clare at snyder.on.ca wrote:

Exactly what happened , but the weakest point (also initially the
strongest, and the most vulnerable in that building design, was the
core, or elevator shaft. It just happenned the plane penetrated far
enough that the fire and physical damage weakened the core enough to
bring the stry above down. The impact of the center of the next floor
up falling collapsed the next floor of the "core" and it just came
down, top to bottom, like an accordian.

A demolition expert would have brought it down from the
bottom.(generally)
The engineer responsible for the design explained in painful detail
the structural "deficiency" that allowed this to happen. A totally
unforseen, and almost unforseable chain of events that played directly
into the particular structural quirks of the design.

(reduced to just metalworking to aviod the loons -
and it's kinda sorta on topic here)

No argument with anything you wrote here, clare.

Just a reminder that if it isn't in the design requirements, it's not
really a "deficiency".

I don't think it's possible to build an economically viable commercial
building that size that can survive a jet attack of that kind.


YMMV

Richard

On Nov 2, 3:43 am, cavelamb himself wrote:
clare at snyder.on.ca wrote:
Exactly what happened , but the weakest point (also initially the
strongest, and the most vulnerable in that building design, was the
core, or elevator shaft. It just happenned the plane penetrated far
enough that the fire and physical damage weakened the core enough to
bring the stry above down. The impact of the center of the next floor
up falling collapsed the next floor of the "core" and it just came
down, top to bottom, like an accordian.

A demolition expert would have brought it down from the
bottom.(generally)
The engineer responsible for the design explained in painful detail
the structural "deficiency" that allowed this to happen. A totally
unforseen, and almost unforseable chain of events that played directly
into the particular structural quirks of the design.

(reduced to just metalworking to aviod the loons -
and it's kinda sorta on topic here)

No argument with anything you wrote here, clare.

Just a reminder that if it isn't in the design requirements, it's not
really a "deficiency".

I don't think it's possible to build an economically viable commercial
building that size that can survive a jet attack of that kind.

YMMV

Richard
I think it was designed to survive a 727 with a partial fuel (lost in
the fog after a long trip?) rather than a not-yet-designed larger
plane with nearly the full takeoff load.
Also, Robert Moses was powerful enough to bulldoze his pet project
through despite theoretical engineering objections. If you want to
unearth REAL conspiracies, dig into NYC Dem politics, beginning with
Tammany Hall.

Has to do with volume and speed of air ... the same as bellows that were
used in blacksmithing.

Years ago a neighbors house burned down and the metal beams actually melted
.... not twisted but melted..
That was from just wood and air

On Fri, 02 Nov 2007 02:43:48 -0500, cavelamb himself
wrote:

clare at snyder.on.ca wrote:

Exactly what happened , but the weakest point (also initially the
strongest, and the most vulnerable in that building design, was the
core, or elevator shaft. It just happenned the plane penetrated far
enough that the fire and physical damage weakened the core enough to
bring the stry above down. The impact of the center of the next floor
up falling collapsed the next floor of the "core" and it just came
down, top to bottom, like an accordian.

A demolition expert would have brought it down from the
bottom.(generally)
The engineer responsible for the design explained in painful detail
the structural "deficiency" that allowed this to happen. A totally
unforseen, and almost unforseable chain of events that played directly
into the particular structural quirks of the design.





(reduced to just metalworking to aviod the loons -
and it's kinda sorta on topic here)

No argument with anything you wrote here, clare.

Just a reminder that if it isn't in the design requirements, it's not
really a "deficiency".


That's why "deficiency" is in quotes.

I don't think it's possible to build an economically viable commercial
building that size that can survive a jet attack of that kind.


YMMV

Richard


--
Posted via a free Usenet account from http://www.teranews.com

On Fri, 02 Nov 2007 15:35:54 GMT, "cncfixxer1"
wrote:

Has to do with volume and speed of air ... the same as bellows that were
used in blacksmithing.

Years ago a neighbors house burned down and the metal beams actually melted
... not twisted but melted..
That was from just wood and air

Firefighter friends say they would much rather go into a burning
building with a wood framed roof than a metal frame.
Wood chars from the outside in, and you can see when it is getting
weak. Steel loses it's strength all at one when it reaches a given
temperature, and it turns into a nasty pot of spagetti all at once.


--
Posted via a free Usenet account from http://www.teranews.com

After a Computer crash and the demise of civilization, it was learned
"cncfixxer1" wrote on Fri, 02 Nov 2007 15:35:54
GMT in rec.crafts.metalworking :
Has to do with volume and speed of air ... the same as bellows that were
used in blacksmithing.

Years ago a neighbors house burned down and the metal beams actually melted
... not twisted but melted..
That was from just wood and air

Stainless steel grills are suppose to stand up to bbq fires. They
do, but not when the fire is augmented with coal and a forced draft.
--
pyotr filipivich
"Quemadmoeum gladuis neminem occidit, occidentis telum est. "
Lucius Annaeus Seneca, circa 45 AD
(A sword is never a killer, it is a tool in the killer's hands.)

In article ,
pyotr filipivich wrote:

After a Computer crash and the demise of civilization, it was learned
"cncfixxer1" wrote on Fri, 02 Nov 2007 15:35:54
GMT in rec.crafts.metalworking :
Has to do with volume and speed of air ... the same as bellows that were
used in blacksmithing.

Years ago a neighbors house burned down and the metal beams actually melted
... not twisted but melted..
That was from just wood and air

Stainless steel grills are suppose to stand up to bbq fires. They
do, but not when the fire is augmented with coal and a forced draft.

It needn't even require forced draft. Some African blacksmiths use
charcoal fired forges made of tile pipe hanging from a tree limb or
another handy support.

The pipe has a grate and is open bottom to top with a hole in the side
for the smith to insert workpieces.

Just the natural draft from the heated air up the pipe drawing in cool
air at the bottom can keep the forge hot enough to burn/melt steel.

Way I figure it, the natural draft from the fires in the two main WTC
buildings was probably more than enough to generate enough heat to
weaken the floor trusses. When one gave way, everything above that
slammed into those floors and all of that pancaked into the lower floors.

No conspiracy needed, just lots of fuel and natural draft from the
chimney effect of a tall building with big holes in its sides.

On Nov 2, 8:28 pm, John Husvar wrote:
In article ,
pyotr filipivich wrote:

After a Computer crash and the demise of civilization, it was learned
"cncfixxer1" wrote on Fri, 02 Nov 2007 15:35:54
GMT in rec.crafts.metalworking :
Has to do with volume and speed of air ... the same as bellows that were
used in blacksmithing.

Years ago a neighbors house burned down and the metal beams actually melted
... not twisted but melted..
That was from just wood and air

Stainless steel grills are suppose to stand up to bbq fires. They
do, but not when the fire is augmented with coal and a forced draft.

It needn't even require forced draft. Some African blacksmiths use
charcoal fired forges made of tile pipe hanging from a tree limb or
another handy support.

The pipe has a grate and is open bottom to top with a hole in the side
for the smith to insert workpieces.

Just the natural draft from the heated air up the pipe drawing in cool
air at the bottom can keep the forge hot enough to burn/melt steel.

Way I figure it, the natural draft from the fires in the two main WTC
buildings was probably more than enough to generate enough heat to
weaken the floor trusses. When one gave way, everything above that
slammed into those floors and all of that pancaked into the lower floors.

No conspiracy needed, just lots of fuel and natural draft from the
chimney effect of a tall building with big holes in its sides.

Sorry, but there's not the slightest chance that fire contributed
meaningfully to the collapse of WTC2, because:

1) There was little or no jet fuel in the building.

2) The carpets and furniture were fire resistant.

3) Even if there was an adequate supply of readily combustible fuel
present, 56 minutes is not enough time to develop a fire intense
enough or large enough in extent to weaken the steel enough, given the
thermal mass of steel and concrete present (every floor had hundreds
of thousands of kg of steel and over one million kg of concrete).

On Sat, 03 Nov 2007 09:28:22 -0700, wrote:


1) There was little or no jet fuel in the building.

Aparet from the 70,000kg carried on the plane...
2) The carpets and furniture were fire resistant.
Doesn't matter. Firslty fire resistance is generlly to limit flame spread -
it will still burn. I woudl also be surprised if the furnitreu and carpets
were especially fire resistant, unless it was required by the building
code. Given the sprinkler system, there isn't much point from a fire
engineering perspective.
There is PLENTY of other fuel (beside the jet fuel) in an office - paper,
desks, wooden fittings, panelling, softboard ceiling tiles, etc.
3) Even if there was an adequate supply of readily combustible fuel
present, 56 minutes is not enough time to develop a fire intense
enough or large enough in extent to weaken the steel enough, given the
thermal mass of steel and concrete present (every floor had hundreds
of thousands of kg of steel and over one million kg of concrete).
Sure it is. The floors were supported on relatively lightweight trusses,
whcih have a lot of expeosed area (high surface to cross section ratio)-
this means it will heat up fast.
a 610UB will reach 500 deg C in around 9 minutes in a "standard" fire, at
which point it has around 20% of the original strecnght. Steel starts to
weaken around 300 deg C. If you want the exact figures, it will have to
wait until Monday when I am back at work.
More importanly for the WTC collapse was the connections of the trusses at
each end - to the central core and the vertical columns at the preimeter.
These failed (rather than the trusses) so theends failed in sear, so the
collapesed straight down - hence the pancake.

Geoff M (B.E(mech), ME (Fire)).

On Sat, 03 Nov 2007 09:28:22 -0700, wrote:

On Nov 2, 8:28 pm, John Husvar wrote:
In article ,
pyotr filipivich wrote:

After a Computer crash and the demise of civilization, it was learned
"cncfixxer1" wrote on Fri, 02 Nov 2007 15:35:54
GMT in rec.crafts.metalworking :
Has to do with volume and speed of air ... the same as bellows that were
used in blacksmithing.

