Lets Talk About Fire

[NYCEMT86]

As I am reading through the threads catching up on the past few months of not lurking through the sub-forum, I see the argument that fire wasn't enough to destroy 3 buildings in one day rearing its ugly head still. First of all, I am not arguing that fire alone caused the collapse of the 3 towers. The biggest piece of the puzzle would be the damage created by the two aircraft that flew into the towers to begin with. What I am saying though is that fire most certainty had a contributing factor to the collapse all 3 buildings.


So now, I would love to know why fire and the damage from the aircraft couldn't have brought down the WTC. I am more than happy to address any questions that the truthers may have.

 

[alienentity]

Dude, you've missed the part where no planes actually hit the towers....

 

[Architect]

About a year ago I started a thread specifically raising the perceived fire-resistant nature of steel structures and Truthers concerns regarding involvement of such a failure mode on 9/11.

None of them responded.

 

[HannibalGroup]

About a year ago I started a thread specifically raising the perceived fire-resistant nature of steel structures and Truthers concerns regarding involvement of such a failure mode on 9/11.

None of them responded.

Could you send me a link to that thread, or share your initial questions?

 

[NoahFence]

Truthers can't put the two together.

It's either Aircraft damage can't do it.
or
Fire can't do it.

They never touch upon BOTH at the same time.

 

[ergo]

Truthers can't put the two together.

It's either Aircraft damage can't do it.
or
Fire can't do it.

They never touch upon BOTH at the same time.

Actually we point it out to you all the time:

There was no airplane damage in WTC 7, and structural damage was minimal, unless NIST is willing to admit to and release evidence of a 20-storey gash in its south face. Apparently they didn't consider that significant enough.

Structural damage AND fire in every other WTC building, and in many surrounding buildings. No progressive collapse! Wow!

 

[NoahFence]

Actually we point it out to you all the time:

There was no airplane damage in WTC 7, and structural damage was minimal, unless NIST is willing to admit to and release evidence of a 20-storey gash in its south face. Apparently they didn't consider that significant enough.

Structural damage AND fire in every other WTC building, and in many surrounding buildings. No progressive collapse! Wow!

Incorrect.

release evidence of a 20-storey gash in its south face.

Perhaps if you spent less time lying on a message board, and more time actually researching, you'd have seen it by now. I have.

 

[CptColumbo]

Read the studies and look at the pictures from the fire in the Mont Blanc Tunnel.

Margarine destroyed a semi-truck. Burned it down to the axels.

 

[leftysergeant]

Structural damage AND fire in every other WTC building, and in many surrounding buildings. No progressive collapse! Wow!

Thosebuildings were of normal construction with nearly no free-span trusses supporting the floors.

Basicly, in both the towers and WTC 7, the floors more nearly ressembled roof trusses more than they did normal floors.

Roof trusses fail in fires of any magntude over a long enough exposure to heat.

BOOM.

 

[sts60]

Oh, come on, are you saying you wouldn't be happy advancing a line into one of those big box stores where the bar joists overhead had been exposed to fire for half an hour? There's no chance they'd collapse on you; they're steel!

 

[DGM]

Oh, come on, are you saying you wouldn't be happy advancing a line into one of those big box stores where the bar joists overhead had been exposed to fire for half an hour? There's no chance they'd collapse on you; they're steel!

I'm in those "big box" stores all the time. It looks like the roof trusses are only painted. Is this true?

 

[Grizzly Bear]

Thosebuildings were of normal construction with nearly no free-span trusses supporting the floors.

The sad thing is... that's one of the most basic things that never pops up in their minds.

 

[1337m4n]

There was no airplane damage in WTC 7

 

[triforcharity]

I'm in those "big box" stores all the time. It looks like the roof trusses are only painted. Is this true?

It depends on the fire loading of the store, typically. (at least in Florida anyway)

From my experience, grocery stores typically have much lower fire load, and as such, their trusses seem to be less frequently protected by SFRM than in some places.

Now, a few months back, I went to a local furniture store, and happened to notice the SFRM on the trusses. So, I got to thinking and doing some math in my head.

A grocery store would have about 500-700MJ/m²in my estimate. Then, there is the furniture store where it is maybe 4-5x's that, at around 4500-4800 MJ/m². Clothing stores, book stores, and the like have even higher fire fload, at around 5200MJ/m².

