The latest from Dr Quintiere

[cmcaulif]

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.

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.

[leftysergeant]

Is that available on line somewhere? Some people I know of need to see that. They are trying to paint Quintiere as a twoofer.

[Mangoose]

link (http://ascelibrary.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JPCFEV000021000006000414000001&idtype=cvips&prog=normal)

[Norseman]

The abstract is available online here, but you need a subscription to read the full text:
http://ascelibrary.aip.org/dbt/dbt.jsp?KEY=JPCFEV&Volume=CURVOL&Issue=CURISS

[ElMondoHummus]

Is that available on line somewhere? Some people I know of need to see that.


You thinkin' of that Spooked guy of the chickenwire/can-of-kerosene fame? :)

[Gravy]

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]

You thinkin' of that Spooked guy of the chickenwire/can-of-kerosene fame? :)Spooked needs to see a doctor, not a study.

[cmcaulif]

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.

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.

[slyjoe]

Spooked needs to see a doctor, not a study.

I have GOT to remember that one! Pithy too. :)

[T.A.M.]

Spooked needs to see a doctor, not a study.

Forget it, my practice is closed to insane truthers...lol

TAM:)

[Mangoose]

leftysergeant -- You have a PM.

[ElMondoHummus]

Spooked needs to see a doctor, not a study.


He he... can't argue with you there.

[JimBenArm]

Spooked needs to see a doctor, not a study.
Maybe a doctor could use him in a study?

[LashL]

Forget it, my practice is closed to insane truthers...lol

TAM:)

Smart move, TAM :)

[LashL]

Maybe a doctor could use him in a study?

Perhaps as a blunt object.


{As in the old board game called "Clue": Doctor (X) in the Study with a Blunt Object.}

[cmcaulif]

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.

[cmcaulif]

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 (http://wtc.nist.gov/progress_report_june04/appendixj.pdf) 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.

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.

[R.Mackey]

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).

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.

[Apollo20]

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!

[Arus808]

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?

[Apollo20]

The important thing about fuel load is that it mostly affects the duration of a fire. A 20 kg/m^2 fire in the twin towers will only last about 1500 seconds and then its kaput because its run out of fuel. A 40 kg/m^2 combustible load allows the same, approx 2 MW per workstation, fire to burn for 50 minutes. This has important implications for the heating of steel above its critical temperature of 600 deg C. Certainly 20 kg/m^2 fuel load was insufficient to heat columns weighing over 5 tons to this temperature.

[jaydeehess]

The important thing about fuel load is that it mostly affects the duration of a fire. A 20 kg/m^2 fire in the twin towers will only last about 1500 seconds and then its kaput because its run out of fuel. A 40 kg/m^2 combustible load allows the same, approx 2 MW per workstation, fire to burn for 50 minutes. This has important implications for the heating of steel above its critical temperature of 600 deg C. Certainly 20 kg/m^2 fuel load was insufficient to heat columns weighing over 5 tons to this temperature.

Wouldn't the fact that the fire skipped a small-involved-area step of typical office fires aid in speeding the temp rise in the steel not to mention the initial bump in fuel load from the acellerant, the jet fuel?

This fire involved several adjacent floors at once right from the outset. Typically heat from a fire on one floor must be conducted through the ceiling to affect trusses and even if there is a fire on the upper floor its is significantly later and the fuel load on the original fire floor will have burned off to some degree. Such was not the case in the towers. Similarily a fire on one face of a column typically could take time to progress to engulf the coulmn. Such was not the case for some of the columns in the towers. Thousands of gallons of acellerant being tossed about has to make a difference.

ETA: basically the fact that the fire was immediatly a multistorey fire by the use of thousands of gallons of acellerant made the heat transfer to the columns more efficient than it would be in a typical office fire.

[rwguinn]

Wouldn't the fact that the fire skipped a small-involved-area step of typical office fires aid in speeding the temp rise in the steel not to mention the initial bump in fuel load from the acellerant, the jet fuel?

Quite obviously, the fire burned for a bit more than any 1500 seconds--so the NIST estimate was biased toward NON-COLLAPSE, again.
Apollo20, the non-scientific chemist, wants exact numbers, damnit! Whether they exist or not, and whether they are relevant or not.
None of this Enveloping the problem stuff, nosirebob! We must be exact. We must be precise, not accurate:D.

[cmcaulif]

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.

