A question for DU engineers concerning thermodynamics,

[hack89]

Aerial survey of Ground Zero showed surface hot spots of 500 -700 degrees C 12 days after the WTC collapse.

1. Is it possible to determine how hot the heat source under the rubble might be?

2. Would the rubble act to increase or decrease the temperature inside the rubble pile.

Thanks.

[sniffa]

1. i'm going to Lie here...

and say i'm not an engineer. :dunce:

[evlbstrd]

2. I'm going to lie, too.

I'm an engineer.

[Dr.Phool]

6. I used to be an Engineer

But, the kind that drove a train.

[NorCalDem]

3. It would be possible to determine all of this information

if the rubble had been studied as evidence, not disposed of as rubble. There are some very interesting reports (some technical) here:
http://www.911research.wtc7.net/index.html

I don't recall where I've seen other engineering reports, and I don't know enough to do any calculations myself. You would need computer simulations and a team of engineers to do the study justice.

[HysteryDiagnosis]

4. Engineering question.... .sort of..... why, after either only 10,000

years... or millions of years, whichever you prefer... is the earth still hot, so hot that it is molten at the core? If you say pressure causes heat... and that the mere gravity of the situation is causing enough pressure to create this heat.... are you not getting something for nothing?? (Two questions there... probably answered easily by someone with background in thermodynamics) This has always puzzled me to no end.

[kevsand]

8. The heat has never been released?

Because there is no effective means for it to dissipate? And therefore the energy has been conserved? Just a guess.

[NorCalDem]

12. Not a master in planetary physics, etc.

Eventually, like the planets in our solar system that are farther from the sun, our planet will grow cold and die out. Even after millions/billions of years, we're still milking the energy stored in our planet since it's birth. If we're not consumed by the sun first, we will fizzle out eventually.

Also, you can never get something for nothing, energy is always decreasing and entropy (measure of disorder in the universe) is always increasing.

[Griffy]

42. energy is neither created nor destroyed.. not decreasing...

entropy work to reduce the order, or complexity over all (such as complex carbon molecules.... i.e you and me... break down to simpler elements) ... so energy goes from form to form.. like mechanical energy does some work, but some is converted to heat.

[kurtyboy]

19. Radioactivity produces nearly as much heat as dissapates

http://www.earthsky.com/scienceqs/lqshows.php?t=20020719

DB: Earth's core temperature is estimated at around 5,000 to 7,000 degrees Celsius. That's about as hot as the surface of the sun -- but vastly cooler than the sun's interior. Earth's core is cooling, but slowly. Over the past three billion years, it might have cooled a couple of hundred degrees.

JB: Earth is close to a steady temperature state -- because it's producing, through radioactive decay, almost as much heat as it's losing. That's our show -- if you have an Earth or sky question, we hope you'll visit our website at earthsky.org. Special thanks today to the National Science Foundation -- and to the Friends of Earth and Sky -- on the web at earthandskyfriends.org. We're Block and Byrd for Earth and Sky.

There's a whole lotta uranium and radium and other radioactive elements down there....

http://www.physlink.com/News/121103PotassiumCore.cfm


Earth's core. Image by NASA.

Radioactive potassium, common enough on Earth to make potassium-rich bananas one of the "hottest" foods around, appears also to be a substantial source of heat in the Earth's core, according to recent experiments by University of California, Berkeley, geophysicists.
Radioactive potassium, uranium and thorium are thought to be the three main sources of heat in the Earth's interior, aside from that generated by the formation of the planet. Together, the heat keeps the mantle actively churning and the core generating a protective magnetic field.

But geophysicists have found much less potassium in the Earth's crust and mantle than would be expected based on the composition of rocky meteors that supposedly formed the Earth. If, as some have proposed, the missing potassium resides in the Earth's iron core, how did an element as light as potassium get there, especially since iron and potassium don't mix?

Kanani Lee, who recently earned her Ph.D. from UC Berkeley, and UC Berkeley professor of earth and planetary science Raymond Jeanloz have discovered a possible answer. They've shown that at the high pressures and temperatures in the Earth's interior, potassium can form an alloy with iron never before observed. During the planet's formation, this potassium-iron alloy could have sunk to the core, depleting potassium in the overlying mantle and crust and providing a radioactive potassium heat source in addition to that supplied by uranium and thorium in the core.

[JackRiddler]

69. depending on the theory...

After the initial accumulation of a molten mass the earth has been cooling slowly in a process that takes billions of years, producing a solid outer crust. The earth continues to generate heat internally from radiation released by its own radioactive matter. At least, that's how I remember it. (I'm not an engineer or a physicist, but read plenty of astronomy, and I'm not lying.)