So, in my opinion, it depends on the fire load, and the type of sprinkler system installed. But, I am not a fire protection engineer.

 

[Skeletor]

I know I'm new here and all, but there's a simple equation that I've thought out about this whole mess:
Airplanes + High Speed + Lots of Jet Fuel + Twin Towers = Fire + Collapse

Riddle me this, Truthers: If WTC 7 was wired with explosives to begin with, why go through all of this other rigamarole, and simply flip a switch and blow it up with all the people inside? The same goes for WTC 1 & 2...why bother with the show of airplanes and fire and smoke, when you can "pull" all the buildings down without any witnesses? (i.e. news cameras pointing at the towers)

 

[Animal]

It depends on the fire loading of the store, typically. (at least in Florida anyway)

From my experience, grocery stores typically have much lower fire load, and as such, their trusses seem to be less frequently protected by SFRM than in some places.

Now, a few months back, I went to a local furniture store, and happened to notice the SFRM on the trusses. So, I got to thinking and doing some math in my head.

A grocery store would have about 500-700MJ/m²in my estimate. Then, there is the furniture store where it is maybe 4-5x's that, at around 4500-4800 MJ/m². Clothing stores, book stores, and the like have even higher fire fload, at around 5200MJ/m².

So, in my opinion, it depends on the fire load, and the type of sprinkler system installed. But, I am not a fire protection engineer.

It is a combination of construction type, use group, area, height above grade, fire suppression system and building access.

IN a nut shell........construction type and use group limit the allowable area and height of a building, fire suppression and building access (public way around perimeter of the building) increase the allowable area of the building.
If you need a greater building area, then you typically change the construction type (which typically means protecting building structure) which increases your allowable area. There is also one major exception to those limits....an "unlimited area building" which is limited to 1 story, use group B F M and S, building type other than 'V', sprinkled and has a 60 ft public way around the entire building.

Just another little tidbit, exposed steel may also be painted with intumescent paint. It will appear to be just painted steel, but it actually is a rated assembly equal to the SFRM

 

[triforcharity]

^^ This. is why I am a professor, and not an engineer!

Yes, you're correct though. But, that sounds like building codes and engineering, and such that I have limited knowledge about. VERY informative though!

ETA: That **** is incredible! 3.5 hours average protection time!! That stuff is awesome! (New technology is ****** killer!!)

http://www.albi.com/cladtf.html

 

[alienentity]

I know I'm new here and all, but there's a simple equation that I've thought out about this whole mess:
Airplanes + High Speed + Lots of Jet Fuel + Twin Towers = Fire + Collapse

Riddle me this, Truthers: If WTC 7 was wired with explosives to begin with, why go through all of this other rigamarole, and simply flip a switch and blow it up with all the people inside? The same goes for WTC 1 & 2...why bother with the show of airplanes and fire and smoke, when you can "pull" all the buildings down without any witnesses? (i.e. news cameras pointing at the towers)

You're being logical, that spoils the illusion. You've got to buy into the myth the way you do when you go see a Harry Potter movie - anything you can imagine is now real....

 

[Dash80]

You're being logical, that spoils the illusion. You've got to buy into the myth the way you do when you go see a Harry Potter movie - anything you can imagine is now real....

My 15 year old cousin is obsessed with Twilight, I swear she thinks Edward Cullen (pastey faced pansy vamp) is real. Truthers are a little like hardcore Twilight fans. Those books (ashamed to admit that yes I've read them) are devoid of logic, have plot holes the size of a small country and the author claims her vampires are scientific, but messes up the basic principles of physics, biology and chemistry.

 

[NYCEMT86]

Actually we point it out to you all the time:

There was no airplane damage in WTC 7, and structural damage was minimal

Source?

...<Snip>....
Structural damage AND fire in every other WTC building, and in many surrounding buildings. No progressive collapse! Wow!

That is because the construction of the WTC 5 and 6 was gerber framing. Similar to the Empire State Building. In fact, structural engineers went into see the damage of WTC 5 to see that 4 stories, not involved in the immediate damage from falling debris from the WTC 1 & 2, collapsed to due heavy fire load.

http://www.structuremag.org/article.aspx?articleID=525