Architects, Engineers, and Scientists Analyze Failings of NIST's WTC 7 Final Report!

Originally posted by Griff
Can I not say the same of NIST? Can I repeat (or even them) this "simulation" in real life?

I'm becoming increasingly confused here!

As I understand FEA, yes. You should be able to construct either a partial or full scale model and as long as the fire and damage applied is within reasonable margins, the structure should perform as the simulations indicate. Surely this is the point of simulation?

Now, if your argument is that you don't have the facilities or capability to verify the FEA then I can't disagree with you. None of us do, which is why NIST was tasked with the investigation. However, you can hardly criticise NIST for this, I cannot imagine how WTC7s collapse could be investigated without large scale simulation.

That's my point. Also, the point of if you had no other reference to the physical reality that the sky is blue...you would have to accept my paper that the sky is green. Because this painting is the only reference available.

Not at all, allow me to extend the analogy however to try and resolve this problem.

The problem with your analogy is that it cannot conform to the scientific method, there is no data to test, nor a mechanism of testing, only the results. Say instead that your analogy proposes a method of testing which you have carried out, and results in a measurement of the sky being green. In this case we would at least have some initial data and a testing mechanism.

If I were to attempt to check your results, we would be in a similar situation as you propose with NIST. Perhaps I cannot obtain original testing data myself, and must reuse your data along with the mechanism presented in order to produce results. In this case I could certainly verify that your mechanism does produce the results you claim for the input conditions.

We already seem to have gone this far with discussion however, and you seemed to agree that NISTs method, if reproduced by a third party using NISTs data, would result in the same conclusions.

However, if this is the case, then we have not reached the limits of testability. NISTs data is not unchallengeable, and indeed a detailed analysis of the original WTC1 and 2 reports has in places indicated where they have potentially made mistakes. See Gregory Urichs analysis of mass distribution within WTC 1+2 for more information.

I hope this explains how I understand that NISTs report is testable at several levels, but I will refrain from giving suggestions on a course of action until you reply

There likely is no other data available on the construction of the building,

So, NIST just made it up?

I don't believe that NIST made up the construction of the buildings, just that they have likely collected all the available data in order to produce their report, and I doubt that there will be much available information they have missed.

I'm not sure who claims that nano-thermate causes explosive like blasts?

I could not give you specific names, but as I'm sure you're aware the claims of truth movement supporters vary wildly, from LIHOP to claims of nukes used to destroy the towers. My point was simply to illustrate that a wild variety of claims are made and many are quite inconceivable.

You know this as fact? Why have we been persuing these weapons for over 30 years then if they are unpracticle?

I do know this as fact, and 'we', I, you or anyone have not been persuing these weapons. "Directed Energy Beams" do exist, but in the form of things like LASER technology, this technology is used to heat items to failure rather than invoke an unknown physical principle called 'dustification'. I can go into this with more detail, but if you are not familiar with these claims I suggest you read Dr Judy Wood's website where your head may explode

See this is where structural engineering comes into play. When designing, you have to look at all loads and what they do to a structure. This includes live, wind, dead, siesmic etc. loads. Then we design the structure for the maximum of these values. That includes bending, deflection, moment etc. So, when they say a member can withstand something, it means that that something is the ultimate and the other loads produce something less. Hence, if the wind load governs and the wind is not blowing that day, there is more capacity for other loads. Etc, etc.

Indeed, I simply wanted to illustrate that if say a member yields at 100kip, dead loads are 50kip and expected live loads only account for 5kip, one could claim the member has a 20x safety margin for live loads, when in fact the margin is significantly lower for dead loads or combinations of the two.

Yes, I can. Because it wouldn't take an entire structure to show a few columns bending inward from trusses pulling on them. BTW, how much have we spent on the war in Iraq? How many full towers could have been built with that money? So, yes, it's possible.

This is a complex subject, which I am not qualified to make a statement in. I notice you've disputed some of Newtons Bits calculations above, although I don't quite understand your criticism. I don't entirely disagree with your requirements, but I would like to point out that the amount of force imparted should be able to be calculated, and that NIST would have needed to construct the largest fire test facility in the world (as far as I know) in order to fulfil your requirement. I'm assuming that a simulation is not sufficient of course.