[Selatius]

5. Well, it's too late now. The evidence was carted off

It's also funny the cockpit voice recorders (the black boxes) weren't recovered at the WTC but it was recovered in Pennsylvania.

[RUMMYisFROSTED]

7. Clearly.

[T Town Jake]

9. ...

1. Yes.

2. Oxygen.

2(a). Oxygen.

2(b). Oxygen.

2(c). Oxygen.

2(d). Oxygen.

...and..

since I know you're going to ask this :tinfoilhat: question again in a slightly different way, I give you:

3. Oxygen.

"Temperature" is a function of combustion, and combustion is a function of the availability of oxygen. At least on this planet.

[NorCalDem]

13. You're dead on TTJ

Most/All of the engineering reports I've read question the crystallographic arrangement found in steel beams in the rubble. All of their computer simulations have determined that the fire would have been contained because it would starve itself of oxygen and extinguish, and it surely would not have been able to get hot enough to change the nature of the steel in the way that it did.

The temps would have needed to reach 1400 degrees Celsius, or higher (I can't remember the numbers off the top of my head), and no oxygen starved jet-fuel fire (especially non jet-fuel fire, as was the case in WTC7) would ever get hot enough to do that. At least, it has never happened before, as fire has never caused the collaspe of a steel building in history, prior to 9-11!

Finally, I'm a conspiracy believer, at least in LIHOP :tinfoilhat: Thought I would let every one know, for perspective. Also, I'm a graduate student in Chemical engineering at UC Berkeley, making me unqualified to really discuss this topic, but educated enough to smell a rat.

[HysteryDiagnosis]

14. Did you see the PBS documentary that showed how the floor

beams were bolted to the wall segments?? As much as I like a good conspiracy, the special did make some sense....

[NorCalDem]

15. Yes I did

It was good. I'm not convinced of either side, conspiracy or no conspiracy. All I know is that there were many questions left unanswered that might have been able to shed light on what happened on Sept 11th. From what I've read, certain things sound fishy to me, and I'm convinced that we've been told the entire truth.

I wouldn't immediately point the finger of blame at Bush, or even someone in his administration, but it's been my experience that the people doing the covering up are also the guilty party.

Either way, with all the questions that remain unanswered, don't you think our president would want to do all he could to make sure that we do finally find out exactly how 9-11 happened.

[HysteryDiagnosis]

17. His negligence would forbid that.

[janedoe]

34. So, did every bolt reach the same melting temperature?

at exactly the same time?

If only the bolts in one area melted, why did the building come straight down?

[VTMechEngr]

21. OK, I'M GONNA SCREAM THIS

THE TEMPS DID NOT NEED TO GET TO 1400C. STEEL(AND OTHER METALS AS WELL) GET SOFTER WITH INCREASING TEMPERATURE. I.E., THE BEAMS DIDN'T MELT, THEY YIELDED! THEY GOT TOO SOFT AND THEY GAVE IN AND WARPED OR SHEARED. :banghead:

ok? Next tin foil hat to question basic material science gets a one on one lesson in the ductility and deformation of their tin foil hat under my hammer.:grr:

This is why you use fireproofing on beams and Pillars. To reply to your comment on steel buildings, perhaps you mean skyscrapers. Thousands of steel frame buildings have collapsed when on fire. I've seen an auto parts store, and a grocery store with steel frames collapse from the fire just where I live.

I understand the reasons to not believe * on 9/11. But the buildings did come down on their own.
:rant:

[pauldp]

22. So there was no reason to save the steel?

Did WTC7s collapse look ANYTHING like a controlled demolition to you?
Was there ANYTHING about it that was unusual? didn't it fall rather neatly?

Shouldn't that steel have been saved and tested?

NONE OF IT WAS SAVED.

[VTMechEngr]

54. Not much to test. It didn't melt. It justs gets weaker with heat.

Whats to test?

[pauldp]

71. Oh give me a friggin break.

A bizarre unexplained collapse occurs which looks very similar to a controlled demolition
and NONE of the steel is saved OR tested for explosive residue OR for that matter to help determine the cause of the collapse and to prevent future collapses.

NY TIMES
December 25, 2001 THE TOWERS

Experts Urging Broader Inquiry in Towers' Fall "In calling for a new investigation, some structural engineers have said that one serious mistake has already been made in the chaotic aftermath of the collapses: the decision to rapidly recycle the steel columns, beams and trusses that held up the buildings. That may have cost investigators some of their most direct physical evidence with which to try to piece together an answer.

snip
By Joe Calderone
NY Daily News Chief of Investigations
1-4-2

"A respected firefighting trade magazine with ties to the city Fire Department is calling for a "full-throttle, fully resourced" investigation into the collapse of the World Trade Center. A signed editorial in the January issue of Fire Engineering magazine says the current investigation is "a half-baked farce." The piece by Bill Manning, editor of the 125-year-old monthly that frequently publishes technical studies of major fires, also says the steel from the site should be preserved so investigators can examine what caused the collapse.