Years ago a neighbors house burned down and the metal beams actually melted
... not twisted but melted..
That was from just wood and air

Stainless steel grills are suppose to stand up to bbq fires. They
do, but not when the fire is augmented with coal and a forced draft.

It needn't even require forced draft. Some African blacksmiths use
charcoal fired forges made of tile pipe hanging from a tree limb or
another handy support.

The pipe has a grate and is open bottom to top with a hole in the side
for the smith to insert workpieces.

Just the natural draft from the heated air up the pipe drawing in cool
air at the bottom can keep the forge hot enough to burn/melt steel.

Way I figure it, the natural draft from the fires in the two main WTC
buildings was probably more than enough to generate enough heat to
weaken the floor trusses. When one gave way, everything above that
slammed into those floors and all of that pancaked into the lower floors.

No conspiracy needed, just lots of fuel and natural draft from the
chimney effect of a tall building with big holes in its sides.

Sorry, but there's not the slightest chance that fire contributed
meaningfully to the collapse of WTC2, because:

1) There was little or no jet fuel in the building.

2) The carpets and furniture were fire resistant.

3) Even if there was an adequate supply of readily combustible fuel
present, 56 minutes is not enough time to develop a fire intense
enough or large enough in extent to weaken the steel enough, given the
thermal mass of steel and concrete present (every floor had hundreds
of thousands of kg of steel and over one million kg of concrete).

Come now, the aircraft were carrying heavy fuel loads and in addition
there was a large diesel fuel in at least one of the buildings for the
back-up generators.

In fact, contrary to the conspiracy theorists arguments of "cover up"
there have been a number of studies published in peer reviewed
journals. I read one in either the Civil Engineering or Mechanical
Engineering Association's publication that was extremely detailed in
describing both the failures and the causes of the failures.

The article questioned both the design and construction of the Towers
and speculated about whether it would be possible to build a tower
that would be proof against another such incident.

Journals of this sort are read by a very large percentage of working
engineers and if there had been either faulty details or calculations
in the article I'm sure that someone, somewhere, would have commented
on it.

One of the things that seems so strange about the whole conspiracy
theory is that the majority of the people that subscribe to it are not
professional engineers and, quite simply, do not have enough technical
knowledge to evaluate the event.



Bruce-in-Bangkok
(Note:displayed e-mail
address is a spam trap)

On Nov 4, 1:36 am, Geoff wrote:
On Sat, 03 Nov 2007 09:28:22 -0700, wrote:

1) There was little or no jet fuel in the building.

Aparet from the 70,000kg carried on the plane...

Actually, no; that burnt up in a fireball outside the building. That's
clear from the several videos of the impact of Flight 175.
To create a fireball 75 ft in diameter with jet fuel (which is about
the diameter of the fireball as gauged by the known size of the
building), requires about 10.000 gallons (assuming a lower
flammability limit of about 0.6% by volume), which is the amount NIST
estimates was present at impact.


2) The carpets and furniture were fire resistant.

Doesn't matter. Firslty fire resistance is generlly to limit flame spread -
it will still burn.

But unless the temperature is very high, it will not PROPAGATE, which
was most likely the case.

I woudl also be surprised if the furnitreu and carpets
were especially fire resistant, unless it was required by the building
code. Given the sprinkler system, there isn't much point from a fire
engineering perspective.
There is PLENTY of other fuel (beside the jet fuel) in an office - paper,

Modern offices are not loaded with paper like they were years ago. And
the paper that is there is usually inside filing cabinets etc.; it's
certainly not "readily available".

desks, wooden fittings, panelling, softboard ceiling tiles, etc. 3) Even if there was an adequate supply of readily combustible fuel
present, 56 minutes is not enough time to develop a fire intense
enough or large enough in extent to weaken the steel enough, given the
thermal mass of steel and concrete present (every floor had hundreds
of thousands of kg of steel and over one million kg of concrete).

Sure it is. The floors were supported on relatively lightweight trusses,
whcih have a lot of expeosed area (high surface to cross section ratio)-
this means it will heat up fast.

Not a chance. Too much thermal mass there. Way too much. You can't
selectively heat what you want without heating everything else in the
vicinity, e.g., concrete. Look up the Stefan-Boltzmann law. Hot
surfaces start radiating away huge amounts of power to the
surroundings...the power scales as T^4.

a 610UB will reach 500 deg C in around 9 minutes in a "standard" fire, at
which point it has around 20% of the original strecnght. Steel starts to
weaken around 300 deg C. If you want the exact figures, it will have to
wait until Monday when I am back at work.

I already looked it up. It losses about 10% at 300 degrees C. Nowhere
near enough, and it's doubtful the fire even reached that temp over
any appreciable area in the first place.


More importanly for the WTC collapse was the connections of the trusses at
each end - to the central core and the vertical columns at the preimeter.
These failed (rather than the trusses) so theends failed in sear, so the
collapesed straight down - hence the pancake.

Well, IIRC, that's not what NIST is claiming. In fact they're claiming
an inferno of 1000 degrees centigrade, and that's pure nonsense.

On Nov 4, 3:59 am, Bruce in Bangkok wrote:
On Sat, 03 Nov 2007 09:28:22 -0700, wrote:
On Nov 2, 8:28 pm, John Husvar wrote:
In article ,
pyotr filipivich wrote:

After a Computer crash and the demise of civilization, it was learned
"cncfixxer1" wrote on Fri, 02 Nov 2007 15:35:54
GMT in rec.crafts.metalworking :
Has to do with volume and speed of air ... the same as bellows that were
used in blacksmithing.

Years ago a neighbors house burned down and the metal beams actually melted
... not twisted but melted..
That was from just wood and air

Stainless steel grills are suppose to stand up to bbq fires. They
do, but not when the fire is augmented with coal and a forced draft.

It needn't even require forced draft. Some African blacksmiths use
charcoal fired forges made of tile pipe hanging from a tree limb or
another handy support.

The pipe has a grate and is open bottom to top with a hole in the side
for the smith to insert workpieces.

Just the natural draft from the heated air up the pipe drawing in cool
air at the bottom can keep the forge hot enough to burn/melt steel.

Way I figure it, the natural draft from the fires in the two main WTC
buildings was probably more than enough to generate enough heat to
weaken the floor trusses. When one gave way, everything above that
slammed into those floors and all of that pancaked into the lower floors.

No conspiracy needed, just lots of fuel and natural draft from the
chimney effect of a tall building with big holes in its sides.

Sorry, but there's not the slightest chance that fire contributed
meaningfully to the collapse of WTC2, because:

1) There was little or no jet fuel in the building.

2) The carpets and furniture were fire resistant.

3) Even if there was an adequate supply of readily combustible fuel
present, 56 minutes is not enough time to develop a fire intense
enough or large enough in extent to weaken the steel enough, given the
thermal mass of steel and concrete present (every floor had hundreds
of thousands of kg of steel and over one million kg of concrete).

Come now, the aircraft were carrying heavy fuel loads and in addition
there was a large diesel fuel in at least one of the buildings for the
back-up generators.

There are several videos around showing the impact of Flight 175 with
WTC2; check 'em out.
It's plain to see that, immediately upon impact, a misty cloud of fuel
forms on the opposite side of the building...and it then ignites into
a fireball that is big enough (assuming a lower flammability limit of
0.6% by volume) to account for approximately ALL of the 10,000 gallons
estimated by the government to have been on the plane at impact.


In fact, contrary to the conspiracy theorists arguments of "cover up"
there have been a number of studies published in peer reviewed
journals. I read one in either the Civil Engineering or Mechanical
Engineering Association's publication that was extremely detailed in
describing both the failures and the causes of the failures.

The article questioned both the design and construction of the Towers
and speculated about whether it would be possible to build a tower
that would be proof against another such incident.

Journals of this sort are read by a very large percentage of working
engineers and if there had been either faulty details or calculations
in the article I'm sure that someone, somewhere, would have commented
on it.

One of the things that seems so strange about the whole conspiracy
theory is that the majority of the people that subscribe to it are not
professional engineers and, quite simply, do not have enough technical
knowledge to evaluate the event.


Well, Bruce in Bangkok, when they ignore something like the
indisputably obvious fact that MOST of Flight 175's jet fuel burnt up
outside the building, and then go on to make claims that "the jet fuel-
fed fire reached 1000 degrees centigrade blah-blah-blah" (in a
remarkably short 56 minute time frame no less), with a thermal mass of
almost 2E6 kg present, I started asking questions.

And I've found it's more a matter of "human psychology", apparently,
than it is a matter of "technical knowledge".

Have you ever heard the saying: "A man that should call everything by
its right name would hardly pass
the street without being knocked down as a common enemy."?

Put simply, it's only strange because you are apparently unfamiliar
with human natu There are careers involved here; there is "group
think" involved here; there is an aversion to the notion that our own
government may be complicit involved here, etc.

For a recent notable example of this, look what happened to Dr. James
Watson, co-winner of the Nobel Prize for discovering the structure of
DNA and the man most responsible for the Human Genome Project.

Dr. Watson made the mistake of publicly stating that there are IQ
differences between races, and now finds himself forced to resign from
his lab. Universities and museums have also canceled his lectures, and
he is now being labeled a "racist". All this for merely stating what
he believes to be an obvious scientific truth, albeit a highly
politically incorrect one. Do you follow?

On Nov 4, 3:59 am, Bruce in Bangkok wrote:
On Sat, 03 Nov 2007 09:28:22 -0700, wrote:
On Nov 2, 8:28 pm, John Husvar wrote:
In article ,
pyotr filipivich wrote:

After a Computer crash and the demise of civilization, it was learned
"cncfixxer1" wrote on Fri, 02 Nov 2007 15:35:54
GMT in rec.crafts.metalworking :
Has to do with volume and speed of air ... the same as bellows that were
used in blacksmithing.

