urich says.

psik

greenings calcs are from the time where the weight of the towers was estimated around 500 000 tons each.

Urichs paper about the weight,a far better and more precise estimation of the weight, came later afaik.

Urichs estimation seems to be by far the best avaible, but it is still not what you are looking for, because he did indeed use interpolation because there is not much detailed information, but he used all the avaible data.

but this topic is about Dr. Greenings critique about WTC7 report. there are several WTC 1 and 2 topics. Dont derail this one pls.

 

[DC]

What do you think now about the NIST FEA of WTC7? Now that you know it did not look like the WTC7 Collapse?

I think this would be a great place for an excuse to Dr. Greening for your accusations of him using his authority as a chemist to denigrate the actual authorities in the field, where you thought he is so clueless about.
it turned out that you are the clueless one.


but to be fair i might add that indeed the default setting in all the FEA software packages i know is scaled deflection. Because normally you dont simulate total collapses of buildings. Youu simulate the daily use of constructions. Also in ANSYS the default setting is scaled deflections (max deflection is 5% of the total model length). But that default changes when you have the correct settings for total collapse sim.

But when you have a little understanding of FE, you know a scaled simulation of a total collapse makes no sence.
you would use scales for sims like earthquakes or a wind analysis, but sure not for a total collapse.

and the pictures from a FEA are totaly useless when you dont know the deflection scale or the max deflection.

little bumb for rwguinn

 

[Crazy Chainsaw]

Provide a link to where someone has separately specified the above ground and below ground masses of a WTC tower. Greening is using 510,000,000 kg, which is 561,000 tons. By dividing by 110 he is assuming all of that was above ground.

That is high compared to what Gregory Urich says.

psik

DR. Greening I believe used the figures provided by the society of engineers, on the above ground mass.
They neglected to tell him that the 500,000 ton number included he bath tub, as I recall.

 

[Crazy Chainsaw]

CC,

Far from being conservative, the 500,000 tons value is just plain wrong. This however is no fault of Dr. Greening, as that was the best information available at the time. Since he was was calculating the collapse time to ground level, it was correct to use 110 floors. Greening has also shown that the collapse times are relatively insensitive to the mass in the range 300,000 - 500,000 tons. The actual total mass (116 floors) was closer to 320,000 tons, but it turns out that the analytical collapse time still does not give any indication that the towers fell too fast. In fact most commonly used estimates of the actual collapse times (i.e. 12-14 seconds) are probably much too fast. Nearly half the building was still standing at the 11 sec mark.

Psikey,

Did you read Greening's criticism of the WTC7 draft?

Yes I did, and I believe that Dr. Greening is right to ask for some clarifications from NIST.

 

[DC]

This reminds me of an anecdote by George Mikes to illustrate certain German national tendencies, in which he related the story of two men on a station platform arguing what was the quickest way to travel from Frankfurt to Munich by train, but refusing to look at the timetable because they preferred to reason their cases from first principles. Might it be a good idea for someone to ask NIST what deflection scaling they actually used in the diagram, or would that somehow spoil the fun?

Dave

well i didnt think so but now i have to agree, it spoled all the fun

the topic is isnored to death now....

 

[e^n]

well i didnt think so but now i have to agree, it spoled all the fun

the topic is isnored to death now....

It does "spoil the fun" a little, as it gives truthers another vector of attack. It was always obvious that NISTs FEA would become less accurate as it progresses, but it is unfortunate it does not match particularly well this early in collapse.

There can be no denying that the east wall did exhibit the behaviours they note, but not with any great accuracy.

Just thought I would post an acknowledgement of this fact because I know how some theorists like to make sweeping claims.

DC, my best advice to you would be to request these models, I don't know what the truth movement's financial capabilities are, but requesting donations to contribute to building a computing grid so you can do your own analysis of collapse would be a worthy cause, hell I might even contribute! It's certainly my area of expertise.

 

[DC]

It does "spoil the fun" a little, as it gives truthers another vector of attack. It was always obvious that NISTs FEA would become less accurate as it progresses, but it is unfortunate it does not match particularly well this early in collapse.

There can be no denying that the east wall did exhibit the behaviours they note, but not with any great accuracy.

Just thought I would post an acknowledgement of this fact because I know how some theorists like to make sweeping claims.

DC, my best advice to you would be to request these models, I don't know what the truth movement's financial capabilities are, but requesting donations to contribute to building a computing grid so you can do your own analysis of collapse would be a worthy cause, hell I might even contribute! It's certainly my area of expertise.

thx for your reply.