[janedoe]

61. Investigate it, if for no other reason than to avoid future law suits.

You hit it square on!

After all, if a few trashcan fires can cause a building to suddenly collapse and "vaporize," surely that's something that calls for an intense investigation. Don't you think? Even spontaneous combustion wouldn't explain any of the collapses, with our current understanding of physics (which is the best theory we have).

What's wrong with this picture?

Let's see... It's a crime scene. So, where's the "yellow tape" to mark off the evidence, so that it can be properly identified, located, and logged in as evidence? Then, there is a $7.2 Billion insurance payout, with stockholders in the insurance company who don't want to pay a fraudulent claim, right? But, more importantly, failure to investigate this puts everyone at risk (for various reasons, some more obvious than others).

Until now, whenever there has been an event with mass casualties, even if there is no one to blame, there has been an investigation. In our country (as well as others), we want to "fix it" so we can prevent "it" and make sure "it" doesn't happen again. We seek to find out what went wrong, so that it won't happen again. Why are there black boxes (flight recorders) in airplanes?

Recall the investigation into what happened to the Space Shuttle Columbia. By the way, it was an extremely impressive and thorough analysis! Not only was their logical approach and technical evaluation impressive, but they dodged all of the politics and were able to honestly present their results. http://www.nasa.gov/columbia/home/CAIB_Vol1.html

So, as pauldp has asked, "Shouldn't that steel have been saved and tested?" The Columbia investigation demonstrated how much information could be had from the smallest of parts.

So why wasn't any of the steel from WTC7 saved?

What's wrong with this picture?

[rman]

23. Steel keeps structural strength till close to melting point

Also there are plenty of examples of steel-frame high-rise buildings that did not collapse in spite of experiencing much more severe fires then the WTC buildings. ie the recent fire in Madrid.

I challenge you to come up with examples (other then WTC) of steel-frame buildings that did collapse due to fire.

It is exceedingly unlikely the buildings did come down on their own.

[Make7]

25. challenge?

rman wrote:
Steel keeps structural strength till close to melting point
Also there are plenty of examples of steel-frame high-rise buildings that did not collapse in spite of experiencing much more severe fires then the WTC buildings. ie the recent fire in Madrid.

I challenge you to come up with examples (other then WTC) of steel-frame buildings that did collapse due to fire.

Are you sure you really want to use the Windsor Tower fire as an example?

"...several top floors collapsed onto lower ones. Firefighter official Fernando Munilla expressed concern that the entire building -- which at about 106 meters (350 feet) high is among the 10 tallest in Madrid -- could collapse.

'If the partial collapses keep happening, it would be lying to say it's impossible that the whole building couldn't fall down,' he said.

Emergency crews at the scene said firefighters were waiting for the temperature inside the building to drop, which they said would lessen the danger of collapse.

At their peak, temperatures reached 800 degrees Celsius (1,472 Fahrenheit), said Javier Sanz, head of Madrid's firefighters."

http://www.cnn.com/2005/WORLD/europe/02/14/spain.block.fire

If steel melts at 2500 degrees Fahrenheit (source) and "steel keeps structural strength till close to melting point", why did part of the building collapse?
____________________

A steel framed building that collapsed due to fire:

"In Chicago, Illinois, the McCormick Place Exhibition Center collapsed as a result of a fire in 1967. In this structure, the steel-frame of the building was unprotected. The reference to McCormick Place is significant because it illustrates the fact that steel-frame buildings can collapse as a result of exposure to fire. This is true for all types of construction materials, not only steel.

Since fires do occur in high-rise buildings, building codes typically require a combination of both active systems (smoke alarms and sprinklers) and passive systems (building assemblies with hourly fire endurance ratings) as a means to protect public buildings."

http://www.iaei.org/magazine/02_d/berhinig.htm

Why do they require building assemblies with hourly fire ratings if "steel keeps structural strength till close to melting point"?

-Make7

[rman]

26. The Madrid building did not collapse like a house of cards

in spite of being enveloped in an inferno.

But the WTC buildings did collapse like a house of cards in spite of there being relatively few fires.

[StrafingMoose]

27. Point.

"'If the partial collapses keep happening, it would be lying to say it's impossible that the whole building couldn't fall down,' he said."

That implies that there was a long enough delay (long enough so he could formulate that sentence in his head) between the partial collapse and the eventual total collapse (that he projected). A delay apparently absent in **3** towers on the **same** day.

