Math Problem: World Trade Center

[Alpine Trooper]

The National Institute for Standards and Technology determined the two World Trade Center towers collapsed from the stress of concrete pulling inward on the damaged building.

Both planes hit below the 100th floor. The World Trade Centers have 110 floors. From the 9th to 107th floor, there are 59 perimeter columns that are 14in in width and 13.5in in depth. The majority of this steel is above 60ksi, getting stronger as you go higher. The middle of the WTC is supported by 47 heavier steel columns, 10 of which are massive box columns that are rated around 40ksi and are 12in x 52in. The melting temperature of iron is 2800f. Jet fuel burns at 550f.

If the official cause of the buildings collapsing was concrete pulling in on these massive beams, which is a first, why did we discover pools of molten steel in the basements?

http://wtc.nist.gov/

 

[Bigfoot3814]

Is there a banana in your pajama?

Moderator Action: Warned for spam.
Please read the forum rules: http://forums.civfanatics.com/showthread.php?t=422889

 

[Perfection]

Extensive analysis on the subject shows that it must not have come from the planes

 

[Alpine Trooper]

Hey, don't call me a conspiracy theorist if you can't explain all the melted metal but concrete being the reason why it collapsed. =p =p =p I am simply asking a question!

And yes there is a banana in my pajama, its bouncing here and there

 

[draggar]

The metal beams didn't melt - they expanded (thermodynamics) causing the support bolts to lose their ability to hold it together. As the beams sagged (due to the heat) it created more pressure on the bolts - which failed. The vision people have of the "melted beams" is the twisted metal in the debris field. The metal twisted from all of the pressure during the collapse.

Add in the damage already done by a very large object hitting the building at a very high rate of speed is what caused the structures to fail.

The fire didn't make them collapse and neither did the collisions -> it was both of them combined.

Like many catastrophic failures, normally one or two failures won't cause the whole system to fail but when several happen at ones, it fails (we had this issue with our nuclear power plant a few months ago).

 

[Cutlass]

Ever see a film of a blacksmith at work? Same principle applied in the WTC collapse. You do not melt the metal, you heat it until it is malleable. And then you place enough pressure on it to change its shape. A blacksmith does that with a hammer and anvil. At the WTC it was done with the weight of the building above the burning floors.

 

[Earthling]

The melting temperature of iron is 2800f, at STP

Probably fixed (don't know what your exact source is on this). At any rate, there would not necessarily have to be a temperature as high as you suggest to deform/destroy the building. Massive amounts of force from the collapsing structure would suffice; I'm sure shear forces and the like were at work even if only the "top" was hit by the planes. If anything the fact that molten steel (I don't have the exact figures on this either) is in the basement confirms massive pressure on the foundations (as opposed, to say, molten steel randomly on the 50th floor while people were escaping).

Likewise, all the other figures you are stating are theoretical values for the strengths of the steel beams - nobody actually built WTCs before and demolished them to test the design. Just because the buildings might theoretically have been sturdier doesn't mean they were. Look at how many bridge designs or other structures in history were thought to be very strong but had many weaknesses. If simply taking lower than the hypothetical best figures would solve your problem, and I suspect it would, go with that.

 

[Alpine Trooper]

Stop Stop Stop lol

I Said The Reason The Wtc Fell Was Because Of Concrete Now Explain Why There Is Melted Steel In The Basement

obviously i am saying i dont think the steel melted but the melted steel didnt come from nowhere

 

[Earthling]

Draggar explained it much better than me, but once again: massive amounts of pressure (and thus you don't have to have a high temperature) on the beams/foundations that were trying to support the structure.

 

[Alpine Trooper]

So massive amounts of pressure cause 60ksi steel to turn to molten and harden in the basement?

 

[Ziggy Stardust]

I'm getting a file not found from your link AT.

By the way, the jet fuel would have been burned up after about 10 minutes. So the burning temperature of jetfuel is not really relevant here. After 10 minutes the fire fed of other sources.

 

[Alpine Trooper]

I'm getting a file not found from your link AT.

http://wtc.nist.gov/

 

[BSmith1068]

The wreckage also burned for quite some time after the buildings fell. It is possible that the temps were high enough in these fires to melt the steel, but it happened after the fall.

 

[draggar]

So massive amounts of pressure cause 60ksi steel to turn to molten lava and harden in the basement?

If enough steel is soften enough to be malleable then a lot of it together can easily look like molten steel - the pressure from the buildings can press it together to make it look like it was molten and then hardened.

Take a bunch of marshmallows in your hand and squeeze them all - they can bunch up together and look like they melted and then rehardened. Did they? No. (And no, it's not the same but very similar).

The wreckage also burned for quite some time after the buildings fell. It is possible that the temps were high enough in these fires to melt the steel, but it happened after the fall.

Considering it was underground and extremely well insulated, it is extremely possible that the area in question turned into a gigantic kiln / oven. The heat was kept in the area as the steel was malleable and the pressure from the rest of the building formed it into a glob.

 

[Alpine Trooper]

The wreckage also burned for quite some time after the buildings fell. It is possible that the temps were high enough in these fires to melt the steel, but it happened after the fall.

what would fuel something that burns above 2900f?

 

[Alpine Trooper]

If enough steel is soften enough to be malleable then a lot of it together can easily look like molten steel - the pressure from the buildings can press it together to make it look like it was molten and then hardened.

Take a bunch of marshmallows in your hand and squeeze them all - they can bunch up together and look like they melted and then rehardened. Did they? No. (And no, it's not the same but very similar).

The jet fuel burned immediately, flames couldnt have been hot enough to make even 40ksi steel malleable. Not to mention how much steel there was.

 

[Ziggy Stardust]

http://wtc.nist.gov/

Thanks. Now where do I find the report on pools of melted steel in the basement?

 

[draggar]

The jet fuel burned immediately, flames couldnt have been hot enough to make even 40ksi steel malleable.

The fire burned for weeks. Everything in the building that was flammable burned after the collapse.

You're looking at two different results - the buildings failing and the "molten" steel in the basement.

Concrete is extremely heavy and a great insulator so the weight of that could have contributed to the collapse and the pressure / insulation to form the steel at the bottom.

I'm done with this thread, too.

 

[ThePrussian]

what would fuel something that burns above 2900f?

Thermite. Which could occure quiet naturally in a building.

 

[Alpine Trooper]

Thanks. Now where do I find the report on pools of melted steel in the basement?

I am talking about the salvage effort after the trade center collapse. There were large pieces of steel melted together. I don't have a source, I figured this was common knowledge. I am just looking for an answer as to why there was steel melted together if there was no heat hot enough. But apparently days of fire and pressure could do that. Thanks!