I am no member of any group. While alot here say i belong to the TM i dont see that organisation. there are several diffrent organisations and each of them do collect money (i love to see them collecting money for the first responders, but the rest is .....).

With the FEA of the collapse i have no troubles at all. it looks like i would expect a fire indicated collapse. but thats not how WTC7 collapse looked to me. So i dont really see the use of rerun the sim.
i think another approach is needed, another theory, the one now does not account for the observed collapse in my oppinion.

i wonder why they left away the FEA with hypotetical blast events, like they told us they will do a few months ago.

But there is the problem, with a FEA of a CD, you have controll of the event, so you can make it look like the WTC7 collapse looked like. thats the way truthers would go.

but NIST is looking for a cause that is not a CD but does account for the observed behavior. Untill now, i think they failed with it.

I think a closer inspection to the Fire sim is more important, but that is not my field.

and about Ansys, i have very limited acces to Ansys, via a friends company, but they use it themself, so i can only get on it when they are not working, but t will be impossible to let run such a complex sim on theyr servers, they need them.

 

[e^n]

thx for your reply.

I am no member of any group. While alot here say i belong to the TM i dont see that organisation. there are several diffrent organisations and each of them do collect money (i love to see them collecting money for the first responders, but the rest is .....).

Well it's tempting to say that you are implicitly a member of the "truth movement" but I am not sure this is fair. We are all looking for the truth after all, just the attitude you take is sometimes worrying as it indicates to us that you may have already decided on what theory is "correct".

i wonder why they left away the FEA with hypotetical blast events, like they told us they will do a few months ago.

I don't know what you mean when you say "left away". They conducted analysis of two seperate blasts resulting from different sized charges which were the minimum required to fail a single column. The indicated overpressures would result in a huge bang being heard well over half a mile away, nothing of the sort was recorded.

But there is the problem, with a FEA of a CD, you have controll of the event, so you can make it look like the WTC7 collapse looked like. thats the way truthers would go.

Potentially yes, but the question is whether you can justify it scientifically. You can take a model of a building and propose that elements are removed, but such a complex structure will exhibit so called "emergent behaviour", that is things will occur in a manner different from what you expect because of the sheer complexity of the system. It took NIST 6 months to run collapse simulations on an array of highly powered machines, so simply speculating as to the locations of charges and then running the simulation from there is unlikely to be productive.

but NIST is looking for a cause that is not a CD but does account for the observed behavior. Untill now, i think they failed with it.

I think a closer inspection to the Fire sim is more important, but that is not my field.

I'm not going to entirely agree or disagree with you here, yes NISTs simulation is not a completely accurate reproduction of the events, but this is because NIST was not attempting to simply replicate the collapse. NIST took the initial variables they were aware of (fire duration etc) and allowed their model to run. This is the only legitimate investigative method, as it runs without human judgement being required after a certain point. These initial assumptions can be challenged, but after that point it is simply down to the quality of simulation.

It is a big topic to cover though so I won't try and describe the process in full here.

and about Ansys, i have very limited acces to Ansys, via a friends company, but they use it themself, so i can only get on it when they are not working, but t will be impossible to let run such a complex sim on theyr servers, they need them.

That's fair enough, you're obviously not obligated to do anything at all until you make positive claims. Still, I don't think you can deny that NISTs simulation, even if relatively inaccurate during global collapse is quite convincing in terms of predicting the observed failure? Simply having the east penthouse collapse first, followed by a general roofline failure a few seconds later is something which should not be possible if the cause of the collapse was CD.

 

[GregoryUrich]

Yes I did, and I believe that Dr. Greening is right to ask for some clarifications from NIST.

I was pretty sure you had, I was asking Psikeyhackr.

 

[Miragememories]

"Well it's tempting to say that you are implicitly a member of the "truth movement" but I am not sure this is fair. We are all looking for the truth after all, just the attitude you take is sometimes worrying as it indicates to us that you may have already decided on what theory is "correct"."

If we are ALL looking for the truth as you say, I suggest you stop using the term "truther" as a label to discriminate against those who "worry you" through disagreement.

MM

 

[e^n]

If we are ALL looking for the truth as you say, I suggest you stop using the term "truther" as a label to discriminate against those who "worry you" through disagreement.

Leaving aside the fact you have not accurately represented my post, in what manner am I discriminating MM?

You are quick to criticise, but in the 7 years since 911 has passed you seem to have done little but sit on the sidelines and snipe at people.