The fuel load estimate, which on a side note may also have implications on the live load, since the estimated furniture weight and total weight was higher than NIST's estimate, was not published(as in published in a journal), it was a report prepared by Ms Stewart privately for Dr. Quintiere, I'm not sure how copyright works in that case.

But anyhow, PM sent.

[cmcaulif]

Quite obviously, the fire burned for a bit more than any 1500 seconds--so the NIST estimate was biased toward NON-COLLAPSE, again.
Apollo20, the non-scientific chemist, wants exact numbers, damnit! Whether they exist or not, and whether they are relevant or not.
None of this Enveloping the problem stuff, nosirebob! We must be exact. We must be precise, not accurate:D.

I'm not sure that biasing the fuel load towards non collapse is really acceptable, especially when there are some fuel sources that simply went unaccounted for, such as storage areas and conference rooms, which will play a part in heating the steel. Of course the numbers wont be exact, and the report wont be exact, but unless you are trying to recreate what was actually going on in the structure there is not much of a point in doing a study like NIST did.

[cmcaulif]

The important thing about fuel load is that it mostly affects the duration of a fire. A 20 kg/m^2 fire in the twin towers will only last about 1500 seconds and then its kaput because its run out of fuel. A 40 kg/m^2 combustible load allows the same, approx 2 MW per workstation, fire to burn for 50 minutes. This has important implications for the heating of steel above its critical temperature of 600 deg C. Certainly 20 kg/m^2 fuel load was insufficient to heat columns weighing over 5 tons to this temperature.

I havent checked your numbers on burnout times, but the WTC fires were traveling fires, with a 'near field' where structural elements were exposed to flame, and a 'far field' which is away from the flame but is still subject to hot gases and soot. The far field can still have very high temperatures, even after all of the combustibles in it have been consumed. More on that from a very interesting paper from Dr. Barbara Lane and some of her associates at Arup Fire:

Rein et all (http://www.era.lib.ed.ac.uk/bitstream/1842/1980/1/Rein_Interflam07.pdf), Multi-Story Fire Analysis for High Rise Buildings, 11th Interflam, London, September 2007 pp 605-616

When a small fire is in the vicinity of a structural element, the temperature corresponds to the near field (in
the order of 1300°C). This heating would last for about 10 min to 20 min for typical office fuel loads (in
the range from 20 to 40 kg/m2) independently of the fire size. As reported before, for the average office
building, a heat released rate per unit area of 500 kW/m2 fire lasts for approximately 14 min to burn. As
the fire travels away from the element, the far field surrounds it and temperatures from 700 °C down to
200 °C are sustained, albeit for a period approximately ten times longer.

[Apollo20]

cmcaulif:

Thanks for starting this interesting thread.

Actually most of the heat released by the WTC fires escaped as SENSIBLE HEAT. It is a simple matter to calculate this and show that heat energy was lost to the combustion gases at a rate of about 300 MW per fire-affected floor, with no more than 25 % of the available heat energy being absorbed by the steel as radiant (infrared) energy. This should not be surprising since large industrial reheating furnaces in steel-works have thermal efficiencies of only about 30 % and these furnaces are DESIGNED to heat steel.

You know, if NIST had a good REASON to use very low fuel loads - say to be very conservative in its calculations - it should have said so. But since it did not, we have to assume that 20 kg/m^2 was NIST's best estimate. I beileve Quintiere is absolutely right-on in criticizing NIST for this!

[Max Photon]

The important thing about fuel load is that it mostly affects the duration of a fire. A 20 kg/m^2 fire in the twin towers will only last about 1500 seconds and then its kaput because its run out of fuel. A 40 kg/m^2 combustible load allows the same, approx 2 MW per workstation, fire to burn for 50 minutes. This has important implications for the heating of steel above its critical temperature of 600 deg C. Certainly 20 kg/m^2 fuel load was insufficient to heat columns weighing over 5 tons to this temperature.




Something's up with the fires:


WTC2's NE corner fire burned like a fireplace with a fake log and a gas feed. It even seemed to have have an On/Off valve.

There were other WTC2 fires seen that - according to NIST - did not follow natural fire progressions.

NIST cites other bizarre phenomena unusual for building fires.


You all should come join Bedtime Stories, with Max Photon (http://forums.randi.org/showthread.php?p=3163411#post3163411), where we all sit around and watch NCSTAR 1-5A/9/C together. This is a NIST-narrated photo slide-show of the exterior of WTC2 from impact to collapse initiation.

NIST tells a very exciting story, and it will serve you well in this discussion and others to have familiarity with the strange zoology of observations.