[Make7]

29. Did something other than fire cause the partial collapse?

If the temperature of the fire in the Windsor Tower only reached 60% of the melting point of steel and, as you say, "steel keeps structural strength till close to melting point", then why did part of the building collapse?

-Make7

[rman]

31. it was a -partial- collapse, after many hours of raging fires

how does that compare to complete collapse after about one hour of limited fires (WTC 1 and 2), and several hours of limited fires (WTC7).

[Make7]

73. Please explain the partial collapse.

In your post, Steel keeps structural strength till close to melting point, you brought up the example of the Windsor Tower.

Since you state that steel keeps its strength until close to the melting point, and the fire in the Windsor Tower only reached about 60% of the melting point of steel, how did a partial collapse occur?

If it was not caused by the fire, what was the cause of the partial collapse?

-Make7

[petgoat]

74. WIndsor Tower Partial Collapse

Windsor Tower is reinforced concrete, not steel frame construction.
Fire can cause concrete to split and chip.

[Make7]

77. Then why is it being used as an example.....

that steel-framed skyscapers do not fall due to fire?

www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=125&topic_id=48998&mesg_id=49021
_____________________

And why do these guys think the steel perimeter columns failed?

Failure of the structure happened with the collapse of the steel perimeter columns which resulted in the floor slabs collapsing as the edge support was taken away. The massive concrete transfer slab at the 20th floor prevented further progressive failure. However, as the debris fell the cladding below was smashed and the fire spread to lower floors.

http://www.concretecentre.com/main.asp?page=827

-Make7

[carlvs]

78. And if you think that's something...

Take a look at the before-and-after photos they have in the Wikipedia entry of this fire...

[petgoat]

39. challenge

Masonry retail stores with steel roofs and the McCormick Center don't
count. If I'm not mistaken McCormick was a space-frame pavilion. The
light roof framing these kinds of structures use are in no way
comparable to the massive steel skeletons of skyscrapers.

[Make7]

72. criteria

rman wrote in Post #23:
I challenge you to come up with examples (other then WTC) of steel-frame buildings that did collapse due to fire.

• The McCormick Place Exhibition Center was a steel-frame building.
  
• The McCormick Place Exhibition Center collapsed due to fire.

Please explain how that example does that not meet the criteria of the challenge?

-Make7

[petgoat]

75. It wasn't my challenge, so I don't make the rules

but I just wanted to point out that a pavilion or an aircraft hanger
or a supermarket is a different proposition from a highrise office
building. Normally the roofs of these lower buildings are steel-framed
and not fireproofed as the assumption is made that people can evacuate
and that the structure can collapse without endagering other buildings.

http://www.chipublib.org/004chicago/disasters/mccormick_fire.html

A high rise structure must be rigorously fireproofed to try to prevent
it from damaging other structures and endangering lives.

[Make7]

76. But you said my example didn't count anyway. ( n/t )

[carlvs]

30. Typical CTer rejection of basic science!

I would like to know what source you got this info on how steel behaves in a fire. I am pretty sure that these researchers over at the University of Manchester like to know that the info they have on their website is all wrong:

"Hot finished carbon steel begins to lose strength at temperatures above 300°C and reduces in strength at steady rate up to 800°C. The small residual strength then reduces more gradually until the melting temperature at around 1500°C. This behaviour is similar for hot rolled reinforcing steels. For cold worked steels including reinforcement, there is a more rapid decrease of strength after 300°C... In addition to the reduction of material strength and stiffness, steel displays a significant creep phenomena at temperatures over 450°C. The phenomena of creep results in an increase of deformation (strain) with time, even if the temperature and applied stress remain unchanged...

And of course all the graphs they make available on the site's various pages that show the strength of the types of steel they have tested falls like a rollercoaster drop as the temperature increases are all just window dressing... :sarcasm:

[janedoe]

32. Perhaps steel shatters when it gets hot.

Is this what steel looks like when it yields, gets soft, and sags from being too hot?


Where is the plastic deformation?
I see brittle failure, not ductile failure.

[VTMechEngr]

53. The main mass is falling through the middle

peeling the outer steel structure out and off the building. Don't forget that the WTC had a unique design vs other sky scrapers.

It lost ~40% of its structure in crash due to design. Then the trusses holding the floors warped due to heat. FIY. Whether you choose to believe me or not, trusses warp in even low heat. Now, whats left to hold the same mass of building up. Let that fire weaken the steel (Materials science FACT!) and all it takes is one section going and once that huge mass is falling its F=MA baby. Doesn't matter how strong the steel is, that force exceeds the yield strength and the whole structure went down. Why straight down? Why not? Simple statics says that was the way gravity was pulling. Did you see a horizontal force?


Few engineers post in this forum cause we'd go fucking mad!

