r/NoStupidQuestions • u/JMRooDukes808 • 6d ago

Do you think the 9/11 hijackers knew that the WTC buildings would collapse?

I really don’t know where else to ask this. There is obviously an overload of information about the event itself online, but one thing I can’t find out is if the hijackers intended to, or knew that the WTC buildings would collapse. Do you think they just planned on the impact and fires to be the extent of the damage caused? As far as I know, no steel structure buildings in history had collapsed from fire at that point, so it makes me wonder if they actually “succeeded” in their plan more than they intended.

Edit: no conspiracies please, that was not the point of my post

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u/MoreGaghPlease 6d ago

So we actually have a told answer to this both from tapes of Bin Laden found in Afghanistan early in the war and from evidence given by KSM when he was being tortured by the CIA.

Bin Laden did not expect the towers to collapse, and they were secondary targets. The main targets were the White House and the Pentagon, and he believed that both would be destroyed if the planes hit their target (obviously the Pentagon was only damaged, probably they did not appreciate how big it is). But they did not expect the towers to collapse. They had no knowledge or understanding of the engineering of the towers, they believed that it was likely to cause a fire and maybe kill the people above the impact. But they also didn’t care very much or really think about this aspect of it, it was more like something that they just mused about.

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u/sboaman68 6d ago

My grandpa was an engineer on the twin towers when they were built. My mom was talking to him on the phone after they were hit. He assured her that there was no way those towers were going to come down while they both watched the news. When the first tower collapsed, my mom said he started to get some emotion in his voice(very rare for him to show emotion of any kind) and quickly ended the call. As far as I know, he never talked about what happened to anyone I knew after that.

I also highly doubt the terrorists knew they would come down. They just struck them for the symbolism.

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u/moonbunnychan 6d ago

There's a History Channel doc about the WTC where they were interviewing one of the designers and he talks about how they built it to be able to survive a plane crash. But it was designed to sustain the damage of a much smaller plane, not a giant jet.

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u/iamiamwhoami 6d ago edited 5d ago

It wasn't the impact that brought the towers down. The burning jet fuel dripped down the inside of the structure and melted the support beams.

Edit:Weakened not melted

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u/KeyDx7 6d ago

Don’t even have to melt them. This is where that “jet fuel doesn’t…” conspiracy comes in. Steel only needs to be softened, which can be done in a wood fire, to the point where it loses like 90% of its yield strength. Softened steel beams would have trouble holding themselves up, let alone the top portion of a building, and this happens well below steel’s actual melting point.

Any liquified or “flowing” metal supposedly seen by bystanders was probably aluminum, which melts at a much lower and easily attainable temperature.

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u/Comfortable_Many4508 5d ago

growing up i assumed metal getting weaker was common knowledge and the jet fule was just a dumb joke. but i guess a lot of people have never heard of blacksmithing

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u/woyboy42 5d ago

Beyond the “jet fuel burns at x degrees” nonsense…

  1. You put heat into a confined space, the temperature will increase and keep on increasing. You can’t just say the temperature inside only reached the flame temperature. Think kiln….

  2. As low as 300degC can decrease the strength of concrete by 50%, higher temps up to 80%. First it expands, then contracts, then explodes. With temperature gradients across the affected floors the concrete beams and columns would have torn themselves apart.

With all the weight above them, enough heat for long enough it’s not surprising something eventually gave. The floor below then had all that weight plus the momentum and shock load, so not surprising it also failed as it would also be heat damaged and weakened.

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u/NickRossBrown 6d ago

Everyone knows that steel beams only bend when they’re completely melted. Jet fuel doesn’t melt steel beams. Steel beams only bend when their melted.

https://youtu.be/FzF1KySHmUA?si=Qy1mD2ahBFnp4rsQ

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u/careythepriceisright 6d ago

This video is awesome, thanks for that.

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u/RainbowBier 5d ago

aww i know that video i love it

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u/Efficient_Bag_5976 6d ago edited 5d ago

No beams were melted. They lost strength and started bending. 

 Once support beams start buckling, a building is doomed

If you ever go open plan on your house and put steel beams in, you are required to coat them in intumescent (fire retardant) paint, otherwise a small fire could cause your house to collapse

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u/TopShelfWrister 3d ago

Is the requirement for intumescent a relatively new requirement? Why would the steel beams in the twin towers not have been coated in a fire retardant product? Or were they and the retardant quality of the coating just lost efficacy after exposure to the fire for a while?

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u/Efficient_Bag_5976 2d ago

They were coated, sprayed with SFRMs and plated with gypsum boards. But the crash knocked a huge amount of it off in the crash zone.

If it was JUST a fire, or just an impact, or, a smaller airliner, the towers wouldn’t have fallen.

But the combination of the speed, size, damage to the core columns, fire protection, and THEN fire doomed the buildings.

There were investigations that found the fire suppressant to be insufficient, and WIKI says it was being upgraded, but had only been done in the first 18 floors (in expectation of another 1993 bombing)

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u/seweso 5d ago

Why perpetuate the idea that beams were molten? Can you edit?

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u/StartingToLoveIMSA 5d ago

Not melted….just superheated from the burning fuel to where they lost all ability to bear the loads they were designed to withstand.

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u/theshrike 6d ago

So jet fuel can melt steel beams? :D

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u/RainbowBier 5d ago

no jet fuel can bend beams after burning and heating them for 30+ minutes

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u/theshrike 5d ago

I keep forgetting that a good portion of redditors weren’t born when it happened.

It’s a fucking meme older than you: https://knowyourmeme.com/memes/jet-fuel-cant-melt-steel-beams

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u/RainbowBier 5d ago

im aware of the "meme" and i was alive when it happend, summerbreak 2001 came home one evening with my family infront of the tv in germany talking about a war coming

my brother served from the isaf base in termez as helicopter gunner for casevac and supply runs

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u/RainbowBier 6d ago

a realistic impact would be a lost plane in fog and at the time the biggest jet liner was a 707

nobody expected a full speed collision with a modern jetliner

also it was most certainly the massive fuel spread over multiple floors and the fire having a field day, looking at the footage you can see how it just eats through the towers with extreme speed

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u/HustlinInTheHall 5d ago

Yeah there had already been plane crashes into high rises, but usually smaller craft. It would make sense to plan for a jumbo jet but you'd still be assuming someone lost, not deliberately going full speed.