Max Photon says the fires were deliberately catalyzed.


Max Photon

(The guy who says the fires were deliberately catalyzed.)


* * *

[jaydeehess]

Would I be correct in assuming that storage areas, with a higher fuel load, would be located closer to the core rather than the perimeter? That would have implications as to near feild and far feild that cmcaulif brings up.

Also, on the floors most affected by impact the fuel load is rubblized office contents as well as aircraft debris (in the path of the aircraft) and would be more concentrated along one side of the core in the north tower at least.

[jaydeehess]

Max Photon says the fires were deliberately catalyzed.


Max Photon

(The guy who says the fires were deliberately catalyzed.)

Max Photon is the guy who ignores the large aircraft crashing into the towers and the effect that would have on the burning contents in the towers.

[Alferd_Packer]

Max Photon says the fires were deliberately catalyzed.


Max Photon

(The guy who says the fires were deliberately catalyzed.)


* * *

You keep using that word, but I don't think it means what you think it means.

[Max Photon]

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!


The important thing about fuel load is that it mostly affects the duration of a fire. A 20 kg/m^2 fire in the twin towers will only last about 1500 seconds and then its kaput because its run out of fuel. A 40 kg/m^2 combustible load allows the same, approx 2 MW per workstation, fire to burn for 50 minutes. This has important implications for the heating of steel above its critical temperature of 600 deg C. Certainly 20 kg/m^2 fuel load was insufficient to heat columns weighing over 5 tons to this temperature.


cmcaulif:

Thanks for starting this interesting thread.

Actually most of the heat released by the WTC fires escaped as SENSIBLE HEAT. It is a simple matter to calculate this and show that heat energy was lost to the combustion gases at a rate of about 300 MW per fire-affected floor, with no more than 25 % of the available heat energy being absorbed by the steel as radiant (infrared) energy. This should not be surprising since large industrial reheating furnaces in steel-works have thermal efficiencies of only about 30 % and these furnaces are DESIGNED to heat steel.

You know, if NIST had a good REASON to use very low fuel loads - say to be very conservative in its calculations - it should have said so. But since it did not, we have to assume that 20 kg/m^2 was NIST's best estimate. I beileve Quintiere is absolutely right-on in criticizing NIST for this!



Why does NIST have 4-5 psf fuel loads for WTCs 1 & 2, when 13-18 psf is expected?


If we view this through Paul's Magic Filter, which disambiguates the NIST reports using the constraint that the need for plausible deniability means the NIST reports do not lie, but rather, tell then ambiguated truth, then perhaps we can solve this mystery.

NIST is telling the truth that the office fuel loads - on the specific floors in question - were indeed 4-5 psf.

And it is true that 3-4 times NIST's fuel load is expected.


Here is the trick:

The difference between expected and NIST's number is the amount of supplementary catalyst used!

Get it?

By quoting a low fuel load, approximately the equivalent of 10 psf of supplementary catalyst could be cloaked by the difference!


Note that the catalyst - if care is exercised - can be made to heat the steel much more efficiently than a typical office fire. (For example, catalyst inside a box column will heat the steel very efficiently.)


Using this trick, plausible deniability has been successfully engineered.

However, it leaves the evidence hiding in plain view.


Max

* * *

[Dave Rogers]

Why does NIST have 4-5 psf fuel loads for WTCs 1 & 2, when 13-18 psf is expected?


If we view this through Paul's Magic Filter, which disambiguates the NIST reports using the constraint that the need for plausible deniability means the NIST reports do not lie, but rather, tell then ambiguated truth, then perhaps we can solve this mystery.

NIST is telling the truth that the office fuel loads - on the specific floors in question - were indeed 4-5 psf.

And it is true that 3-4 times NIST's fuel load is expected.


Here is the trick:

The difference between expected and NIST's number is the amount of supplementary catalyst used!


You slipped up at your own game, Max. If you're right, then the amount of catalyst present was negative. NIST's numbers were smaller than the expected loads.

Nice try, though.

Dave

[Apollo20]

Dave Rogers:

I think Max's point is that a fuel load of 4-5 psf cannot explain the intensity of the observed fires in WTC 1 & 2, and I have to agree. Now, of course, that doesn't mean thermite was used, only that NIST's estimated fuel load is very strange.

jaydeehess:

What would the combustibles be in the core areas? Do you have any information on this? Surely the core of each tower was dominated by elevator shafts, hallways and stairwells. Once the spilled jet fuel burned off, what was left to burn in the cores?