[petgoat]

37. "THEY GOT TOO SOFT AND THEY GAVE IN AND WARPED OR SHEARED"

There's no evidence for your theory. Black smoke shows an
oxygen-deprived fire. The NIST report says steel samples showed
"limited exposure if any above 250 degrees C."

ht tp://wtc.nist.gov/pubs/NCSTAR1-3ExecutiveSummary.pdf

(see p. 6 of the .pdf)

[mandog]

41. Doesn't plastic burn with a black smoke?

For that matter what about computers, cables and synthetic furnishings?

[hack89]

60. Do you accept this document as accurate?

If so, how do you explain the lack of any damage indicative of explosive cutting of steel?

And you conveniently glossed over this gem:

however, these columns represented only 3 percent of the perimeter columns on the floors involved in fire and cannot be considered representative of other columns on these floors.

[petgoat]

62. "how do you explain the lack of any damage indicative of explosive"

I don't know where NIST got their samples, or who decided what to
select. Most of the steel, you'll recall, was shipped to China post
haste.

Apparently NIST didn't examine the WTC7 steel from the FEMA Appendix 3
that showed corrosive attack and unexplained presence of compounds of copper and iron with sulfur.

http://911research.wtc7.net/wtc/evidence/metallurgy/

[janedoe]

63. The big question...

You said, "I don't know where NIST got their samples,..."

Do you think NIST does? :shrug:

[hack89]

68. And what is electric wiring made of? Copper perhaps?

And steel is an iron alloy (iron plus carbon). Also Iron oxides are used in the production of magnetic storage in computers.

The sulphur? Gypsum from the sheet rock:

Drywall (also called wallboard, gypsum board, GWB, plasterboard, SHEETROCK® and Gyproc®) is a building material consisting of gypsum formed into a flat sheet and sandwiched between two pieces of heavy paper

http://en.wikipedia.org/wiki/Drywall

sulfates:

Sulfate is the IUPAC name for the SO42- ion, consisting of a central sulfur atom single bonded to four tetrahedrally oriented oxygen atoms.

http://en.wikipedia.org/wiki/Sulfate

The calcium carbonate of the limestone produces pH-neutral calcium sulfate that is physically removed from the scrubber. That is, the scrubber turns sulfur pollution into industrial sulfates.

In some areas the sulfates are sold to chemical companies as gypsum when the purity of calcium sulfate is high. In others, they are placed in a land-fill

http://en.wikipedia.org/wiki/Acid_rain

[philb]

45. the temperatures were not hot enough for long enough to cause major loss

of strength by the massive steel beams.

See the picture of the people walking around on the floor where the plane hit soon after the crash in WTC1 and the statements of the firefighters in WTC2 that the fires were small, isolated, and controllable. The temperatures never got hot enough to have a major effect on the strength of the beams.

The kerosene fires were very short lived, and the residual fires not as hot as in a lot of other fires. The buildings were designed to withstand such crashes and fires. I've seen no evidence that the fires had anything to do with the destruction of the WTC buildings.
The pictures, videos, and witnesses make it pretty clear that the destruction of the buildings was caused by explosions.

[janedoe]

36. Well done!

...and we saw few broken (open) windows in WTC7.

[Pepperbelly]

10. I think it wouild tend to bank it ...

like coals in a wood stove or fireplace or campfire.

Far more experience with those than with massive rubble.

[LSK]

11. the heat would have to decrease over time unless...

there was a source of energy to generate more heat. Heat ALWAYS flows from hot to cold. How fast it does depends on the materials heat transfer rate surrounding the heat source.

And also, what were the hot spots temps after 1 day?? After 5 days???

I have a BA in Mechanical Engineering in 97 but I went into a different field out of college.

[usregimechange]

16. You have to prevent warp core breech first!

[Land Shark]

18. Like a layer of crackers on top of soup

rubble is going to do two things at once: insulate heat underneath as well as absorb and conduct heat away. material properties and densities will dictate the relative rates of each, along with material burning, etc.

One thing that needs consideration or adjustment is the temperature of burning jet fuel. Things can burn at a higer than normal temperature with certain impurities added (perhaps jet fuel with paper/wood) and that higher temperature can be maintained even after the impurity has been consumed.

so the analysis can not be as simple as: jet fuel burns at X temp, but structural steel melts at Y, therefore no melting possible.

[VTMechEngr]

20. I'm an engineer. Q. is not thermodynamics, but Heat Transfer

Thermodynamics is Heat and energy, like cycles.

A.

1. Yes. q=-k(deltaT) It actually uses nasty partial differentials, but hey, in math, its a 1-dimensional world.;) In truth, you need another equation to solve, since we have 2 unknowns, but I'm sure we could measure q or enough other info for another approach.