Years ago a neighbors house burned down and the metal beams actually melted
... not twisted but melted..
That was from just wood and air

Stainless steel grills are suppose to stand up to bbq fires. They
do, but not when the fire is augmented with coal and a forced draft.

It needn't even require forced draft. Some African blacksmiths use
charcoal fired forges made of tile pipe hanging from a tree limb or
another handy support.

The pipe has a grate and is open bottom to top with a hole in the side
for the smith to insert workpieces.

Just the natural draft from the heated air up the pipe drawing in cool
air at the bottom can keep the forge hot enough to burn/melt steel.

Way I figure it, the natural draft from the fires in the two main WTC
buildings was probably more than enough to generate enough heat to
weaken the floor trusses. When one gave way, everything above that
slammed into those floors and all of that pancaked into the lower floors.

No conspiracy needed, just lots of fuel and natural draft from the
chimney effect of a tall building with big holes in its sides.

Sorry, but there's not the slightest chance that fire contributed
meaningfully to the collapse of WTC2, because:

1) There was little or no jet fuel in the building.

2) The carpets and furniture were fire resistant.

3) Even if there was an adequate supply of readily combustible fuel
present, 56 minutes is not enough time to develop a fire intense
enough or large enough in extent to weaken the steel enough, given the
thermal mass of steel and concrete present (every floor had hundreds
of thousands of kg of steel and over one million kg of concrete).

Come now, the aircraft were carrying heavy fuel loads and in addition
there was a large diesel fuel in at least one of the buildings for the
back-up generators.

There are several videos around showing the impact of Flight 175 with
WTC2; check 'em out.
It's plain to see that, immediately upon impact, a misty cloud of fuel
forms on the opposite side of the building...and it then ignites into
a fireball that is big enough (assuming a lower flammability limit of
0.6% by volume) to account for approximately ALL of the 10,000 gallons
estimated by the government to have been on the plane at impact.


In fact, contrary to the conspiracy theorists arguments of "cover up"
there have been a number of studies published in peer reviewed
journals. I read one in either the Civil Engineering or Mechanical
Engineering Association's publication that was extremely detailed in
describing both the failures and the causes of the failures.

The article questioned both the design and construction of the Towers
and speculated about whether it would be possible to build a tower
that would be proof against another such incident.

Journals of this sort are read by a very large percentage of working
engineers and if there had been either faulty details or calculations
in the article I'm sure that someone, somewhere, would have commented
on it.

One of the things that seems so strange about the whole conspiracy
theory is that the majority of the people that subscribe to it are not
professional engineers and, quite simply, do not have enough technical
knowledge to evaluate the event.


Well, Bruce in Bangkok, when they ignore something like the
indisputably obvious fact that MOST of Flight 175's jet fuel burnt up
outside the building, and then go on to make claims that "the jet fuel-
fed fire reached 1000 degrees centigrade blah-blah-blah" (in a
remarkably short 56 minute time frame no less), with a thermal mass of
almost 2E6 kg present, I started asking questions.

And I've found it's more a matter of "human psychology", apparently,
than it is a matter of "technical knowledge".

Have you ever heard the saying: "A man that should call everything by
its right name would hardly pass
the street without being knocked down as a common enemy."?

Put simply, it's only strange because you are apparently unfamiliar
with human natu There are careers involved here; there is "group
think" involved here; there is an aversion to the notion that our own
government may be complicit involved here, etc.

For a recent notable example of this, look what happened to Dr. James
Watson, co-winner of the Nobel Prize for discovering the structure of
DNA and the man most responsible for the Human Genome Project.

Dr. Watson made the mistake of publicly stating that there are IQ
differences between races, and now finds himself forced to resign from
his lab. Universities and museums have also canceled his lectures, and
he is now being labeled a "racist". All this for merely stating what
he believes to be an obvious scientific truth, albeit a highly
politically incorrect one. Do you follow?

On Sun, 04 Nov 2007 03:31:03 -0800, wrote:



But unless the temperature is very high, it will not PROPAGATE, which
was most likely the case.

Sure it will, it just takes more to ignite. Given sufficient heat flux, it
will propagate. Flame spread is a series of ignitions. Given enough energy,
and oxygen, it will burn. Having done a number of cone calorimeter tests on
furniture foam, including that used in aircraft (and hundreds of flame
psread and ignition tests on wood), not only does it burn, it continues to
do so after ignition. The heat flux for flame spread will vary by
orientation, but some data points I could lay my hands on quickly:
V Babrauskas and Wetterlund did a number of cone calorimeter tests and
lateral flamse spread tests in the ASTM 1321 LIFT apparatus as part of the
Surofic fire test series. Fire retardent PU foam had a minimum ignition
flux of around 3KW/m2.Kevlar covered PU foam was better at around 13kW/m2 -
to be expected as the kevlar (or wool) retards the ignition of the
vapourising PU foam. Wool forms an insulating char layer, which is one
reason it is often used for auditorium seating. For more specific info on
furiture foam and ignition, see Chen's thesis in the University of
Canterbury.
More specifically on flame spread, babruaskas even provides nice pictures
of burning foam in the flame spread testing rig.
Babrauskas, V. Wetterlund I. Comparative data from LIFT and cone
calorimetertests on 6 products including flame flux measurements, Publ SP,
Sweden. SP report 1999:14.
If you really want to get into it, I suggest Babrauskas' book "the ignition
handbook" for some further light reading. About $200 well spent if you are
interested in the field.

I woudl also be surprised if the furnitreu and carpets
were especially fire resistant, unless it was required by the building
code. Given the sprinkler system, there isn't much point from a fire
engineering perspective.
There is PLENTY of other fuel (beside the jet fuel) in an office - paper,

Modern offices are not loaded with paper like they were years ago. And
the paper that is there is usually inside filing cabinets etc.; it's
certainly not "readily available".

You haven't seen my desk recently (mind you, neither have I...:-)


desks, wooden fittings, panelling, softboard ceiling tiles, etc. 3) Even if there was an adequate supply of readily combustible fuel
present, 56 minutes is not enough time to develop a fire intense
enough or large enough in extent to weaken the steel enough, given the
thermal mass of steel and concrete present (every floor had hundreds
of thousands of kg of steel and over one million kg of concrete).

Sure it is. The floors were supported on relatively lightweight trusses,
whcih have a lot of expeosed area (high surface to cross section ratio)-
this means it will heat up fast.

Not a chance. Too much thermal mass there. Way too much. You can't
selectively heat what you want without heating everything else in the
vicinity, e.g., concrete. Look up the Stefan-Boltzmann law. Hot
surfaces start radiating away huge amounts of power to the
surroundings...the power scales as T^4.

a 610UB will reach 500 deg C in around 9 minutes in a "standard" fire, at
which point it has around 20% of the original strecnght. Steel starts to
weaken around 300 deg C. If you want the exact figures, it will have to
wait until Monday when I am back at work.

I already looked it up. It losses about 10% at 300 degrees C. Nowhere
near enough, and it's doubtful the fire even reached that temp over
any appreciable area in the first place.

See below

More importanly for the WTC collapse was the connections of the trusses at
each end - to the central core and the vertical columns at the preimeter.
These failed (rather than the trusses) so theends failed in sear, so the
collapesed straight down - hence the pancake.

Well, IIRC, that's not what NIST is claiming. In fact they're claiming
an inferno of 1000 degrees centigrade, and that's pure nonsense.

A house fire will easily get to well over 800 deg C. Flashover is at around
600 deg C, which is when all combustibles in the room spontaneously ignite.
the head flux to the floor is around 20kW/m2 at that time. There is a well
known ad promoting fire safety showing the effect of a ciggie lighting a
sofa, curtains to flashover in a few minutes. That is a house, which has a
comparably lower fuel load than an office (circa 400MJ/m2 vs 800 MJ /m2
typical). There is no reason why the WTC would be much cooler.

The temperature of fires in buildings has been very well researched, as it
has a significant effect on the structure (duh!) and also the premature
failure of gypsum plasterboard. The initial research was started by
Margaret Law in the UK in the 1960s at BRE (IIRC), so it is nothing new. A
major early publication was from Marguesson (sp) in Sweden with a number of
real fire tests. Depending on the fuel load and openings, temperatures
ranged up to 1200 deg C.
There has been significant research into fires in commercial buildings,
given the huge market and money at stake. BHP, a major Australian steel
manufacturer did a huge number of tests in the 1980s. The Building Reserch
Establishment (BRE) in the UK built a 6 story steel office tower in an old
airship hanger at Cardington for a well known series of full scale fire
tests. A couple of friends were involved in them. These tests were fully
instrumented, so the temperatures of the members and at a number of points
around the building were recorded, and much of it has been published over
the years as it formed the basis for a lot of research and verification of
theories and methods.
An office mockup test at Cardington gave an average temperature of 900 deg
and a maximum of 1200 deg C. The unprotected steel reached 813-1150 deg C,
which is PLENTY hot enough to turn it into cooked spagetti.
http://guardian.150m.com/fire/small/SCI.htm (about halfway down the page)
I could probably get the actual test data if I asked for it.

