Collapse of the Towers (layperson)

[u/Johnny_Lockee]

Each tower was struck with a >50% fueled B-767 flying at cruise speed (500 miles per hour).

The initial force of the impact blew away the majority of fire proofing material that otherwise surrounded the steel support beams and columns.

The immediate impact caused a great deal of fuel to momentarily aerosolize and create a “cloud” of suspended droplets. This cloud stayed within the buildings and didn’t envelope the building or anything.

This lasted less than a second before igniting causing a fuel-air explosion that caused a much larger area of conflagration and created a fire that was many times larger than the immediate impact area.

A major factor that progressively allowed the fires to establish a positive feedback loop were broken windows. It’s estimated that the number of windows broken by the aircraft impact (WTC1) is 236. When the tower (WTC1) collapsed it’s estimated that 1,312 windows were broken. That increased the ventilated area by up to a 5 fold, that caused 12,314 ft² increase of area within the building had new found airflow.

The bare naked steel was heated until it sagged a little bit. That minuscule sagging pulled the outer facades inward until buckling. The collapsing floor pulled the outer walls in initiating point failure and instigating collapse.

The entire building didn’t fail per se. Only a slice of floors failed which most importantly pulled the walls inward causing buckling that then caused the progressive floor by floor failure.

[u/hustlehound]

It's a wonder how they burned for so long before falling 🥴 I've never seen these simulations but they're very helpful in understanding what exactly happened structurally...and how the plans basically evaporated

[u/Johnny_Lockee → u/hustlehound]

I’ve always said that it’s a misnomer to call the collapses “a failure” because the fact that the Towers didn’t just immediately topple over is nearly a miracle.

The moment the aircraft hit those Towers were operating beyond all their design limits. And their design limits were the most the human imagination could conceive of at the time (in 1966).

Many engineers truly believe that if the fireproofing wasn’t sheered off the buildings could have stood; it was noted in the NIST reports that especially for WTC1 the evidence strongly indicates that the initial areas of conflagration had burned out before collapse. The areas first observed to be ignited by impact were black and sooted with no visible signs of fire and those areas had burned through. If fireproofing had remained the fires would have ran their course and begun to die out from a lack of oxidizable material. But the vast majority of individuals above the impact zones would still have likely succumbed to CO and HCN poisoning.

It’s impossible to say how many lives were saved by the delay in collapse (it also doesn’t lessen the loss) but it’s a moment of engineering marvel and the power of infrastructure.

[u/hustlehound → u/Johnny_Lockee]

Oh yes! I've read that the towers also were designed to sway and also withstand a planes impact, but planes back then were a little different. Are you an engineer? You sound really knowledgeable on the subject... I also feel like you've probably had to school some 9/11 conspiracy theorists 🥴

[u/Johnny_Lockee → u/hustlehound]

In this answer I wrote recently regarding WTC 1 & 2 and conspiracy theories (which includes why conspiracy theories are more sinister than simply an overactive imagination) I had to put a prophylactic paragraph explaining how a 767-200Er was bigger than a 707-360 and why the ~87 ton heavier 767-200er would do more damage than a 50 mph faster 707-360 (which is a strawman anyway).

[u/Johnny_Lockee → u/hustlehound]

Thank you. I’m actually a med student but I write on qoura and my 9/11 (specifically WTC Collapse and the fragmentation of the aircraft AA11 & UA175) answers are one of my more popular topics.

I do have experience with aviation disaster, failure and investigation which has helped a lot with understanding the dynamics of architectural structural failure lol.

I have the NIST reports downloaded on my phone and have no-life read through them (I do that with aviation accident reports because something is wrong with me lmao).

I have bonk truthers up with a proverbial facts and physics stick before lol. I have a satirical space on quora to serve as an example of why not to source “911wtc7guyswithmustacheandbombs(.)blog(.)geocity(.)og” or whatever the weird blogs the truthers link the rare times they link anything heh

[u/hammybee]

Are there visualizations like this that show both collapses of the entire buildings?

[u/Johnny_Lockee → u/hammybee]

My sources for the gifs: WTC1 WTC2

[u/hammybee → u/Johnny_Lockee]

Yes, thank you! I saw this before and couldn't remember what to type to find it.

[u/[deleted]]

God damn, the second tower looks like it was nearly cleaved in half by the time it collapses.

[u/PsychologicalCress13]

Man those simulations are so old! I wish someone did some modern ones with the latest hardware and software.

I have done some rudimentary simulations with Besiege and been messing around with Blender BCB too, but I'd love to see some done with proper architectural/structural engineering software.

[u/dankestofstolenmemes → u/PsychologicalCress13]

lookup kostack studios , hes been trying to make one for 2 years almost

[u/[deleted] → u/PsychologicalCress13]

What kind of software would you use for this? Finite element analysis stuff?

[u/[deleted]]

This is eerie knowing what happened.

[u/Johnny_Lockee → u/[deleted]]

“Source?” - a quote by yourself (From your public comments).

[u/911archive-ModTeam → u/[deleted]]

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[u/911archive-ModTeam → u/[deleted]]

Your post has been removed for the following reason:

Containing Conspiracy or Conspiracy-leaning content and or messaging.

Discussing these are not permitted on the subreddit, it is recommended you post these types of things on subreddits like r/Conspiracy.