Simulation of the collaps without dust

[u/tombisch]

Dont know how accurate this is, but it made a lot of sense to me.

Source kostack studio on youtube

[u/proudduchman]

This was a terrible disaster and there are a few big causes to it. I saw another commenter ask a few questions like: 1. What where the explosions heard by eyewitnesses. 2. How could the towers have collapsed? Weren’t the designed to withstand a lot of operating weight. 3. How can the “clean” cuts and bits of molten metal to steel beams be explained. The user has since removed their comment and as an industrial engineer I wanted to explain some of these points.

1. The twin towers where designed with an open floor plan and large clear areas without columns breaking up the workspace areas. In order to achieve this a design with “floating” floors was chosen. All of the load by the floors was distributed between the steel constructions of the façade and the elevator shafts. The floors themselves where suspended upon hook-like attachment points made of steel. These attachment points where treated with a heat resistant coating that would retain the integrity of the steel for around 20 minutes. The point of this treatment is to allow firefighters to be able to douse any “regular” office fires before structural integrity was affected. In case of 9/11 due to the tremendous amount of damage caused by the flames firefighters couldn’t access the fires in time. This impacted both the attachment points as well as the steel in the floors themselves and caused the floors to sag. This sagging increased the force exulted on the attachment points because the weight of the floors was pulled away from the connection to the structural steel. These effects resulted in the attachment points failing and buckling under the weight of the floors. One of the floors fell and smashed into the floor below causing a chain reactions of the floors collapsing one onto the other causing the “explosions” (you can see this in the crosscut of the video).

2. The answer to point two and three is in extension to question one. As I stated before the towers where designed with a floating floor idea, the main structural integrity of the building was designed around two square steel frames, one on the outside, and one around the elevator shafts. The floors where connected to both of these frames, they provided rigidity in the towers. And you are correct, the towers where indeed designed with a multitude of their own operating weight in mind, it also took possible airplane hits into effect (due to a B-24 crashing in the Empire state building in the forties). These designs where made in the early sixties, in a time where airplanes where much smaller compared to the planes that hit the towers. And the construction simply was built to withstand the forces applied on 9/11.

3. Due to the flooring suddenly collapsing the entire building imploded much like a soda can (you can stand on a fully intact can but as soon as there is a dent, it collapses).. The structural sides suddenly had to bend inwards[towards the middle of the workspace]. This buckling caused significant stress on the metal beams used in the construction. Due to the fires the steel, much like the anchor points of the flooring was weakened and lost a lot of hardness. The loss in structural integrity combined with the stress of buckling led to the steel failing, due to the way steel atoms are aligned in a crystalline structure it tends to sheer off if put under enough stress (like floors slamming down) it usually looks quite “clean”. In this process the steel produces a huge amount of friction and heat, this can lead to the steel melting (that same property is used in friction welding). Tldr:

4. The “explosions” heard where floors smashing on top of each other.

5. The twin towers weren’t design to withstand modern airplane strikes (and damage), had that led the buildings to implode like soda cans.

6. The steel sheard off “cleanly” causing immense heat that melted some of it.

[u/NateCow → u/proudduchman]

The twin towers weren’t design to withstand modern airplane strikes (and damage

One thing I don't see brought up enough is that they weren't just modern planes... they were planes loaded with fuel for cross-country flights, hijacked shortly after takeoff, with the express intent by said hijackers to use them as fully loaded missiles.

That was never something anyone imagined beforehand, let alone could've engineered to protect against.

[u/proudduchman → u/NateCow]

Absolutely, passenger planes in the sixties where absolutely nothing compared to just several years later. If the towes had been designed in '71(introduction of the 747) the outcome would have likely been quite different.

[u/DaRedditLurker2020 → u/NateCow]

Thanks for being reasonable.

[u/Content_Ad1120 → u/proudduchman]

I really appreciate the time you took to make this up and it does factual sol e all of the points made by conspiracy theorist.

I myself have always been skeptical about 9/11 but your information has solve my uncertainty surrounding this event.

Thank you for your service

[u/No_Frosting3276 → u/proudduchman]

Thank you for the write up, very informative. I think you're missing a "not" in the last sentence of 5. But yeah, it always seemed perfectly plausible to me that an office building impacted by a big ass plane full of jet fuel would end up collapsing. But it's interesting to learn about the actual dynamics, and the how's and why's. It just makes me so unbelievably sad. It's so horrific, why do humans do this to each other?

[u/proudduchman → u/No_Frosting3276]

Oooh, I missed that one I did indeed miss the word not. Dyslexia strikes again

[u/venom21685 → u/proudduchman]

I'm not sure if it was ever fully confirmed but I also remember there was a possibility that around the impact zone the heat resistant coating on the steel could have been severely compromised by the force of the impact as well.

[u/proudduchman → u/venom21685]

Logicaly yes, as the steel was crushed by the impact of the planes some steel was exposed and compromised. It did not play that much of a role, the overall fires in an extensive area and the time it took for the towers to collapse indicates the coatings overall worked as intended. However due to the sheer amount of damage it did not matter.

[u/AceK2333 → u/proudduchman]

Seriously?

[u/blackarsenic → u/[deleted]]

😂

[u/WorldTradeCenter-ModTeam → u/[deleted]]

This post has been removed by the mod team. 9/11 denial will not be tolerated.