A well known accidental fire was Broadgate in the UK. It was a conventional
office building with steel framing, concrete slabs on steel beams. The
building was under construction and hadn't had the fire rating applied. A
fire broke out in a site shed, and was enough to severely deform the beams
and columns. The building didn't collapse due to moment redistrbution of
the load, thanks to the design of the building, with welded and pinned
joints and multiple columns. The WTC was different, with the central core
and perimeter columns, it relied on the connections at each end of the
trusses. When either the connections failed, or the trusses twisted so the
load was no longer correctly supported, it was all over.
The temperature was estimated to be around 1100 deg C for the Broadgate
fire.
More info on real fires and temperatures at:
http://www.modernsteel.com/Uploads/I...07_01_fire.pdf
http://books.google.com/books?id=0mp...uyD14ZyBf1XdeE
I suggest Andy Buchanan's fine book
http://www.amazon.com/Structural-Des...4256734&sr=8-1


A key difference between the WTC and natural fires was the development of
the fire. In a normal fire, it will start at a single point of ignition -
say an overheated computer, and spread through the floor as neighboring
items ignite until the upper layer temperature is enough to cause radiation
on the floor to induce flashover. In this case, a significant amount of jet
fuel started fires everywhere. Even if some jet fuel was burnt outside the
building, not every drop was burnt outside, and the radiation of the huge
fireball would have been enough to start fires anyway. The multiple fire
starts are the reason why the fire reached a peak sooner and hotter than
might have been the case in an accidental fire.

Next time you have a conspiracy theory, try to at least make it plausible.
Now, a bunch of US politicians cynically using the event to promote a
political agenda and introduce new catch-all laws and invade the Middle
East - that is a plausible conspiracy theory.
Geoff

On Nov 5, 5:02 am, Geoff wrote:
On Sun, 04 Nov 2007 03:31:03 -0800, wrote:

I note that you conveniently snipped out my point about the jet fuel
burning outside the building.


But unless the temperature is very high, it will not PROPAGATE, which
was most likely the case.

Sure it will, it just takes more to ignite. Given sufficient heat flux, it
will propagate. Flame spread is a series of ignitions. Given enough energy,
and oxygen, it will burn.

And given enough energy and confinement, deuterium nuclei will fuse. I
guess the point is, given enough of anything, anything's possible.


Having done a number of cone calorimeter tests on
furniture foam, including that used in aircraft (and hundreds of flame
psread and ignition tests on wood), not only does it burn, it continues to
do so after ignition. The heat flux for flame spread will vary by
orientation, but some data points I could lay my hands on quickly:
V Babrauskas and Wetterlund did a number of cone calorimeter tests and
lateral flamse spread tests in the ASTM 1321 LIFT apparatus as part of the
Surofic fire test series. Fire retardent PU foam had a minimum ignition
flux of around 3KW/m2.

ROTFL! That's 0.3 W/cm^2...that's nonsense.

Kevlar covered PU foam was better at around 13kW/m2 -
to be expected as the kevlar (or wool) retards the ignition of the
vapourising PU foam. Wool forms an insulating char layer, which is one
reason it is often used for auditorium seating. For more specific info on
furiture foam and ignition, see Chen's thesis in the University of
Canterbury.
More specifically on flame spread, babruaskas even provides nice pictures
of burning foam in the flame spread testing rig.
Babrauskas, V. Wetterlund I. Comparative data from LIFT and cone
calorimetertests on 6 products including flame flux measurements, Publ SP,
Sweden. SP report 1999:14.
If you really want to get into it, I suggest Babrauskas' book "the ignition
handbook" for some further light reading. About $200 well spent if you are
interested in the field.

I suggest you buy a basic physics book and learn about things like
power and energy; then, when you have a grasp of the basic underlying
physics, you can move along to some specific applications.



I woudl also be surprised if the furnitreu and carpets
were especially fire resistant, unless it was required by the building
code. Given the sprinkler system, there isn't much point from a fire
engineering perspective.
There is PLENTY of other fuel (beside the jet fuel) in an office - paper,

Modern offices are not loaded with paper like they were years ago. And
the paper that is there is usually inside filing cabinets etc.; it's
certainly not "readily available".

You haven't seen my desk recently (mind you, neither have I...:-)

Ok, so you may be a slob, but the point is that office buildings
generally don't have anywhere near the paper laying around that they
had 10 to 15 years ago or so.




desks, wooden fittings, panelling, softboard ceiling tiles, etc. 3) Even if there was an adequate supply of readily combustible fuel
present, 56 minutes is not enough time to develop a fire intense
enough or large enough in extent to weaken the steel enough, given the
thermal mass of steel and concrete present (every floor had hundreds
of thousands of kg of steel and over one million kg of concrete).

Sure it is. The floors were supported on relatively lightweight trusses,
whcih have a lot of expeosed area (high surface to cross section ratio)-
this means it will heat up fast.

Not a chance. Too much thermal mass there. Way too much. You can't
selectively heat what you want without heating everything else in the
vicinity, e.g., concrete. Look up the Stefan-Boltzmann law. Hot
surfaces start radiating away huge amounts of power to the
surroundings...the power scales as T^4.

a 610UB will reach 500 deg C in around 9 minutes in a "standard" fire, at
which point it has around 20% of the original strecnght.

I think for the steel used in the WTC towers the number was about 700
degrees centigrade for 80% reduction in strength.

In any case, the WTC towers had several hundred thousand kg of steel
and over a million kg of concrete per floor. Your uninformed pedantry
and hand-waving notwithstanding, in order to raise the temperature of
this kind of thermal mass to 700 degrees centigrade, you have to
release over 3E12 J of energy (and this is neglecting losses - a
ridiculously generous constraint). To release this kind of energy in
56 minutes would require a specially designed apparatus, e.g., about a
dozen blowers the size of jet engines, to feed enough air to the
fire.

Steel starts to
weaken around 300 deg C. If you want the exact figures, it will have to
wait until Monday when I am back at work.

I already looked it up. It losses about 10% at 300 degrees C. Nowhere
near enough, and it's doubtful the fire even reached that temp over
any appreciable area in the first place.

See below

More importanly for the WTC collapse was the connections of the trusses at
each end - to the central core and the vertical columns at the preimeter.
These failed (rather than the trusses) so theends failed in sear, so the
collapesed straight down - hence the pancake.

Well, IIRC, that's not what NIST is claiming. In fact they're claiming
an inferno of 1000 degrees centigrade, and that's pure nonsense.

A house fire will easily get to well over 800 deg C. Flashover is at around
600 deg C, which is when all combustibles in the room spontaneously ignite.

You've got a steel and concrete building with approximately 2E6 kg of
thermal mass per floor, little or no "readily available" fuel, and
little airflow.

You cannot reach temperatures anywhere near the 600 to 700 degree
centigrade range in 56 minutes under these conditions. You'd have to
rig up some kind of high tech blast furnace.

the head flux to the floor is around 20kW/m2 at that time. There is a well
known ad promoting fire safety showing the effect of a ciggie lighting a
sofa, curtains to flashover in a few minutes. That is a house, which has a
comparably lower fuel load than an office (circa 400MJ/m2 vs 800 MJ /m2
typical). There is no reason why the WTC would be much cooler.

The temperature of fires in buildings has been very well researched, as it
has a significant effect on the structure (duh!) and also the premature
failure of gypsum plasterboard. The initial research was started by
Margaret Law in the UK in the 1960s at BRE (IIRC), so it is nothing new. A
major early publication was from Marguesson (sp) in Sweden with a number of
real fire tests. Depending on the fuel load and openings, temperatures
ranged up to 1200 deg C.

Sorry but you won't do it in 56 minutes, at least not over any kind of
an area.

There has been significant research into fires in commercial buildings,
given the huge market and money at stake. BHP, a major Australian steel
manufacturer did a huge number of tests in the 1980s. The Building Reserch
Establishment (BRE) in the UK built a 6 story steel office tower in an old
airship hanger at Cardington for a well known series of full scale fire
tests. A couple of friends were involved in them. These tests were fully
instrumented, so the temperatures of the members and at a number of points
around the building were recorded, and much of it has been published over
the years as it formed the basis for a lot of research and verification of
theories and methods.
An office mockup test at Cardington gave an average temperature of 900 deg
and a maximum of 1200 deg C. The unprotected steel reached 813-1150 deg C,
which is PLENTY hot enough to turn it into cooked spagetti.http://guardian.150m.com/fire/small/SCI.htm(about halfway down the page)
I could probably get the actual test data if I asked for it.

Sorry but you won't do it in 56 minutes.


A well known accidental fire was Broadgate in the UK. It was a conventional
office building with steel framing, concrete slabs on steel beams. The
building was under construction and hadn't had the fire rating applied. A
fire broke out in a site shed, and was enough to severely deform the beams
and columns. The building didn't collapse due to moment redistrbution of
the load, thanks to the design of the building, with welded and pinned
joints and multiple columns. The WTC was different, with the central core
and perimeter columns, it relied on the connections at each end of the
trusses. When either the connections failed, or the trusses twisted so the
load was no longer correctly supported, it was all over.
The temperature was estimated to be around 1100 deg C for the Broadgate
fire.
More info on real fires and temperatures at:http://www.modernsteel.com/Uploads/I...pg=PA67&dq=bro...
I suggest Andy Buchanan's fine bookhttp://www.amazon.com/Structural-Design-Safety-Andrew-Buchanan/dp/047...

A key difference between the WTC and natural fires was the development of
the fire. In a normal fire, it will start at a single point of ignition -
say an overheated computer, and spread through the floor as neighboring
items ignite until the upper layer temperature is enough to cause radiation
on the floor to induce flashover. In this case, a significant amount of jet
fuel started fires everywhere. Even if some jet fuel was burnt outside the
building, not every drop was burnt outside, and the radiation of the huge
fireball would have been enough to start fires anyway.

Bull****. It's plain to see *from simple calculations* that MOST if
not ALL of the jet fuel went up in a cloud outside WTC2.
The size of the fireball basically accounts for ALL the fuel...if any
was left inside it was probably an insignificant amount.

But the fact is it wouldn't have mattered if you filled the whole
****ing building up with the hydrocarbon fuel of your choice, you
simply cannot burn enough fuel in 56 minutes time (without a specially
constructed apparatus) to heat 2E6 kg of construction materials up to
600 - 700 degrees centigrade.