[jaydeehess]

jaydeehess:

What would the combustibles be in the core areas? Do you have any information on this? Surely the core of each tower was dominated by elevator shafts, hallways and stairwells. Once the spilled jet fuel burned off, what was left to burn in the cores?

I am referring to the north tower specifically.

When the plane hit , it would have pushed the office furnishings into the core area on the floors where the fuselage impacted. The rubble that would have hit the core columns and piled up there included much of the aircraft debris.

So you end up with a longer burning fire within the core area if you assume that the debris contained most of the office furnishings from the office space between core and windows has now been concentrated in a smaller area in addition to aircraft debris that ended up there as well.


The famous photo of the woman in the impact hole shows that not much was left in the immediate area of the perimeter impact as the fire at that spot burned out fairly soon (which had little effect on fire weakening since it is at this part of the building that there were a lot of severed perimeter columns due to the impact itself). That is, there was little fire at the perimeter where the plane hit even if there was a much greater fire about 100 feet from the impact hole, at the core. That woman would be 100 feet, upwind, from a large fire. It would also explain why she is where she is. With a fire raging at the core she cannot get off that floor, and the coolest spot with fresh air would have been at the impact hole.

[Apollo20]

jaydeehess:

Very interesting suggestion!

I think NIST do mention aircraft debris as a fuel source but I havn't seen much specific(s).

Seat cushions, upholstery, blankets, carpeting, ceiling and floor panels, etc, would add up to at least 5 tonnes of combustibles per aircraft, but this is small compared to the total fuel load from offices per floor.

However, the aircraft aluminum alloy is another story; but on that one NIST has apparently closed the book.....

Or perhaps, has never opened it!

[Max Photon]

jaydeehess:

Very interesting suggestion!

I think NIST do mention aircraft debris as a fuel source but I havn't seen much specific(s).

Seat cushions, upholstery, blankets, carpeting, ceiling and floor panels, etc, would add up to at least 5 tonnes of combustibles per aircraft, but this is small compared to the total fuel load from offices per floor.

However, the aircraft aluminum alloy is another story; but on that one NIST has apparently closed the book.....

Or perhaps, has never opened it!

[bold mine]





This is an incredibly important point! No one thinks of the potential energy of the aluminum.


MAX-MIHOP says that the emotionally-potent oversimplification of "jets laden with jet fuel" actually serves to cloak the more complex reality - that the jets' aluminum carried enormous exploitable potential energy.

No one says, "the jets laden with aluminum."

(Remember, and aluminum/water/(hydrogen) explosion - for a given weight of aluminum - has a greater yield than an explosion from the same weight of TNT.)

Jet fuel cloaks aluminum, as cutting steel cloaks heat-weakening steel.


Max

* * *

[jaydeehess]

jaydeehess:

Very interesting suggestion!

I think NIST do mention aircraft debris as a fuel source but I havn't seen much specific(s).

Seat cushions, upholstery, blankets, carpeting, ceiling and floor panels, etc, would add up to at least 5 tonnes of combustibles per aircraft, but this is small compared to the total fuel load from offices per floor.

However, the aircraft aluminum alloy is another story; but on that one NIST has apparently closed the book.....

Or perhaps, has never opened it!

How well does hydralic fluid burn? There's not much there but it would also be considered an acellerant given that it would spread out over a large area.

Then there is the issue of oxygen generators which could create a great deal hotter fire for a short time in very localized areas within the general fire zone.

Its not so much the total combustables that I see as the problem either, at least not for the north tower. Its the concentration of those combustables from one side of the tower into the core area on at least two floors. As you said the core columns would normally not be surrounded by much in the way of combustible material. In the north tower some of those core columns would have been. In the south tower it would be at the far side from the impact where the 'molten metal' is seen dripping from the corner fire.

As far as the jet fuel goes, again it is not so much that it adds to the fuel load but that it ensures that there is a major fire on adjacent floors immediatly as opposed to the typical progression of an office fire. Heat input to the columns would have the efficiency (perhaps not the correct wording....) of a multi level fire right from the outset.

