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[–] GoodGodKirk 0 points 1 points (+1|-0) ago 

Wut? Are you an engineer? The metal used for the buildings can withstand the fires of jet fuel, especially when encased in cement.

It could weaken the metal, which may bend, but that doesn’t explain the tower falling on itself rather than falling to the side where the support was weakened.


[–] KnightsofHubris 0 points 0 points (+0|-0) ago 

Wut? Are you an engineer? Not an engineer but I looked into this pretty deeply, reading comments from some real deal scientists.

Jet fuel did not bring the building down, an ordinary office fire did. The jet fuel probably burned out within 10 minutes. What the jet fuel did do is immediately cause an enormous fire, this is not how normal building fires start.

It's very very well known that steel weakens in fire when unprotected. In Civil War when the Union Army wanted to deny the Confederates the use of the railroads, they would make "Sherman Neck Ties" by heating railroad rails in a campfire and then bending the soft metal around a tree.

This image is from a fire test done on an office. The upright columns were protected and the horizontal beams were not and as we can see the beams bowed in the heat.

The metal used for the buildings can withstand the fires of jet fuel, especially when encased in cement.

This is not how the WTC towers were built. The core of the WTC was steel not concrete. They used spray-on foam fire retardant rated for 2 hours I believe. The Rockefellers wanted giant open office spaces without massive concrete encased columns everywhere. This is was the usual way skyscrapers were built and one reason why the Empire State Building survived the plane crashing into (another was it was a much small plane going much slower) The ESB had tons of concrete and was a much heavier building per square foot. The architect's solution to this was move the interior columns to the center of the building to create a very strong core supporting about 60% of the building's weight. And then put a lattice of thin columns all along the outside of the building. This perimeter columns supported about 40% of the weight. The core columns were so strong, you can still see then standing for like 10 seconds after the clouds of dust pass.

but that doesn’t explain the tower falling on itself rather than falling to the side where the support was weakened.

The tower would not fall over on it side. There's no force strong enough to make it tip over. The tops of one of the towers was leaning before collapse but fell straight down because by that point gravity was the strongest force working on it. The Tower was a system of millions of parts and it got its strength from all this parts working together and this system is intended to be strong in a vertical direction. It would not tip over, because it would break apart long before then just due to gravity.

The full collapse of the towers was long and slow. There was plenty of structural damage before the final collapse. When the planes smashed in, they severed many perimeter columns and some core columns. The building still stood because of redundancy built in, the weight was transferred to the remaining columns. This meant the intact columns were now bearing more than their usual weight. The floors at the point of collapse had given out and were sagging inward. The strong connections of the floors to perimeter columns actually pulling these columns inwards from both sides of the building. So the columns at the point of collapse were A. Overloaded. B. Bent in slightly. C. Extremely Hot. Once the final collapse started it was a chain reaction of failure that point, they all went in a split second.


[–] KnightsofHubris 1 points -1 points (+0|-1) ago 

I'll address some other comments here


That's actually incorrect! It wasn't hot enough to melt that steel:

Steel loses strength as it is heated. There's no need for it to melt for a building to collapse. Blacksmiths can shape steel by heating it and applying force. Here's a bunch of men bending a heated train rail around a tree.


I think the twin towers are the only buildings in history that have ever fallen due to fire.

This is not true. It's well known that steel structures (as opposed to other kind of construction) can find quite easily due to fire. In 1960 Chicago's convention center had a massive fire and the entire roof collapsed before the fire was out. The building was thought to be fireproof. For this reason, engineering codes require you to protect steel in some way. Some buildings use entirely concrete core columns. Some use steel columns surrounded by concrete. Some use steel columns with spray on fire-retardant. The WTC used the later and there were sevral indication the WTC had problems with its fireproofing even before the planes smashed through.

The WTC buildings were the first skyscrapers to collapse due to fire but they are not unique

This building in Brazil collapsed in May.

This one in Iran was in 2017

So bopper, did you know that in 1945 a military plane crashed into the Empire State Building? The building caught on fire, but it didn't collapse into its own footprint shockingly!

And the Empire State building was built entirely differently than the WTC and the impact of the planes was substantially smaller as clamhurt points out.

Also the idea that the WTC collapsed in its own footprint is a silly talking point. The North Tower fell on WTC 7 and set it on fire. Do you know how far away WTC7 was from the North Tower? If you ever go the WTC memorial check it out for your. Several other building were destroyed as well because the towers did not fall into their own footprint.