The multiple fire
starts are the reason why the fire reached a peak sooner and hotter than
might have been the case in an accidental fire.

Bull****.


Next time you have a conspiracy theory, try to at least make it plausible.

Next time you try to decide what's "plausible", try to get a grasp of
basic physics first.

On Nov 5, 1:45 pm, wrote:


Next time you try to decide what's "plausible", try to get a grasp of
basic physics first.

The fact is that the building did burn and collapse. There is no
evidence that any effort was made to demolish the building. Only
theories. And with the amount of explosives that would have been
involved, it is extremely unlikely that no one would have noticed the
work being done to demolish the building. So it is pretty obvious to
me that 1. An airplane did crash into the building. and 2. that the
building did burn and collapse. So you need to rethink your theories
to agree with the facts.

You claim that most of the fuel burned outside the building. Since
the airplane crashed into the building and penetrated the outer
structure, it seems obvious to the most casual observer that much of
the fuel was inside the building.

I know Geoff's credentials. Please let us know about your education
and experience.


Dan


Dan

On Nov 5, 11:45 am, " wrote:
On Nov 5, 1:45 pm, wrote:



Next time you try to decide what's "plausible", try to get a grasp of
basic physics first.

The fact is that the building did burn and collapse.

But the *question* is: Did the fire significantly contribute to the
collapse or not?

There is no
evidence that any effort was made to demolish the building.

On the contrary, the probable fact that the plane impact and
subsequent scattered, smothered, short burning fires were insufficient
to cause the collapse that was witnessed, constitutes prima facie
evidence that the building was rigged for demolition beforehand.

Only
theories.

Well sure. Unfortunately, unless and until we can have some semblance
of a real investigation, all we have are theories; the least likely of
which being the conspiracy theory proffered by the government.

And with the amount of explosives that would have been
involved, it is extremely unlikely that no one would have noticed the
work being done to demolish the building.

Why do you say that? As I understand it, there were several
conspicuous "power-downs" of the towers shortly before 9/11. These
would have provided ample opportunity to rig the buildings.
http://www.serendipity.li/wot/forbes01.htm


So it is pretty obvious to
me that 1. An airplane did crash into the building.

Well I would think so.


and 2. that the
building did burn and collapse.

Yes, it did burn (to some extent) and it did collapse.

So you need to rethink your theories
to agree with the facts.

Most prominent among "the facts" as I know them, is the fact that you
very likely cannot develop a fire hot enough, nor large enough in
extent, to weaken the steel in question, in a mere 56 minutes time
frame. IOW, taking one floor of a WTC tower as a model, you would need
an airflow of about 6E5 CFM, for each of those 56 minutes, to burn
enough fuel to raise the temperature of one floor's worth of
construction materials to 700 degrees centigrade. And that doesn't
even include losses; if you include probable losses by convection,
conduction and radiation, the numbers get even more ridiculous.

My theory comports with this fact.


You claim that most of the fuel burned outside the building.

Of course I do, since, given the lower flammability limit of jet fuel
in air (0.6% by volume), and, given the video evidence showing a
fireball whose approximate dimensions at ignition can be gauged by
visual comparison with the known size of the adjacent WTC building,
it's plain to see that most of the 10,000 gallons of fuel said to be
on-board at impact would have burnt up in that fireball.

Since
the airplane crashed into the building and penetrated the outer
structure, it seems obvious to the most casual observer that much of
the fuel was inside the building.

Well then the casual observer should go to youtube and view the
several available videos of Flight 175's impact, from several angles,
that clearly show the fuel cloud develop (on the outside of the
building) and ignite into a fireball of about 75 feet in diameter; and
then the casual observer can carry out the simple calculation implicit
in my above statement and decide for themselves how much of that
estimated 10,000 gallons might have remained in the building.

On Nov 5, 7:44 pm, wrote:

Why do you say that? As I understand it, there were several
conspicuous "power-downs" of the towers shortly before 9/11. These
would have provided ample opportunity to rig the buildings.http://www.serendipity.li/wot/forbes01.htm


Most prominent among "the facts" as I know them, is the fact that you
very likely cannot develop a fire hot enough, nor large enough in
extent, to weaken the steel in question, in a mere 56 minutes time
frame. IOW, taking one floor of a WTC tower as a model, you would need
an airflow of about 6E5 CFM, for each of those 56 minutes, to burn
enough fuel to raise the temperature of one floor's worth of
construction materials to 700 degrees centigrade. And that doesn't
even include losses; if you include probable losses by convection,
conduction and radiation, the numbers get even more ridiculous.

My theory comports with this fact.



Honest we are laughing with you, not at you.

Dan

On Mon, 05 Nov 2007 05:45:06 -0800, wrote:

On Nov 5, 5:02 am, Geoff wrote:
On Sun, 04 Nov 2007 03:31:03 -0800, wrote:

I note that you conveniently snipped out my point about the jet fuel
burning outside the building.


But unless the temperature is very high, it will not PROPAGATE, which
was most likely the case.

Sure it will, it just takes more to ignite. Given sufficient heat flux, it
will propagate. Flame spread is a series of ignitions. Given enough energy,
and oxygen, it will burn.

And given enough energy and confinement, deuterium nuclei will fuse. I
guess the point is, given enough of anything, anything's possible.


Having done a number of cone calorimeter tests on
furniture foam, including that used in aircraft (and hundreds of flame
psread and ignition tests on wood), not only does it burn, it continues to
do so after ignition. The heat flux for flame spread will vary by
orientation, but some data points I could lay my hands on quickly:
V Babrauskas and Wetterlund did a number of cone calorimeter tests and
lateral flamse spread tests in the ASTM 1321 LIFT apparatus as part of the
Surofic fire test series. Fire retardent PU foam had a minimum ignition
flux of around 3KW/m2.

ROTFL! That's 0.3 W/cm^2...that's nonsense.

The minimum ignition flux is the flux which will cause (piloted in this
case) ignition over a long time period. The theory is rather more
complicated than can be explained on Usenet - google for Jannsen's theory
of ignition.

Kevlar covered PU foam was better at around 13kW/m2 -
to be expected as the kevlar (or wool) retards the ignition of the
vapourising PU foam. Wool forms an insulating char layer, which is one
reason it is often used for auditorium seating. For more specific info on
furiture foam and ignition, see Chen's thesis in the University of
Canterbury.
More specifically on flame spread, babruaskas even provides nice pictures
of burning foam in the flame spread testing rig.
Babrauskas, V. Wetterlund I. Comparative data from LIFT and cone
calorimetertests on 6 products including flame flux measurements, Publ SP,
Sweden. SP report 1999:14.
If you really want to get into it, I suggest Babrauskas' book "the ignition
handbook" for some further light reading. About $200 well spent if you are
interested in the field.

I suggest you buy a basic physics book and learn about things like
power and energy; then, when you have a grasp of the basic underlying
physics, you can move along to some specific applications.

How about a Masters in Fire Engineering, with a thesis on ignition and
flame spread, and a published papers in peer reviewed journals, and
coauthor of a presentation and paper at an international conference?
I think I know something about burning buildings... I deal with this stuff
every day, and people pay me to do it.

Geoff

On Mon, 05 Nov 2007 05:45:06 -0800, wrote:

On Nov 5, 5:02 am, Geoff wrote:
On Sun, 04 Nov 2007 03:31:03 -0800, wrote:

I note that you conveniently snipped out my point about the jet fuel
burning outside the building.


But unless the temperature is very high, it will not PROPAGATE, which
was most likely the case.

Sure it will, it just takes more to ignite. Given sufficient heat flux, it
will propagate. Flame spread is a series of ignitions. Given enough energy,
and oxygen, it will burn.

And given enough energy and confinement, deuterium nuclei will fuse. I
guess the point is, given enough of anything, anything's possible.


Having done a number of cone calorimeter tests on
furniture foam, including that used in aircraft (and hundreds of flame
psread and ignition tests on wood), not only does it burn, it continues to
do so after ignition. The heat flux for flame spread will vary by
orientation, but some data points I could lay my hands on quickly:
V Babrauskas and Wetterlund did a number of cone calorimeter tests and
lateral flamse spread tests in the ASTM 1321 LIFT apparatus as part of the
Surofic fire test series. Fire retardent PU foam had a minimum ignition
flux of around 3KW/m2.

ROTFL! That's 0.3 W/cm^2...that's nonsense.

Kevlar covered PU foam was better at around 13kW/m2 -
to be expected as the kevlar (or wool) retards the ignition of the
vapourising PU foam. Wool forms an insulating char layer, which is one
reason it is often used for auditorium seating. For more specific info on
furiture foam and ignition, see Chen's thesis in the University of
Canterbury.
More specifically on flame spread, babruaskas even provides nice pictures
of burning foam in the flame spread testing rig.
Babrauskas, V. Wetterlund I. Comparative data from LIFT and cone
calorimetertests on 6 products including flame flux measurements, Publ SP,
Sweden. SP report 1999:14.
If you really want to get into it, I suggest Babrauskas' book "the ignition
handbook" for some further light reading. About $200 well spent if you are
interested in the field.

I suggest you buy a basic physics book and learn about things like
power and energy; then, when you have a grasp of the basic underlying
physics, you can move along to some specific applications.



I woudl also be surprised if the furnitreu and carpets
were especially fire resistant, unless it was required by the building
code. Given the sprinkler system, there isn't much point from a fire
engineering perspective.
There is PLENTY of other fuel (beside the jet fuel) in an office - paper,

Modern offices are not loaded with paper like they were years ago. And
the paper that is there is usually inside filing cabinets etc.; it's
certainly not "readily available".