As for the aluminum alloy, videos of air crashs such as the one in Toronto last year or the year before where it skidded off the end of the runway and caught fire, illustrate quite well that the aluminum does get consumed in those fires. The plane in T.O. was intact when it came to rest and caught fire, but by the time the fire was out much of the cabin was burned away.
So it would seem that one must allow for the aluminum to also be considered fuel load. I would think that its rubblized condition and mixing with the other fuel in the tower would aid in its being involved in the fire as well

[jaydeehess]

MAX-MIHOP says that the emotionally-potent oversimplification of "jets laden with jet fuel"

an emotional oversimplification much used by the CT crowd in which they attempt to say that the OT has the towers collapsing because the jet fuel fires weakened the steel.

In fact the jet fuel served not so much to cause the weaking but as an acellerant that had this office fire completely skip the typical step of one small point of origin and go straight to , large involved area on several floors step.

One thing is very very sure about the fire in the towers. It resembles a typical office fire only because there is stuff burning and smoke being created. Beyond that it is rather unique.

[Max Photon]

an emotional oversimplification much used by the CT crowd in which they attempt to say that the OT has the towers collapsing because the jet fuel fires weakened the steel.


That is a very good example.




In fact the jet fuel served not so much to cause the weaking but as an acellerant that had this office fire completely skip the typical step of one small point of origin and go straight to , large involved area on several floors step.


That's is true for WTC1.

WTC2 has mostly stationary, localized fires.


One thing is very very sure about the fire in the towers. It resembles a typical office fire only because there is stuff burning and smoke being created. Beyond that it is rather unique.


...what, with the:

flashes that look like thermite fuse
coordinated smoke puffs reminiscent of old-fashioned steam-driven pipe organs
numerous major smoke releases - all 1 minute long, +/- a few seconds
pressure pulses
debris ejected at high speeds
falling debris
bright white glows
sequential metal flows
fires that suddenly appear and disappear
a 10 minute metal fire at Column 301/81st bolt-access-holes
hanging objects seen through open windows that change their positions
hanging objects seen through open windows that disappear and reappear.
Column 301/81 bowing inward and failing, initiating the collapse of WTC2
AND THAT ALL OF THE ABOVE ARE CORRELATED!

Unique indeed.


Max

(so were the fires)

* * *

[Peephole]

Another one for the list:
http://911science.googlepages.com/

[Disbelief]

How well does hydralic fluid burn? There's not much there but it would also be considered an acellerant given that it would spread out over a large area.



Hydraulic fluid burns well, and there would be a pretty good amount for the landing gear and struts. Someone who works on jets would probably be able to tell you the normal amount.

[jaydeehess]

Thanks disbelief,
I meant "not much" as a relative measure. If one poured it out on your kitchen floor it would be an enormous amount of fluid. If one compares it to the Jet fuel in the aircraft it is small and if one compares it to the total combustibles on one floor of the WTC towers it is even smaller.

However as an acellerant to hasten the ignition of those combustibles it gains a great deal more significance.

[cmcaulif]

cmcaulif:

Thanks for starting this interesting thread.

Actually most of the heat released by the WTC fires escaped as SENSIBLE HEAT. It is a simple matter to calculate this and show that heat energy was lost to the combustion gases at a rate of about 300 MW per fire-affected floor, with no more than 25 % of the available heat energy being absorbed by the steel as radiant (infrared) energy. This should not be surprising since large industrial reheating furnaces in steel-works have thermal efficiencies of only about 30 % and these furnaces are DESIGNED to heat steel.

This is a big factor, but I was merely referring to the time that the steel will be exposed to high temperatures, which will be much longer than your first post would imply, due to the fact that the fires were 'traveling fires'

You know, if NIST had a good REASON to use very low fuel loads - say to be very conservative in its calculations - it should have said so. But since it did not, we have to assume that 20 kg/m^2 was NIST's best estimate. I beileve Quintiere is absolutely right-on in criticizing NIST for this!

I agree, a per workstation estimate seems like it will have a great deal of uncertainty, but the storage and conference rooms should be considered at the very least.

[cmcaulif]

Would I be correct in assuming that storage areas, with a higher fuel load, would be located closer to the core rather than the perimeter? That would have implications as to near feild and far feild that cmcaulif brings up.

Also, on the floors most affected by impact the fuel load is rubblized office contents as well as aircraft debris (in the path of the aircraft) and would be more concentrated along one side of the core in the north tower at least.

It would make sense to assume the storage was in the office area closer to the core, but I'm not sure if that is where it actually was. They used an the architectural drawing from the March & Mc Clennan floors to do their survey, but had to return them when they were finished.

From what I have read it looks like the trusses are definitely the key to the collapses, but NIST suggests that the core played a big role too. I also think that while Quintiere makes a good case for inadequate fireproofing, he does not make a good case for collapse because when a truss 'walks off' its truss seat it does not fall down, that is just the point when pull in becomes large.