2. Depends. If it chokes off the oxygen, then no. If oxygen can still get in, well, then you have a thermal blanket holding the heat in. The k above is a thermal conductivity. Good enough rubble with a low k could have held the heat in for a long time.

[LARED]

24. Bingo; we hve a winner

I hope you win a prize for the correct answer.

[Ezlivin]

28. Heat transfer also happens at the point of impact

In other words, the steel structure that surrounded the site of impact acted to transfer heat away from the area.

This handbook describes a full-scale fire test conducted on a 36m × 12m four-storey steel-framed school building on the premise of Perwaja Steel Sdn. Bhd., Gurun, Kedah in May 8, 2001. No fire protection was applied on the structural steel. The primary objective of the fire test was to study the behaviour of structural steel in real fire.

During the fire, even though the room temperature in the fire compartment measuring 15m × 9m reached more than 900°C, the steel temperature barely reached 700°C. Despite the elevated room temperature, the steel structure maintained its stability and integrity due to restraining effect of unheated steel members.

The test demonstrated the inherent fire resistance of unprotected hot-rolled steel framed building to justify the use of unprotected steel. Many fire engineers have agreed to include performance based concept in the construction industry as it has significant effect in reducing cost.

http://www.penerbit.utm.my/cgi-bin/katalog/buku.cgi?id=...

Notice how the "restraining effect of unheated steel members" maintained the building's integrity? Both of the WTCs had massive amounts of steel that was "unheated."

[janedoe]

33. Evidence of WTC1's room temperature

Note the woman standing in the impact zone and looking out.



How hot could it be in there? (Note here hair is not burned off, nor are her clothes.)

[LARED]

35. What a totally phony argument

So what if there is someone standing in a burned out (note the past tense) area of the building. There is no fire anywhere near her.

[janedoe]

38. Hint: Steel does not burn...

in a way as to fuel a fire.

Read post #28 (to which I was responding).
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=125&topic_id=48998&mesg_id=49073

The room temperature reached "more than 900°C" for the steel temperature of "barely 700°C."

So, where's the evidence of such heat in WTC1?

[mandog]

40. Unless it was used to store firewood and gasoline..

I think the Madrid skyscraper that burned holds your answer. Just like the WTC or any other office building it burned like kindling because it was packed with combustibles like paper and office furnishings. IRCC such fires easily reach 1000 degrees C.

I mean - you do believe that Madrid is the perfect model for how the WTC should have behaved don't you?

[janedoe]

43. Madrid fire not like WTC

Look at the pictures in post #33.
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=125&topic_id=48998&mesg_id=49098
Does it look like a raging fire?

How can it be 1000°C and not have her clothing burn? I think the typical temperature for baking a turkey in an oven is 325°F. (163°C) Depending on the size bird, it can take several hours.
(Heat transfer problem) But, clearly, the woman in the picture is not being cooked.

So, where's the heat?

[hack89]

44. So a picture showing a tiny fraction of the WTC proves what? n/t

[philb]

48. A big deal was made about the plane/fuel/etc.; this shows the area

of maximum impact of the plane had little long term temperature increase.

Where are you suggesting the hot fires are? where is the evidence supporting this?

As noted before, the firefighters who were in the area of impact in WTC2 said small, controllable fires; not something that would cause major effect on the massive steel beams.

[hack89]

49. Start on page 22

http://www.fema.gov/pdf/library/fema403_ch2.pdf Take a close look at how they calculated the energy output of both fires.

[janedoe]

55. You already used that one

The last two times you wanted to see more of the building, I went to the trouble of posting a picture for you, on two different occasions.

This is your last opportunity.

Please review my post#99, (in response to your post #95):
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=125&topic_id=47806&mesg_id=48580

and again in my post #98
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=125&topic_id=47806&mesg_id=48578

[hack89]

57. Nice misdirection then too..

we were talking about the post collapse hot spots if I recall - I showed that there were fires in the rubble pile for weeks after the collapse and you interject an completely irrelevant post about how the fires in the towers weren't hot enough.

Here is how hot the fires were:

The modeling suggests a peak total rate of fire energy output on the order of 3-5 trillion Btu/hr, around 1-1.5 gigawatts (GW), for each of the two towers. From one third to one half of this energy flowed out of the structures. This vented energy was the force that drove the external smoke plume. The vented energy and accompanying smoke from both towers combined into a single plume. The energy output from each of the two buildings is similar to the power output of a commercial power generating station. The modeling also suggests ceiling gas temperatures of 1,000 degrees Centigrade (1,800 degrees Fahrenheit) with an estimated confidence of plus or minus 100 degrees Centigrade (200 degrees Fahrenheit) or about 900-1,100 degrees Centigrade (1,600-2,000 degrees Fahrenheit).