You haven't seen my desk recently (mind you, neither have I...:-)

Ok, so you may be a slob, but the point is that office buildings
generally don't have anywhere near the paper laying around that they
had 10 to 15 years ago or so.




desks, wooden fittings, panelling, softboard ceiling tiles, etc. 3) Even if there was an adequate supply of readily combustible fuel
present, 56 minutes is not enough time to develop a fire intense
enough or large enough in extent to weaken the steel enough, given the
thermal mass of steel and concrete present (every floor had hundreds
of thousands of kg of steel and over one million kg of concrete).

Sure it is. The floors were supported on relatively lightweight trusses,
whcih have a lot of expeosed area (high surface to cross section ratio)-
this means it will heat up fast.

Not a chance. Too much thermal mass there. Way too much. You can't
selectively heat what you want without heating everything else in the
vicinity, e.g., concrete. Look up the Stefan-Boltzmann law. Hot
surfaces start radiating away huge amounts of power to the
surroundings...the power scales as T^4.

a 610UB will reach 500 deg C in around 9 minutes in a "standard" fire, at
which point it has around 20% of the original strecnght.

I think for the steel used in the WTC towers the number was about 700
degrees centigrade for 80% reduction in strength.

In any case, the WTC towers had several hundred thousand kg of steel
and over a million kg of concrete per floor. Your uninformed pedantry
and hand-waving notwithstanding, in order to raise the temperature of
this kind of thermal mass to 700 degrees centigrade, you have to
release over 3E12 J of energy (and this is neglecting losses - a
ridiculously generous constraint). To release this kind of energy in
56 minutes would require a specially designed apparatus, e.g., about a
dozen blowers the size of jet engines, to feed enough air to the
fire.

Steel starts to
weaken around 300 deg C. If you want the exact figures, it will have to
wait until Monday when I am back at work.

I already looked it up. It losses about 10% at 300 degrees C. Nowhere
near enough, and it's doubtful the fire even reached that temp over
any appreciable area in the first place.

See below

More importanly for the WTC collapse was the connections of the trusses at
each end - to the central core and the vertical columns at the preimeter.
These failed (rather than the trusses) so theends failed in sear, so the
collapesed straight down - hence the pancake.

Well, IIRC, that's not what NIST is claiming. In fact they're claiming
an inferno of 1000 degrees centigrade, and that's pure nonsense.

A house fire will easily get to well over 800 deg C. Flashover is at around
600 deg C, which is when all combustibles in the room spontaneously ignite.

You've got a steel and concrete building with approximately 2E6 kg of
thermal mass per floor, little or no "readily available" fuel, and
little airflow.

You cannot reach temperatures anywhere near the 600 to 700 degree
centigrade range in 56 minutes under these conditions. You'd have to
rig up some kind of high tech blast furnace.

the head flux to the floor is around 20kW/m2 at that time. There is a well
known ad promoting fire safety showing the effect of a ciggie lighting a
sofa, curtains to flashover in a few minutes. That is a house, which has a
comparably lower fuel load than an office (circa 400MJ/m2 vs 800 MJ /m2
typical). There is no reason why the WTC would be much cooler.

The temperature of fires in buildings has been very well researched, as it
has a significant effect on the structure (duh!) and also the premature
failure of gypsum plasterboard. The initial research was started by
Margaret Law in the UK in the 1960s at BRE (IIRC), so it is nothing new. A
major early publication was from Marguesson (sp) in Sweden with a number of
real fire tests. Depending on the fuel load and openings, temperatures
ranged up to 1200 deg C.

Sorry but you won't do it in 56 minutes, at least not over any kind of
an area.

There has been significant research into fires in commercial buildings,
given the huge market and money at stake. BHP, a major Australian steel
manufacturer did a huge number of tests in the 1980s. The Building Reserch
Establishment (BRE) in the UK built a 6 story steel office tower in an old
airship hanger at Cardington for a well known series of full scale fire
tests. A couple of friends were involved in them. These tests were fully
instrumented, so the temperatures of the members and at a number of points
around the building were recorded, and much of it has been published over
the years as it formed the basis for a lot of research and verification of
theories and methods.
An office mockup test at Cardington gave an average temperature of 900 deg
and a maximum of 1200 deg C. The unprotected steel reached 813-1150 deg C,
which is PLENTY hot enough to turn it into cooked spagetti.http://guardian.150m.com/fire/small/SCI.htm(about halfway down the page)
I could probably get the actual test data if I asked for it.

Sorry but you won't do it in 56 minutes.
Wanna bet? Plenty of scientific evidence says otherwise. The WTC fires were
much more severe any conventional fire for a building of the type =
multiple starts, much extra fuel, no suppression, etc.


A well known accidental fire was Broadgate in the UK. It was a conventional
office building with steel framing, concrete slabs on steel beams. The
building was under construction and hadn't had the fire rating applied. A
fire broke out in a site shed, and was enough to severely deform the beams
and columns. The building didn't collapse due to moment redistrbution of
the load, thanks to the design of the building, with welded and pinned
joints and multiple columns. The WTC was different, with the central core
and perimeter columns, it relied on the connections at each end of the
trusses. When either the connections failed, or the trusses twisted so the
load was no longer correctly supported, it was all over.
The temperature was estimated to be around 1100 deg C for the Broadgate
fire.
More info on real fires and temperatures at:http://www.modernsteel.com/Uploads/I...pg=PA67&dq=bro...
I suggest Andy Buchanan's fine bookhttp://www.amazon.com/Structural-Design-Safety-Andrew-Buchanan/dp/047...

A key difference between the WTC and natural fires was the development of
the fire. In a normal fire, it will start at a single point of ignition -
say an overheated computer, and spread through the floor as neighboring
items ignite until the upper layer temperature is enough to cause radiation
on the floor to induce flashover. In this case, a significant amount of jet
fuel started fires everywhere. Even if some jet fuel was burnt outside the
building, not every drop was burnt outside, and the radiation of the huge
fireball would have been enough to start fires anyway.

Bull****. It's plain to see *from simple calculations* that MOST if
not ALL of the jet fuel went up in a cloud outside WTC2.
The size of the fireball basically accounts for ALL the fuel...if any
was left inside it was probably an insignificant amount.

But the fact is it wouldn't have mattered if you filled the whole
****ing building up with the hydrocarbon fuel of your choice, you
simply cannot burn enough fuel in 56 minutes time (without a specially
constructed apparatus) to heat 2E6 kg of construction materials up to
600 - 700 degrees centigrade.

You don't have to heat the whole building up, only the important bits. That
is why fire protection is added to steel beams. it isn't to make some
applicator companies rich you know. If it wasn't necessary, it wouldn't be
done.
If the connections fail or the trusses deform in the fire room, then they
will collapse. The load will be transferred to other members, and hopefully
the whole lot will stay up, although the floor might sag and everything
bends a bit. Take out half the structure when half the supporting structure
is demolished by a plane, add lightweight trusses that can't take an
eccentric load due to the missing supports so they twist,etc, and it is all
over.
By definition the insulation criteria for fire walls means the mean
temperature on the cold side of a fire wall is less than 140 deg C (180
maximum at any point), yet the room or furnace on the other side can be
over 1000 deg C. And yes, I have seen this very event and have photos to
prove it. It was a plasterboard wall in the testing furnace at BRANZ. You
are right - it would be impossible to heat the entire building up,
unfortunately you don't have to. If you did, you wouldn't need to do have
any fire protection at all.

The multiple fire
starts are the reason why the fire reached a peak sooner and hotter than
might have been the case in an accidental fire.

Bull****.

Accidental fires grow exponentially. Typical upholstered furniture fire
growth is fast - heat release rate around 0.466*t^2 where t = seconds, HRR
will reach 1MW in around 150 seconds. A typical 3 seater couch is around
3-3.5MW peak HRR - it is like having a can of petrol in your living room.
With multiple ignitions you don't have that growth , or and incipient
smouldering. I have also been inside a house on fire, and outside at
flashover on several fires. It takes no great science to understand fires
are hot when you have been up close and personal to them or seen the
aftermath.
G

On Nov 6, 3:51 am, Geoff wrote:
On Mon, 05 Nov 2007 05:45:06 -0800, wrote:
On Nov 5, 5:02 am, Geoff wrote:
On Sun, 04 Nov 2007 03:31:03 -0800, wrote:


snip

An office mockup test at Cardington gave an average temperature of 900 deg
and a maximum of 1200 deg C. The unprotected steel reached 813-1150 deg C,
which is PLENTY hot enough to turn it into cooked spagetti.http://guardian.150m.com/fire/small/...m(abouthalfway down the page)
I could probably get the actual test data if I asked for it.

Sorry but you won't do it in 56 minutes.

Wanna bet?

Yep.

Plenty of scientific evidence says otherwise.

Please point it out. What evidence is there that WTC2 reached
temperatures of, say, even 500 degrees C, over any appreciable area.

The WTC fires were
much more severe any conventional fire for a building of the type =
multiple starts, much extra fuel, no suppression, etc.

Other buildings have burnt much longer, e.g., 18 hours, in fires that
were indisputably larger in extent and obviously much more intense
than anything WTC2 could have experienced, yet they never collapsed.

http://web.archive.org/web/200402160...n/meridian.htm




A well known accidental fire was Broadgate in the UK. It was a conventional
office building with steel framing, concrete slabs on steel beams. The
building was under construction and hadn't had the fire rating applied. A
fire broke out in a site shed, and was enough to severely deform the beams
and columns. The building didn't collapse due to moment redistrbution of
the load, thanks to the design of the building, with welded and pinned
joints and multiple columns. The WTC was different, with the central core
and perimeter columns, it relied on the connections at each end of the
trusses. When either the connections failed, or the trusses twisted so the
load was no longer correctly supported, it was all over.
The temperature was estimated to be around 1100 deg C for the Broadgate
fire.
More info on real fires and temperatures at:http://www.modernsteel.com/Uploads/I...7_01_fire.pdfh......
I suggest Andy Buchanan's fine bookhttp://www.amazon.com/Structural-Design-Safety-Andrew-Buchanan/dp/047...