[cmcaulif]

Another one for the list:
http://911science.googlepages.com/

Here are a bunch more papers on the WTC for your biblio if you like...

Journal Papers

John K. McGee et al, “Chemical Analysis of World Trade Center Fine Particulate Matter for Use in
Toxicologic Assessment”, Environmental Health Perspective (June 2003)

UC Davis Aerosol Study: Cahill et al., “Analysis of Aerosols from the World Trade Center
Collapse Site, New York, October 2 to October 30, 2001”, Aerosol Science and Technology,

Lioy et al, “Characterization of the Dust/Smoke Aerosol that Settled East of the World Trade Center
(WTC) in Lower Manhattan after the Collapse of the WTC 11 September 2001”, Environmental Health
Perspectives, Volume 110 #7

Use of High-Efficiency Energy Absorbing Device to Arrest Progressive Collapse of Tall Building Qing Zhou and T. X. Yu Journal of Engineering Mechanics 130, 1177 (2004)

The Structural Steel of the World Trade Center Towers. Gayle, Frank W.; Banovic, Stephen W.; Foecke, Tim. Advanced Materials & Processes v. 162 no10 (October 2004) p. 37-9

Coupled fire dynamics and thermal response of complex building structures
Proceedings of the Combustion Institute, Volume 30, Issue 2, January 2005, Pages 2255-2262 Kuldeep Prasad and Howard R. Baum

Burgess, I.W., 'Fire Resistance of Framed Buildings', Physics Education, 37 (5), (2002) pp390-399.

G. Flint, A.S. Usmani, S. Lamont, J. Torero and B. Lane, Effect of fire on composite long span truss floor systems, Journal of Constructional Steel Research 62 (4) (2006), pp. 303–315.

conference papers

Abboud, N., M. Levy, D. Tennant, J. Mould, H. Levine, S. King, C. Ekwueme, A. Jain, G. Hart. (2003) Anatomy of a Disaster: A Structural Investigation of the World Trade Center Collapses. In: Proceedings of the Third Congress on Forensic Engineering. San Diego: American Society of Civil Engineers. pp 360-370

Beyler, C., D. White, M. Peatross, J. Trellis, S. Li, A. Luers, D. Hopkins. (2003) Analysis of the Thermal Exposure in the Impact Areas of the World Trade Center Terrorist Attacks. In: Proceedings of the Third Congress on Forensic Engineering. San Diego: American Society of Civil Engineers. pp 371-382

Thater, G. G.; Panariello, G. F.; Cuoco, D. A. (2003) World Trade Center Disaster: Damage/Debris Assessment In: Proceedings of the Third Congress on Forensic Engineering. San Diego: American Society of Civil Engineers. pp 383-392

Choi (http://fire-research.group.shef.ac.uk/Downloads/SC_Baltimore.pdf), S.K., Burgess, I.W. and Plank, R.J., 'The Behaviour of Lightweight Composite Floor Trusses in Fire', ASCE Specialty Conference: Designing Structures for Fire, Baltimore, (Oct 2003) pp 24-32.

Jowsey (http://www.era.lib.ed.ac.uk/bitstream/1842/886/1/326_Jowsey.pdf) et all, Determination of Fire Induced Collapse Mechanisms in Steel Framed Structures, 4th European Conference on Steel and Composite Structures, 10 June 05, 69-76

Usmani (http://www.era.lib.ed.ac.uk/bitstream/1842/1561/1/Usmani+SiF+06.pdf) et all, Collapse scenarios of WTC 1 & 2 with extension to generic tall buildings, Oct-2006 Proceedings of the International Congress on Fire Safety in Tall Buildings

[gumboot]

For what it's worth, the NIST fuel load calculation was based on readily available fuel for initial burn - that is things like paper lying on desks. They didn't, for example, include paper filed away in cupboards or drawers.

My understanding was they were calculating the immediate fuel load capable of being ignited by jet fuel. Once the fire was established all sorts of additional materials would burn, which would not naturally burn if just exposed to a small amount of flame.

An example would be a car fire. There's very little in a car that will quickly and easily combust, but once a fire is established virtually everything in it will burn.

Regarding this scale experiment... how are the characteristics of fire and heat transfer affected by scaling? It would seem to me, since doubling linear scale would increase volume by a factor of eight, that this would have a significant impact.