The viability of a 3-5 trillion Btu/hr (1-1.15 GW) fire depends on the fuel and air supply. The surface area of office contents needed to support such a fire ranges from about 30,000-50,000 square feet, depending on the composition and final arrangement of the contents and the fuel loading present. Given the typical occupied area of a floor as approximately 30,000 square feet, it can be seen that simultaneous fire involvement of an area equal to 1-2 entire floors can produce such a fire. Fuel loads are typically described in terms of the equivalent weight of wood. Fuel loads in office-type occupancies typically range from about 4-12 psf, with the mean slightly less than 8 psf (Culver 1977). File rooms, libraries, and similar concentrations of paper materials have significantly higher concentrations of fuel. At the burning rate necessary to yield these fires, a fuel load of about 5 psf would be required to provide sufficient fuel to maintain the fire at full force for an hour, and twice that quantity to maintain it for 2 hours. The air needed to support combustion would be on the order of 600,000-1,000,000 cubic feet per minute.

Air supply to support the fires was primarily provided by openings in the exterior walls that were created by the aircraft impacts and fireballs, as well as by additional window breakage from the ensuing heat of the fires

http://www.fema.gov/pdf/library/fema403_ch2.pdf

[philb]

47. don't know if you are serious, but there's no evidence WTC fires were very

hot; not nearly as hot as many other fires. After the brief period when the kerosene exploded/burned; which lasted a very short time.

[hack89]

50. Are you saying that with all that burning jet fuel...

none of the combustibles in all those offices ignited? I find that hard to believe - if I spread five gallons of gas in my living room and lit it I would expect my house to burn down. If there was as much burnable material in the WTC as the Madrid building then it must have burned just as hot. Anything else beggars the imagination.

[VTMechEngr]

51. Steel can burn, but in a fire, no.

Steel can burn. Light a steel wool pad and watch it burn up like paper. Really cool. Thats what happens when you use a cutting torch.

[janedoe]

56. Please read my post more carefully

Hint: Steel does not burn...
in a way as to fuel a fire.

[LARED]

58. Did anyone say it was fueling a fire?

Here's a hint ( I shouldn't have to tell a structural engineer and materials expert) this but here goes.

One test that shows a fire where room temperature reached 900 degrees while the steel barely reached 700 degrees is meaningless. Was it a similar steel structure, was it a tube in tube design, was it damaged by a large jet impacting, was it a building 110 stories tall? One fire test with no indication of building standards used or design criteria is meaningless

As a structural engineer and materials expert you also know that steel at 700 degrees C has lost most of its strength, so there is NO need for evidence for temperatures that high (not heat; another thing a structural engineer and materials expert should understand) to have a highly negative effect on the load bearing capacity of the steel.

[Ezlivin]

66. The test is not meaningless

Unless you think that tests designed and carried out by professional engineers signify nothing. The reason the test is meaningful is because the results from a four-story structure can be applied to much larger structures.

There is much mention over the "unusual" design of the WTC. In fact, this is always brought up to counter the argument that other structural steel buildings have not collapsed after fires. And the design of the WTC must have been truly exceptionally unique in that it collapsed within roughly sixty minutes.

I can dump a lot of heat into a room, but if its structure simply transfers the heat away (through excellent conductivity), I can't expect that the contents will receive as much heat as it would without such a structure. (A fire burning in a wooden structure has no mechanical means to transfer the heat away from the source; a steel-framed building is perfectly capable of transferring large amounts of heat away from the source.)

I don't believe that the temperatures ever rose high enough for long enough to cause structural damage that would lead to collapse. The presence of black smoke indicates a partially smothered or struggling fire; the presence of people at the entry point of the aircraft indicates that the temperature was low, and; the color of the fire indicates that it was not hot burning (just as a spectral analysis of distant stars can reveal their temperature and composition measured solely by color).

If professional firemen, with their lives on the line, can say that they can knock down a fire with a couple of hoses, then they didn't see a blazing inferno, but a controllable fire. While some may argue that their diagnosis was proven faulty, the firefighters are among the few eyewitnesses that reported the condition of the fire at the scene. And unlike other eyewitnesses, the firemen were professionals who knew what fires and their intensity looked like.

[hack89]

67. I am encouraged by your faith in engineering testing and modeling..

What is you opinion of this modeling done to determine the fires needed to create the smoke plumes over the WTC towers as they burned.

3 to 5 trillion Btu per hour seems like a lot of heat to me.