A key difference between the WTC and natural fires was the development of
the fire. In a normal fire, it will start at a single point of ignition -
say an overheated computer, and spread through the floor as neighboring
items ignite until the upper layer temperature is enough to cause radiation
on the floor to induce flashover. In this case, a significant amount of jet
fuel started fires everywhere. Even if some jet fuel was burnt outside the
building, not every drop was burnt outside, and the radiation of the huge
fireball would have been enough to start fires anyway.

Even if "SOME" burnt outside the building? Well the videos are
available on youtube. The videos speak for themselves. Apparently
you've got it backwards: if SOME actually burnt inside the building
(in the case of WTC2 at least) it wasn't much.

IIRC, NIST did their simulations assuming something like 40% burnt in
the building, and as I recall, they never explained how they arrived
at that figure...and to the extent they're wrong about important
initial conditions, their whole simulation is wrong.


Bull****. It's plain to see *from simple calculations* that MOST if
not ALL of the jet fuel went up in a cloud outside WTC2.
The size of the fireball basically accounts for ALL the fuel...if any
was left inside it was probably an insignificant amount.

But the fact is it wouldn't have mattered if you filled the whole
****ing building up with the hydrocarbon fuel of your choice, you
simply cannot burn enough fuel in 56 minutes time (without a specially
constructed apparatus) to heat 2E6 kg of construction materials up to
600 - 700 degrees centigrade.

You don't have to heat the whole building up, only the important bits.

Not if you're using judiciously placed thermite and/or explosives, you
don't. If you're going to depend on randomly scattered fires then you
would generally have to, no? Unless you're going to claim that somehow
by magic, the fire/heat only went where it needed to go to cause
collapse? Last time I cooked a pie in the oven, I had to waste energy
heating the inside walls of the oven and even the room itself, to a
certain extent. If you've found a way to only heat what you want, what
are you doing working? Why aren't you out cruising the Caribbean on
your yacht, for example?

That
is why fire protection is added to steel beams. it isn't to make some
applicator companies rich you know. If it wasn't necessary, it wouldn't be
done.

In what sense is it deemed "necessary" and how do *you* personally
know it's "necessary"?

If the connections fail or the trusses deform in the fire room, then they
will collapse. The load will be transferred to other members, and hopefully
the whole lot will stay up, although the floor might sag and everything
bends a bit. Take out half the structure when half the supporting structure
is demolished by a plane, add lightweight trusses that can't take an
eccentric load due to the missing supports so they twist,etc, and it is all
over.
By definition the insulation criteria for fire walls means the mean
temperature on the cold side of a fire wall is less than 140 deg C (180
maximum at any point), yet the room or furnace on the other side can be
over 1000 deg C. And yes, I have seen this very event and have photos to
prove it. It was a plasterboard wall in the testing furnace at BRANZ. You
are right - it would be impossible to heat the entire building up,
unfortunately you don't have to. If you did, you wouldn't need to do have
any fire protection at all.

Well how effective will insulation be after a fire burns for many
hours? The "One Meridian Plaza" fire burnt for 18 hours and involved
many floors, seven of those hours without any firefighting efforts at
all. According to "Simpson Gumpertz and Heger", "the twelve-alarm fire
burned for 18 hours. The extreme heat caused window glass and frames
to melt and concrete floor slabs and steel beams to buckle and sag
dramatically."

Let's see, if the steel beams "buckled and sagged dramatically", then
either the beams weren't insulated or the insulation wasn't much good,
no? Yet the building still didn't collapse.


The multiple fire
starts are the reason why the fire reached a peak sooner and hotter than
might have been the case in an accidental fire.

Bull****.

Accidental fires grow exponentially. Typical upholstered furniture fire
growth is fast - heat release rate around 0.466*t^2 where t = seconds, HRR
will reach 1MW in around 150 seconds. A typical 3 seater couch is around
3-3.5MW peak HRR - it is like having a can of petrol in your living room.
With multiple ignitions you don't have that growth , or and incipient
smouldering. I have also been inside a house on fire, and outside at
flashover on several fires. It takes no great science to understand fires
are hot when you have been up close and personal to them or seen the
aftermath.
G

Well, yes, assuming you have enough oxygen available. You can't get MW
of heat for any length of time without lots of airflow. You may have
adequate air near a broken widow or hole in the wall, but what about
everywhere else? You can't do it in 56 minutes.

On Nov 6, 3:51 am, Geoff wrote:
On Mon, 05 Nov 2007 05:45:06 -0800, wrote:
On Nov 5, 5:02 am, Geoff wrote:
On Sun, 04 Nov 2007 03:31:03 -0800, wrote:

I note that you conveniently snipped out my point about the jet fuel
burning outside the building.

But unless the temperature is very high, it will not PROPAGATE, which
was most likely the case.

Sure it will, it just takes more to ignite. Given sufficient heat flux, it
will propagate. Flame spread is a series of ignitions. Given enough energy,
and oxygen, it will burn.

And given enough energy and confinement, deuterium nuclei will fuse. I
guess the point is, given enough of anything, anything's possible.

Having done a number of cone calorimeter tests on
furniture foam, including that used in aircraft (and hundreds of flame
psread and ignition tests on wood), not only does it burn, it continues to
do so after ignition. The heat flux for flame spread will vary by
orientation, but some data points I could lay my hands on quickly:
V Babrauskas and Wetterlund did a number of cone calorimeter tests and
lateral flamse spread tests in the ASTM 1321 LIFT apparatus as part of the
Surofic fire test series. Fire retardent PU foam had a minimum ignition
flux of around 3KW/m2.

ROTFL! That's 0.3 W/cm^2...that's nonsense.

Kevlar covered PU foam was better at around 13kW/m2 -
to be expected as the kevlar (or wool) retards the ignition of the
vapourising PU foam. Wool forms an insulating char layer, which is one
reason it is often used for auditorium seating. For more specific info on
furiture foam and ignition, see Chen's thesis in the University of
Canterbury.
More specifically on flame spread, babruaskas even provides nice pictures
of burning foam in the flame spread testing rig.
Babrauskas, V. Wetterlund I. Comparative data from LIFT and cone
calorimetertests on 6 products including flame flux measurements, Publ SP,
Sweden. SP report 1999:14.
If you really want to get into it, I suggest Babrauskas' book "the ignition
handbook" for some further light reading. About $200 well spent if you are
interested in the field.

I suggest you buy a basic physics book and learn about things like
power and energy; then, when you have a grasp of the basic underlying
physics, you can move along to some specific applications.

I woudl also be surprised if the furnitreu and carpets
were especially fire resistant, unless it was required by the building
code. Given the sprinkler system, there isn't much point from a fire
engineering perspective.
There is PLENTY of other fuel (beside the jet fuel) in an office - paper,

Modern offices are not loaded with paper like they were years ago. And
the paper that is there is usually inside filing cabinets etc.; it's
certainly not "readily available".

You haven't seen my desk recently (mind you, neither have I...:-)

Ok, so you may be a slob, but the point is that office buildings
generally don't have anywhere near the paper laying around that they
had 10 to 15 years ago or so.

desks, wooden fittings, panelling, softboard ceiling tiles, etc. 3) Even if there was an adequate supply of readily combustible fuel
present, 56 minutes is not enough time to develop a fire intense
enough or large enough in extent to weaken the steel enough, given the
thermal mass of steel and concrete present (every floor had hundreds
of thousands of kg of steel and over one million kg of concrete).

Sure it is. The floors were supported on relatively lightweight trusses,
whcih have a lot of expeosed area (high surface to cross section ratio)-
this means it will heat up fast.

Not a chance. Too much thermal mass there. Way too much. You can't
selectively heat what you want without heating everything else in the
vicinity, e.g., concrete. Look up the Stefan-Boltzmann law. Hot
surfaces start radiating away huge amounts of power to the
surroundings...the power scales as T^4.

a 610UB will reach 500 deg C in around 9 minutes in a "standard" fire, at
which point it has around 20% of the original strecnght.

I think for the steel used in the WTC towers the number was about 700
degrees centigrade for 80% reduction in strength.

In any case, the WTC towers had several hundred thousand kg of steel
and over a million kg of concrete per floor. Your uninformed pedantry
and hand-waving notwithstanding, in order to raise the temperature of
this kind of thermal mass to 700 degrees centigrade, you have to
release over 3E12 J of energy (and this is neglecting losses - a
ridiculously generous constraint). To release this kind of energy in
56 minutes would require a specially designed apparatus, e.g., about a
dozen blowers the size of jet engines, to feed enough air to the
fire.

Steel starts to
weaken around 300 deg C. If you want the exact figures, it will have to
wait until Monday when I am back at work.

I already looked it up. It losses about 10% at 300 degrees C. Nowhere
near enough, and it's doubtful the fire even reached that temp over
any appreciable area in the first place.

See below

More importanly for the WTC collapse was the connections of the trusses at
each end - to the central core and the vertical columns at the preimeter.
These failed (rather than the trusses) so theends failed in sear, so the
collapesed straight down - hence the pancake.

Well, IIRC, that's not what NIST is claiming. In fact they're claiming
an inferno of 1000 degrees centigrade, and that's pure nonsense.

A house fire will easily get to well over 800 deg C. Flashover is at around
600 deg C, which is when all combustibles in the room spontaneously ignite.

You've got a steel and concrete building with approximately 2E6 kg of
thermal mass per floor, little or no "readily available" fuel, and
little airflow.