-Gumboot

[cmcaulif]

For what it's worth, the NIST fuel load calculation was based on readily available fuel for initial burn - that is things like paper lying on desks. They didn't, for example, include paper filed away in cupboards or drawers.

My understanding was they were calculating the immediate fuel load capable of being ignited by jet fuel. Once the fire was established all sorts of additional materials would burn, which would not naturally burn if just exposed to a small amount of flame.

An example would be a car fire. There's very little in a car that will quickly and easily combust, but once a fire is established virtually everything in it will burn.

If that is the case, I'm not sure why NIST would do that, the fires lasted much longer after the initial ignition period.

Regarding this scale experiment... how are the characteristics of fire and heat transfer affected by scaling? It would seem to me, since doubling linear scale would increase volume by a factor of eight, that this would have a significant impact.

-Gumboot

He gives a brief discussion of the dimensional analysis that had to be performed for this study in the ASCE paper, but a full treatment can be found here:

Scaling Applications in Fire Research (http://www.fire.nist.gov/bfrlpubs/fire89/art008.html). Quintiere, J. G.
International Symposium on Scale Modeling. July 18-22, 1988, Tokyo, Japan, 12 pp, 1989. Fire Safety Journal, Vol. 15, No. 1, 3-29, 1989.

I have not yet finished my study of this paper(Hopefully I'll be able to give a better answer when I do), but equation 33 relates the length scale to the flow of chemical energy. So far it appears like the scaling laws are very complicated, but as long as they are followed the study is legit.

[Apollo20]

The fuel loads and section factors for steel trusses as compared to steel columns suggest that unprotected trusses could have been heated above the critical temperature of steel, (say T ~ 600 C), in less than 15 minutes while the core columns, due to their great thermal inertia, probably never got above 500 C.

So why did the cores fail?

It was certainly NOT from over-heating of core columns.

Even NIST admit in NCSTAR 1-5 that "fuel loading in the core areas of the focus floors was negligible."

[Gravy]

NIST did include the paper in cabinets in their combustible load estimates, but discounted the paper in metal cabinets according to an industry formula: it was assumed that in undamaged cabinets the paper would burn well after the other workstation contents and wouldn't contribute greatly to the peak heat release rate.

Some of their workstation fire tests were of "rubbleized" workstations, with the paper strewn about and mixed in, but these are less combustible because of limited oxygen in the rubble pile and the presence of wallboard and ceiling tile rubble.

[beachnut]

The fuel loads and section factors for steel trusses as compared to steel columns suggest that unprotected trusses could have been heated above the critical temperature of steel, (say T ~ 600 C), in less than 15 minutes while the core columns, due to their great thermal inertia, probably never got above 500 C.

So why did the cores fail?

It was certainly NOT from over-heating of core columns.

Even NIST admit in NCSTAR 1-5 that "fuel loading in the core areas of the focus floors was negligible."
I see no sources on the first Paragraph at all. Do you just make this up? I wonder if you need the core to fail to have global collapse. Gee, since the core does not handle lateral loads, I wonder if the floors failing made the core fail. Or was it some exotic chemical reaction most of us call fire?

Will the morons of thermite interpret your PhD "veiled bone" as ammo for their madness.

Where does turkey fit in to this?

[cmcaulif]

The fuel loads and section factors for steel trusses as compared to steel columns suggest that unprotected trusses could have been heated above the critical temperature of steel, (say T ~ 600 C), in less than 15 minutes while the core columns, due to their great thermal inertia, probably never got above 500 C.

So why did the cores fail?

It was certainly NOT from over-heating of core columns.

Even NIST admit in NCSTAR 1-5 that "fuel loading in the core areas of the focus floors was negligible."

I think most of the core actually failed after the perimeter failed, and much of the core will have failed due to the tipping motion of the upper block after collapse initiation.

Although the difference in the impact damage patterns to the two buildings lead to a more severe redistribution of the axial loads after impact in WTC2 compared to one. The differences in collapse time lead me to believe that the core damage was an influential factor in the collapse, and not just from impact, but possibly heat weakening as well. While the fuel load within the actual core is probably negligible, being stairs, elevators, etc, there would be combustibles in the office area near it that could heat and weaken it. Even if the core columns dont get all the way to 600C, they are already taking more load than usual, from the post impact load redistributions, and I believe approx 450C is where creep starts to kick in. In short, the core weakening compromises the buildings load redistribution capacity, which has an effect on stability, even though the behavior of the trusses in the fire is likely the largest factor in the collapse.