The modeling suggests a peak total rate of fire energy output on the order of 3-5 trillion Btu/hr, around 1-1.5 gigawatts (GW), for each of the two towers. From one third to one half of this energy flowed out of the structures. This vented energy was the force that drove the external smoke plume. The vented energy and accompanying smoke from both towers combined into a single plume. The energy output from each of the two buildings is similar to the power output of a commercial power generating station. The modeling also suggests ceiling gas temperatures of 1,000 degrees Centigrade (1,800 degrees Fahrenheit) with an estimated confidence of plus or minus 100 degrees Centigrade (200 degrees Fahrenheit) or about 900-1,100 degrees Centigrade (1,600-2,000 degrees Fahrenheit).

The viability of a 3-5 trillion Btu/hr (1-1.15 GW) fire depends on the fuel and air supply. The surface area of office contents needed to support such a fire ranges from about 30,000-50,000 square feet, depending on the composition and final arrangement of the contents and the fuel loading present. Given the typical occupied area of a floor as approximately 30,000 square feet, it can be seen that simultaneous fire involvement of an area equal to 1-2 entire floors can produce such a fire. Fuel loads are typically described in terms of the equivalent weight of wood. Fuel loads in office-type occupancies typically range from about 4-12 psf, with the mean slightly less than 8 psf (Culver 1977). File rooms, libraries, and similar concentrations of paper materials have significantly higher concentrations of fuel. At the burning rate necessary to yield these fires, a fuel load of about 5 psf would be required to provide sufficient fuel to maintain the fire at full force for an hour, and twice that quantity to maintain it for 2 hours. The air needed to support combustion would be on the order of 600,000-1,000,000 cubic feet per minute.

Air supply to support the fires was primarily provided by openings in the exterior walls that were created by the aircraft impacts and fireballs, as well as by additional window breakage from the ensuing heat of the fires

[philb]

46. So where are the hot fires; its clear it has little to do with the gasoli

There is no theoretical basis or evidence at the site to indicate
that there were any fires hot enough for long enough to have any major effect on the strength of the steel beams.


The effect of rubble depends on whether the heat source was a fire under the rubble; oxygen supply and fuel source important to continued burn.

And if no fire, but something like molten metal, the conductivity of the rubble would affect how fast the heat is conducted away from the heat source, along with access to air.

[hack89]

59. There is certainly a theoretical basis...

start at page 21.

http://www.fema.gov/pdf/library/fema403_ch2.pdf

As for the rubble, there were combustion products being detected weeks after the collapse. Combustion products = combustion = fires, seems simple to me. Molten steel wouldn't be producing combustion products now would they?

Combustion products continued to be emitted from the debris pile in the ensuing months. Dust was "no longer part of the plume per se after about day three or four because the rains came and washed some of the dust and smoke away," Lioy said. What was left were smoldering fires.

The fires, which began at over 1,000 °C, gradually cooled, at least on the surface, during September and October 2001. USGS's AVIRIS also measured temperatures when it flew over ground zero on Sept. 16 and 23. On Sept. 16, it picked up more than three dozen hot spots of varying size and temperature, roughly between 500 and 700 °C. By Sept. 23, only two or three of the hot spots remained, and those were sharply reduced in intensity, Clark said.

However, Clark doesn't know how deep into the pile AVIRIS could see. The infrared data certainly revealed surface temperatures, yet the smoldering piles below the surface may have remained at much higher temperatures. "In mid-October, in the evening," said Thomas A. Cahill, a retired professor of physics and atmospheric science at the University of California, Davis, "when they would pull out a steel beam, the lower part would be glowing dull red, which indicates a temperature on the order of 500 to 600 °C. And we know that people were turning over pieces of concrete in December that would flash into fire--which requires about 300 °C. So the surface of the pile cooled rather rapidly, but the bulk of the pile stayed hot all the way to December."

http://pubs.acs.org/cen/NCW/8142aerosols.html

[LARED]

65. You're kidding right?

There is no theoretical basis or evidence at the site to indicate that there were any fires hot enough for long enough to have any major effect on the strength of the steel beams.

If there is no theoretical basis for fires fueled by normal office combustibles why are building required to fireproof steel? For giggles? Because uncle Joe has an insulation business? Why are hundreds of thousands of steel structures fire proofed if there is no basis for fires to get hot enough to affect the steel?

There is plenty of evidence for fires in all the WTC buildings. One needs to be willfully ignorant to believe otherwise.

[VTMechEngr]

52. Notice the height!

4 stories. Add another 16 or more to that and the load levels are a different story. I would like to say that I think the world trade centers held up well, considering that 40% or more of the structure was blasted away.

[MrSammo1]

64. Sounds

More like a question one would ask a physicist.

[hack89]

70. Lack of expertise was never stopped anyone on this forum...

from contributing their two cents worth - one of the charms of this board as far as I'm concerned.