You cannot reach temperatures anywhere near the 600 to 700 degree
centigrade range in 56 minutes under these conditions. You'd have to
rig up some kind of high tech blast furnace.

the head flux to the floor is around 20kW/m2 at that time. There is a well
known ad promoting fire safety showing the effect of a ciggie lighting a
sofa, curtains to flashover in a few minutes. That is a house, which has a
comparably lower fuel load than an office (circa 400MJ/m2 vs 800 MJ /m2
typical). There is no reason why the WTC would be much cooler.

The temperature of fires in buildings has been very well researched, as it
has a significant effect on the structure (duh!) and also the premature
failure of gypsum plasterboard. The initial research was started by
Margaret Law in the UK in the 1960s at BRE (IIRC), so it is nothing new. A
major early publication was from Marguesson (sp) in Sweden with a number of
real fire tests. Depending on the fuel load and openings, temperatures
ranged up to 1200 deg C.

Sorry but you won't do it in 56 minutes, at least not over any kind of
an area.

There has been significant research into fires in commercial buildings,
given the huge market and money at stake. BHP, a major Australian steel
manufacturer did a huge number of tests in the 1980s. The Building Reserch
Establishment (BRE) in the UK built a 6 story steel office tower in an old
airship hanger at Cardington for a well known series of full scale fire
tests. A couple of friends were involved in them. These tests were fully
instrumented, so the temperatures of the members and at a number of points
around the building were recorded, and much of it has been published over
the years as it formed the basis for a lot of research and verification of
theories and methods.
An office mockup test at Cardington gave an average temperature of 900 deg
and a maximum of 1200 deg C. The unprotected steel reached 813-1150 deg C,
which is PLENTY hot enough to turn it into cooked spagetti.http://guardian.150m.com/fire/small/...m(abouthalfway down the page)
I could probably get the actual test data if I asked for it.

Sorry but you won't do it in 56 minutes.

Wanna bet? Plenty of scientific evidence says otherwise. The WTC fires were
much more severe any conventional fire for a building of the type =
multiple starts, much extra fuel, no suppression, etc.



A well known accidental fire was Broadgate in the UK. It was a conventional
office building with steel framing, concrete slabs on steel beams. The
building was under construction and hadn't had the fire rating applied.. A
fire broke out in a site shed, and was enough to severely deform the beams
and columns. The building didn't collapse due to moment redistrbution of
the load, thanks to the design of the building, with welded and pinned
joints and multiple columns. The WTC was different, with the central core
and perimeter columns, it relied on the connections at each end of the
trusses. When either the connections failed, or the trusses twisted so the
load was no longer correctly supported, it was all over.
The temperature was estimated to be around 1100 deg C for the Broadgate
fire.
More info on real fires and temperatures at:http://www.modernsteel.com/Uploads/I...7_01_fire.pdfh......
I suggest Andy Buchanan's fine bookhttp://www.amazon.com/Structural-Design-Safety-Andrew-Buchanan/dp/047...

A key difference between the WTC and natural fires was the development of
the fire. In a normal fire, it will start at a single point of ignition -
say an overheated computer, and spread through the floor as neighboring
items ignite until

...

read more »

It is impossible to debate with an insane fanatic who thinks the green
men did it.

On Nov 6, 1:51 pm, sparky wrote:

It is impossible to debate with an insane fanatic who thinks the green
men did it.

I am still waiting to find out which institution he graduated from.


Dan

On Tue, 06 Nov 2007 02:49:54 -0800, wrote:

On Nov 6, 3:51 am, Geoff wrote:
On Mon, 05 Nov 2007 05:45:06 -0800, wrote:
On Nov 5, 5:02 am, Geoff wrote:
On Sun, 04 Nov 2007 03:31:03 -0800, wrote:


snip

An office mockup test at Cardington gave an average temperature of 900 deg
and a maximum of 1200 deg C. The unprotected steel reached 813-1150 deg C,
which is PLENTY hot enough to turn it into cooked spagetti.http://guardian.150m.com/fire/small/...m(abouthalfway down the page)
I could probably get the actual test data if I asked for it.

Sorry but you won't do it in 56 minutes.

Wanna bet?

Yep.

Look at the Cardington tests - a standard office hit 600 degrees in 40
minutes. That was without a plane fuelling the fire.

Even if "SOME" burnt outside the building? Well the videos are
available on youtube. The videos speak for themselves. Apparently
you've got it backwards: if SOME actually burnt inside the building
(in the case of WTC2 at least) it wasn't much.

IIRC, NIST did their simulations assuming something like 40% burnt in
the building, and as I recall, they never explained how they arrived
at that figure...and to the extent they're wrong about important
initial conditions, their whole simulation is wrong.

So have you asked them to justify that assumption? I am pretty sure that it
is well justified, given the nature of academic bloodsports and the amount
of research done throughout the world on the WTC.

Fire engineering relies on a known (or probable) fuel load for
calculations. Adding a significant amount of extra fuel (plane, contents,
jet A1) makes those calculations rather moot. It is for that reason, if you
want to turn your extra high office atrium into high rack tyre storage,
your local building code officials will want a say in the matter.


Bull****. It's plain to see *from simple calculations* that MOST if
not ALL of the jet fuel went up in a cloud outside WTC2.
The size of the fireball basically accounts for ALL the fuel...if any
was left inside it was probably an insignificant amount.

Simple calculations?
You also forget the plane itself, a somewhat higher fuel density than the
building itself.

But the fact is it wouldn't have mattered if you filled the whole
****ing building up with the hydrocarbon fuel of your choice, you
simply cannot burn enough fuel in 56 minutes time (without a specially
constructed apparatus) to heat 2E6 kg of construction materials up to
600 - 700 degrees centigrade.

You don't have to heat the whole building up, only the important bits.

Not if you're using judiciously placed thermite and/or explosives, you
don't. If you're going to depend on randomly scattered fires then you
would generally have to, no? Unless you're going to claim that somehow
by magic, the fire/heat only went where it needed to go to cause
collapse? Last time I cooked a pie in the oven, I had to waste energy
heating the inside walls of the oven and even the room itself, to a
certain extent. If you've found a way to only heat what you want, what
are you doing working? Why aren't you out cruising the Caribbean on
your yacht, for example?

So, your oven heats the walls all the way through, instantly? It doesn't
reradiate any energy into your dinner?


That
is why fire protection is added to steel beams. it isn't to make some
applicator companies rich you know. If it wasn't necessary, it wouldn't be
done.

In what sense is it deemed "necessary" and how do *you* personally
know it's "necessary"?

Have I been in a burning building that was collapsing? No, I was outside.
It was bloody hot and over 800 degrees is not unlikely judging from the
colours. Being a part time blacksmith (this being a metalwork group and
all), judging temperature by colour is part of the job.

As the fire protection biz is a 35 billion euro (about $US1.95 this week)
business, I think you are stretching the conspiracy theory a little far if
you think that the worldwide fire engineering fraternity and building code
officials everywhere in the world are part of a big plot to add a
significant cost and aggravation to building.
Especially since people have paid me money to remove the fire protection,
by showing that the beams and columns will not reach failure for the load,
given the expected fire size and duration. None of these calculations
included a plane as part of the fuel load.

snip
Well how effective will insulation be after a fire burns for many
hours? The "One Meridian Plaza" fire burnt for 18 hours and involved
many floors, seven of those hours without any firefighting efforts at
all. According to "Simpson Gumpertz and Heger", "the twelve-alarm fire
burned for 18 hours. The extreme heat caused window glass and frames
to melt and concrete floor slabs and steel beams to buckle and sag
dramatically."

Let's see, if the steel beams "buckled and sagged dramatically", then
either the beams weren't insulated or the insulation wasn't much good,
no? Yet the building still didn't collapse.


I thought you said that was impossible? That it couldn't get that hot for
steel to lose it's strength? Sounds like it was over 500 degrees to me.
Your comment demonstrates what I said about load transference. Take half
those structural members out (central core and perimeter frame in the WTC)
and see if it works. It also depends on the structure itself. The WTC was
unusual due to the height, which forced the use of a lightweight truss,
rather than the conventional (and overbuilt) concrete columns and beams
with tensile slabs. Concrete is good stuff in fire - it lasts very well.
The usual failure mode is the reinforcing overheats and fails, or spalling,
exposing the reinforcing. Steel turns to spaghetti At this point it falls
over..

It also didn't have an airplane providing several tons of combustibles and
fuel. the plane itself provides many tons of plastic, oil, rubber,
bodies,luggage, packaging knives and at least some jet fuel. Fire
protection systems are designed.

There are a number of examples of collapsed buildings around the world.
Have a look at "Structural design for fire safety' by Andy Buchnanan, page
171 for some nice pics of a collapsed movie theatre, industrial buildings
and others from a fire. Pge 25 for the Ballantynes fire in Christchurch
(1948, killed 43 people, gutted a city block), page 25 for a shopping mall
where the roof is collapsing. Some nice steel spaghetti there. Since i have
seen some of these myself, I don't think it was a photoshop job.


Well, yes, assuming you have enough oxygen available. You can't get MW
of heat for any length of time without lots of airflow. You may have
adequate air near a broken widow or hole in the wall, but what about
everywhere else? You can't do it in 56 minutes.

There was an airplane sized hole in the side of the building - unless you
are saying that a plane didn't actually fly into the building. Getting air
throughout the floor is less of an issue than you think. Research on
burning behavior in deep rooms dates bake to Kawagohe in Japan in the
1950s. Airflow is very turbulent and promotes burning throughout the room.

Geoff

It is impossible to debate with an insane fanatic who thinks the green
men did it.

Yup, ignorance is a curable condition, stupidity is terminal. I think this
one is beyond hope.It is like arguing religion with a True Believer. It
doesn't matter that the Beloved Leader was a flake who i sin it for the
money, they just KNOW they are right.
At least most RCM readers are thinkers and engineering types who understand
how things work (apart from a few trolls).
Take care, keep your smoke alarm batteries fresh, and have an escape plan.
Geoff