[jaydeehess]

The fuel loads and section factors for steel trusses as compared to steel columns suggest that unprotected trusses could have been heated above the critical temperature of steel, (say T ~ 600 C), in less than 15 minutes while the core columns, due to their great thermal inertia, probably never got above 500 C.

So why did the cores fail?

It was certainly NOT from over-heating of core columns.

Even NIST admit in NCSTAR 1-5 that "fuel loading in the core areas of the focus floors was negligible."


Call it 450 C (a conservative 10% less than your estimate). You already know the floors are sagging and pulling the perimeter and core towards each other. Enough to cause the perimeter columns to bow inward. The core columns would be heated more than the perimeter columns would they not? So what would the relative strength be between core and perimeter columns? The core columns are laterally braced to each other but those beams are also hot (pulling numbers from a dark place call them 200 C)and expanding, even if only a little, and contributing to the outward pressure on the core columns.

If the cooler but smaller and more numerous perimeter columns bowed
, would the hotter, heavier core bow outward by some amount? If so then you have a situation in which you have core columns with more load than normal (missing perimeter and core columns due to impact , and bowing of perimeter transfering more load to core via the hat truss) AND weakened core columns which now have a geometric problem, they are not bearing their load strictly axially.

Once the perimeter pulls in enough and/or the core columns shift enough the load exceeds the ability of the structure(as a system) to hold together.

[Max Photon]

The fuel loads and section factors for steel trusses as compared to steel columns suggest that unprotected trusses could have been heated above the critical temperature of steel, (say T ~ 600 C), in less than 15 minutes while the core columns, due to their great thermal inertia, probably never got above 500 C.

So why did the cores fail?

It was certainly NOT from over-heating of core columns.

Even NIST admit in NCSTAR 1-5 that "fuel loading in the core areas of the focus floors was negligible."



As I have quoted from NIST elsewhere:

"All steels lose strength with increasing temperature. By 600 °C, most structural steels have lost more than half their strength. At intermediate temperatures the strength is independent of time, but above 500 °C, creep, or time-dependent deformation, further reduces the load-carrying capability."


It is important to remember that the critical temperature of steel (usually less than 600C) is a bit of a misnomer because the critical temperature is not at some critical point of steel, but rather at an arbitrary point of tidy engineers.

In stark contrast, 500C does represent a critical point in steel - a critical point very important to WTC collapse research.

Above 500C, time-dependent deformation - or creep - can manifest (in addition to the loss of strength from heating).


So remember:

600C is not a critical point of steel, but an arbitrary number;
500C is a critical point of steel, above which creep is possible.


Also, remember, time-dependent deformation - or visco-elastic creep - is a key to MAX-MIHOP:

Thermite in box columns heated the columns.
Thermite at gusset seats caused the visco-elastic dampers to burn, which caused the floors to sag.
Sagging floors pulled on perimeter columns.
The pull on the heated columns caused viscoelastic creep.
The columns bowed inward, and failed, thereby initiating collapse.

I'm telling you, that is a much more sensible model than one which has heated floor trusses pulling columns inward. Wouldn't heated trusses expand, and push columns outward?

MAX-MIHOP has columns pulled inward, without first having to push them outward.


As usual, stick with Max Photon-brand everything, and you'll be happier.


Max Photon-brand Max Photon

* * *

[PhantomWolf]

I think most of the core actually failed after the perimeter failed, and much of the core will have failed due to the tipping motion of the upper block after collapse initiation.

I'd suspect this is heading the right way. The core wasn't designed to handle lateral loading, that was the perimiter columns job. Once they had failed, the movement of the upper section would have been applying lateral loads to the core it just couldn't handle.

[tfk]

Did anyone ever find an online version of the Ming Paper:

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

I'd love to read it.

tom

[ElMondoHummus]

Did anyone ever find an online version of the Ming Paper:

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

I'd love to read it.

tom

I work at a university. I'm seeing if our main library can get a hold of it. I'll let you know what I find. It might take a while, though; I definitely do not expect to be contacted back in as little as a day or two (in fact, I put an expiration of one month on the request).

If they have it, and if I can get it cheap, I'll let you know.

[Evilgiraffe]

Did anyone ever find an online version of the Ming Paper:

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

I'd love to read it.

tom

Check your PM's

[tfk]

Elmondo,

Thank you also. I was able to find a copy.

Really, I appreciate your taking the trouble to do that.

tom