I have always said I could be wrong in my convictions. See my signature about absolutes and people thinking they know everything.

Hopefully I will not fall into the same trap, I certainly don't believe I know everything, but I am quite tired of hearing the same old claims, 'free-fall speed' and such.

It is clear your beliefs are relatively 'mainstream' so if you have time I would like to ask what alternative hypotheses you find plausible? There has yet to be a coherent narrative invoking a conspiracy theory that I am aware of, and this is often reflected in the conflicting nature of claims made (for example claiming terrorists were not involved, and then quoting administration officials citing incompetence as the reason the attacks succeeded).

I await your response, while I have to reply to bsbray

I'm just bumping the thread beause for some reason MYATS says that exponent has responded but I can't see the post? Nothing to see here...move along.

Edit: That's better.

[edit on 9/16/2008 by Griff]

Originally posted by exponent
It is clear your beliefs are relatively 'mainstream' so if you have time I would like to ask what alternative hypotheses you find plausible?

It has been less than 10 years since we've proven mathematically that bumble bees can actually fly. I'd rather not speculate on what is "plausible" and what is not. I'd rather talk about things I have knowledge of. Sorry if that's not the answer you were looking for, but I've been trapped by that before. Not that I'm accussing you of such tactics. You're a civil debater and I like that.

It has been seven years since *911.
If we have not yet gotten any different story ffrom the government we will never get one.

reply to post by Griff


I have to wonder why Newton hasn't updated his blog? And also why this thread all of a sudden just died?

Exponent: I'm getting to your last post also. Just have been busy, but finally got 3 projects off my back today.

Originally posted by Griff
I have to wonder why Newton hasn't updated his blog? And also why this thread all of a sudden just died?

Exponent: I'm getting to your last post also. Just have been busy, but finally got 3 projects off my back today.

I lost my reply to the post after yours and it's quite a nice day in the UK today so I haven't really bothered replying. I'm not sure how often Newtons Bit checks here but I'll send him a message if I see him.

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?

Indeed. It would be more appropriate to state that assuming the steel reaches 600C. I am a doer of math, not a technical writer.

[edit on 20-9-2008 by Newtons.Bit]

reply to post by Valhall


I don't know what kind of mickey mouse website that is, but I got my information from AISC: the people who write the spec that is referenced by every American building code. You can find it here: www.aisc.org...

Scroll down to page 9. It is very clear the the reduction in modulus is 0.3 at 600C (or perhaps it 0.31 or so). Until proven otherwise, I'm going to go ahead and assume that AISC is correct.

I think that should answer both yours and Griff's questions. Remember folks, use real resources from actual real sources and you may actually find the truth!

I've also updated my blog post from Feb. It now has a reference to how I got a reduction in modulus of 0.3.

Originally posted by Newtons.Bit
www.aisc.org...

Scroll down to page 9. It is very clear the the reduction in modulus is 0.3 at 600C (or perhaps it 0.31 or so). Until proven otherwise, I'm going to go ahead and assume that AISC is correct.

I think that should answer both yours and Griff's questions. Remember folks, use real resources from actual real sources and you may actually find the truth!

Only in the unconstrained condition does stiffness equal modulus of elasticity. Have you taken this into account? Or are the exterior columns considered unrestrained?

Also, have you taken into account the elongation of the element at 600C? What I mean is that stiffness = AE/L. Your graph shows the stiffness reduction factor. Does it account for the delta L caused by the element heating to 600C? Having a larger L at 600C would give a higher reduction factor for E (modulus of elasticity) at that temperature. Correct?

Maybe not a huge change but, It seems as though it would.

BTW, you say 500C in your blog anyway. But then use the reduction factors for stiffness at 600C? Maybe just a typo?

CALCULATION 2: DIAPHRAGM DAMAGE, 500C FIRE

newtonsbit.blogspot.com...


[edit on 9/20/2008 by Griff]

Originally posted by Griff

Originally posted by Newtons.Bit
www.aisc.org...

Scroll down to page 9. It is very clear the the reduction in modulus is 0.3 at 600C (or perhaps it 0.31 or so). Until proven otherwise, I'm going to go ahead and assume that AISC is correct.

I think that should answer both yours and Griff's questions. Remember folks, use real resources from actual real sources and you may actually find the truth!

