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The latest from Dr Quintiere

cmcaulif

Critical Thinker
cmcaulif
Joined
Jul 9, 2007
Messages
405
Its actually a scale model that is refreshingly scientific:

Ming Wang, Peter Chang, James Quintiere, and Andre Marshall "Scale Modeling of the 96th Floor of World Trade Center Tower 1" Journal of Performance of Constructed Facilities Volume 21, Issue 6, pp. 414-421

Abstract: This paper presents an experimental investigation of the World Trade Center Tower 1 (WTC1) collapse using a 1/20-scale model. The WTC1 fire on the 96th floor is reconstructed on a small scale, and structural members including the floor trusses and the exterior wall subsystem are built and tested under scaled fire load. Scaling rules are used to determine the values of the insulating material on the structural systems. This experimental study demonstrates the use of scaled models to investigate a real-world fire disaster. Results from the experimental investigation are compared to analytical results and visual evidence compiled in the National Institute of Standards and Technology report on the investigation of the collapse of WTC towers. This study helps engineers and researchers better understand the fire behavior and the associated structural response in WTC1, and a more solidly grounded collapse hypothesis can therefore pursued.
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There is impact damage to the model's floor, which allows for more ventilation, but one key difference between the NIST simulations and this scale model is the combustible fuel load. For WTC 1, NIST used 20 kg/m2 for the base case and 25 kg/m2. This study takes the fuel load for the 96th floor to be 50 kg/m2, which is justified by a sourced analysis performed for Dr. Quintiere, though I haven't tracked down a copy yet. The trusses are fully fireproofed, yet reach temperatures much higher than NIST predicted a fireproofed truss would reach.

Observations of the model and the WTC fire progression seem to match quite well, however he concludes that his scale model predicts collapse at 102 minutes, matching the observed time to collapse initiation. NIST is cited as having said that three trusses must become disconnected for instability to occur, and at 730 C the trusses will fall off their seats, which would mean that his model agrees with the collapse initiation times. Although, I believe NIST had said that 730 C was the point where a truss would 'walk' off its seat, but not become disconnected, thus allowing the pull in action to become large.
 
Is that available on line somewhere? Some people I know of need to see that. They are trying to paint Quintiere as a twoofer.
 
Quintiere's long been an advocate of full-floor modeling, so it's good to see that he took the bull by the horns here. He's also long claimed that NIST greatly underestimated tower fuel loads, but I haven't seen the study on which he based that claim.
 
Gravy said:
Quintiere's long been an advocate of full-floor modeling, so it's good to see that he took the bull by the horns here. He's also long claimed that NIST greatly underestimated tower fuel loads, but I haven't seen the study on which he based that claim.
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Here is the source he references, I still can't find a copy, I think I will email him.

Stewart, K. 2005. “Analysis of the fuel load calculations for the 96th
floor of the WTC North Tower: Private discussion and report for Dr. J.
G. Quintiere.” Dept. of Fire Protection Engineering, Univ. of Maryland,
College Park, Md.

his reasoning seems to be that 20 is the minimum, while in storage areas, the number can get up to 60. 50 was taken based on a survey of the floor and since '170 four-drawer lateral files should be included'

Its hard to really evaluate that without the Stewart report though.
 
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Does anyone who has read the article have any comments? Even though a subscription is required it might be worth heading down to a local Uni to check it out, the journal is an American Society of Civil Engineers publication, which is usually easy to find.

I'm perusing some of his references and trying to find out about some of the error associated with this type of modeling, however error would seem completely irrelevant given the fact NIST predicts max temps for fireproofed trusses in WTC 1 at not much more than 400oC while Quintiere's model predicts truss temps at 800oC at the time of collapse. This definitely lends credence to the arguement that the fireproofing was not adequate, but it seems the discrepancy in numbers from NIST and Dr. Q boils down to their different fuel load estimates.
 
I have emailed Dr. Quintiere on his fuel load study and he sent me a copy. I can send a copy to someone if you like, or perhaps Gravy or someone else with a site could get in touch with him and get permission to host the document(I don't there is no copyright but that just seems like the way to go).

They compare their results with appendix J of the NIST preliminary report, which gives an estimate for the fuel loading. NCSTAR1-5 also describes how NIST came to their fuel load estimate as well if I'm remembering right.

A big difference between the two is this:

NIST used a per desk weight rather than obtaining combustibles for the
entire floor and attributing that to their experiments. However, in the
impact zone, there are two conference rooms (~1,590 lbs (721 kg) of
combustible materials), 8 sets of four drawer lateral files (48 cabinets=192
drawers~13,824 lbs (6270.5 kg) (of paper that was likely dislodged by the
impact) and the paper storage area (~28,000 lbs (12,701 kg) of paper &
paper/office products) that directly contribute to the initial fire started by
the jet fuel.
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that alone would bump up the fuel load considerably in the office area. The rest of the differences come from differences in the estimated paper weights(largely from above, and from estimated work station contents) and from furniture weights.
 
cmcaulif said:
I have emailed Dr. Quintiere on his fuel load study and he sent me a copy. I can send a copy to someone if you like, or perhaps Gravy or someone else with a site could get in touch with him and get permission to host the document(I don't there is no copyright but that just seems like the way to go).
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If it's published, there will be a copyright...

I'd be interested to read it, if you can toss it over easily -- drop me a PM. Scale models of complex phenomena are always interesting papers. It's not an easy thing to do.
 
NIST really cannot justify the fuel loads it uses for the WTC...

Why do I say that?

I have read Report No: NIST-GCR-96-697. "A survey of fuel loads in contemporaty office buildings" a detailed study of this topic published in 1996 and written under the auspices of............., you guessed it,....NIST!!!

And what does NIST-GCR-96-697 suggest that typical office fuel loads might be? (Remember for the WTC NIST use 4 or 5 psf)... Well 13 to 14 psf!

But it gets better!

I have also read NIST SP-1021, which is about the Cook County Office fire of October 2003. Here we read on page 75 that a typical office has a fuel load of 18 psf.

So who is NIST trying to kid with its 4-5 psf fuel loads for WTC 1 & 2?

And why?

I smell a rat!
 
I dont know apollo, but what htey are guessins is the THEIR BEST guess . NO one knows the exact amount of combustibles on the floors that were hit by the planes, as that is something that will remain a variable.

Dont you think that NIST is basing their estimates on the best possible scenario? Taking the square footage of the floors; the average size of what an office would be in teh buidings based on the available floor plans? The average amount of combustibles found on a floor of an office building.

Seriously, this is nothing more than picking at minor details here. We know that even in a nearly "empty" office, the materials that served as fuel, within is hot enough to cause weakening of the steel supports.

I dont see how this has anything to do with the RESULTS. So what if NIST used a different amount than Quinterre did?

This is like arguing about how many dimples an orange has on its skin. Does the amount of dimples determine that its an orange or not?
 
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