Only in the unconstrained condition does stiffness equal modulus of elasticity. Have you taken this into account? Or are the exterior columns considered unrestrained?

Also, have you taken into account the elongation of the element at 600C? What I mean is that stiffness = AE/L. Your graph shows the stiffness reduction factor. Does it account for the delta L caused by the element heating to 600C? Having a larger L at 600C would give a higher reduction factor for E (modulus of elasticity) at that temperature. Correct?

Maybe not a huge change but, It seems as though it would.

BTW, you say 500C in your blog anyway. But then use the reduction factors for stiffness at 600C? Maybe just a typo?

CALCULATION 2: DIAPHRAGM DAMAGE, 500C FIRE

newtonsbit.blogspot.com...


[edit on 9/20/2008 by Griff]

Griff, in almost all cases the stiffness of an element has a linear relationship with the modulus of elasticity. Hence the term linear-elastic, which I'm sure you're familiar with. There are some cases, such as shear-locking in a Timoshenko element, that may produce different effects. However those effects only come into play with short stubby elements, not with an element that has the length to radius of gyration ratio of these columns.

I don't include the effects of an increased L in my calculations. Nor do I assume that the column is restrained (and to a degree it is). Both of these would decrease the temperature in which a column would fail at. An increased L for obvious reasons, and any restraint would just add to the total axial load in the column, thus increasing p-delta effects.

I fixed the typo in my blog post.

Any more questions?

[edit on 20-9-2008 by Newtons.Bit]

How many core columns would have to have huge sections cut completely out like that, to cause an initiation scenario? Or do we have enough data for that?

Originally posted by bsbray11
How many core columns would have to have huge sections cut completely out like that, to cause an initiation scenario? Or do we have enough data for that?

Not many. You can see NIST (1-6D) for how they calculated this force. The WTC was fortunate in that the hat truss at the top of the building redistributed a large portion of the axial load from severed columns. Had it not been there, the towers may have collapsed immediately, and not later from the fires.

Originally posted by Newtons.Bit
Not many.

Believe it or not this actually wasn't the kind of answer I was hoping for.

You can see NIST (1-6D) for how they calculated this force.

I may look it up later but I already know some variables they would have to consider, which is why I asked if enough data is truly present. I would hate to see them making any assumptions that, if incorrect, would change the theoretical outcome. I've seen both the towers' dead weights and design factors disputed, among other things, and honestly there does not appear to a reliable and impartial source to refer to without appealing back to something that the NIST team itself also published.

reply to post by bsbray11


I can't give an exact number, or even an approximate number. The analysis required to determine this is exceedingly complex. I can't do it by hand.

reply to post by Newtons.Bit


So when I ask how many would have to completely fail out of the 47, and you say "not many," what data are you basing that on? I know it has been estimated that only a few out of the 47 could be failed during impact, so it would have to be "not many" or else we would be stuck.

Originally posted by bsbray11
reply to post by Newtons.Bit

 

So when I ask how many would have to completely fail out of the 47, and you say "not many," what data are you basing that on? I know it has been estimated that only a few out of the 47 could be failed during impact, so it would have to be "not many" or else we would be stuck.

The NIST report. Try reading it. They give a pretty detailed analysis of how many columns were likely to fail for a number of different conditions.

Originally posted by Newtons.Bit
The NIST report. Try reading it. They give a pretty detailed analysis of how many columns were likely to fail for a number of different conditions.

Do you mean the original NIST model that states neither the plane impacts or fire casued the collapse?

reply to post by ULTIMA1

Correct. The original NIST model that said it was a combination of the plane impacts, and resulting fires, that started a chain of events that led to eventual collapse.

Originally posted by Newtons.Bit
The NIST report. Try reading it.

This comes immediately after I post this:

...I asked if enough data is truly present. ... [T]here does not appear to a reliable and impartial source to refer to without appealing back to ... NIST

Sorry, but I am coming from the perspective that the NIST report is manipulative, and I need more academic independence in all of this before I feel as comfortable as you do with them.

Are you familiar with Christians using the Bible to prove the Bible?

They give a pretty detailed analysis of how many columns were likely to fail for a number of different conditions.

And you either missed or ignored the part of my post where I ask where all these variables are being supplemented from.