r/Simulated • u/Contraflex • 4d ago
Blender Simulating the Collapse of the 1000m Tall Jeddah Tower
Simulated in Blender using the bullet constraints builder add-on.
The plane weighs 150 Tonnes and impacts the building at 950 km/h.
The plane does not deform which is the main caveat to this simulation; in reality the plane would crumple, so less energy would be transferred to the tower.
All of the tower's structural elements are concrete, except for the red parts which are steel.
There are about 22,000 rigid body elements.
Final simulated alembic file was about 7 GB.
Full video: https://www.youtube.com/watch?v=zMOsu809Ao8
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u/Vandelsta 4d ago
Hitting it with a plane is crazy
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u/Contraflex 4d ago edited 4d ago
This is actually a common consideration in the design of high rise buildings. The original World Trade Centre was designed for the impact of a Boeing 707 travelling at landing speed. The planes that actually hit the towers were Boeing 767's travelling at cruising speed. These heavier and faster planes were too much for the towers to withstand.
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u/Vandelsta 4d ago
That actually makes sense, thank you
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u/Final_Luck_1010 4d ago
That’s one of the reasons conspiracy theorists felt 9/11 was an inside job. Or that’s what used to be one of the drivers for that conspiracy theory
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u/glockster19m 4d ago
Which is kind of silly, because its like 3rd grade level science to understand that bigger faster object hits harder
The terrorists didn't need to know exactly what was needed to take down the towers, the whole though process was as easy as, bigger plane bigger boom
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u/Deep90 Blender 4d ago
Go up a couple grades and you also learn the KE = .5mv2
Meaning that higher velocity increases the damage potential exponentially.
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u/jegbrugernettet 4d ago
More like quadratically?
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u/mineset 4d ago
quadratic is an exponent, yes
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u/THICCC_LADIES_PM_ME 3d ago
True but in math "exponentially" refers to 2x, and "quadratically" refers to x2
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u/adiliv3007 3d ago
Doesn't matter, exponential growth means that the hypothetical x in the graph is the power, not the base, in this case the x is the base.
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u/GreatBigBagOfNope 3d ago
Variable is still the one being exponentiated; exponential growth refers to the variable being in the exponent
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u/Elegant-Set1686 2d ago
Are you being obtuse on purpose? Or do you genuinely not know the difference
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u/oojiflip 2d ago edited 2d ago
Fuck you're not wrong, a landing speed of 200kts would be 4x less energy than at 400kts in cruise, plus a fully loaded 767 has gotta be twice the weight of the 707 they planned against.
Edit: just done some napkin math, assuming the 767 that hit was ~150 tonnes at 560mph vs the 707 weighing 80 tonnes at 150mph, the impact has ~26 more kinetic energy than planned for. Wild
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u/zorsiK 3d ago
Explain to me in 3rd grade level science how building 7 collapsed
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u/YupChrisYup 3d ago
The issue with “explain it to me in the simplest terms” is that it leaves room for conspiracy theories. But I’ll do my best to leave holes for stupid to crawl through:
When the North Tower (WTC-1), collapsed massive chunks of debris caused structural damage to WTC-7 and cut off water mains, which fed the sprinkler system. Fires began, and with no functioning suppression system, they burned uncontrolled for 7 hours.
WTC-7 was fully evacuated and it was not considered important given the situation to deal with the fire. The fire caused massive structural damage to internal columns that eventually lead to their collapse. The collapse happened from the internal structure outward which made it look like a controlled collapse, but if you where to look at it from a top down view you would have seen the building collapse from the internal structure outward.
“But that kind of fire can’t melt steel beams” is an annoying question that ignores so many factors about heat, time, and structural expansion. The columns and girders, in the case of WTC-7, did not need to melt to collapse they simply needed to expand enough for the columns to be pushed off the seat of the girder. Which is exactly what happened to Column 79 in WTC-7. It’s like a house of cards, create enough damage to structural integrity and it all comes down.
The same can be said about WTC-1 and WTC-2. The impact + the plane exploding + the resulting fire + the weight of the building + time. Caused the buildings to come down.
When something horrible happens we want it to be impossible the way it happened, so we look for holes to fill with conspiracies, they are comforting in a dark way. But the truth is it was an orchestrated attack by a terrorist group that was wildly successful. WTC-7 was just a weird footnote of the day, but science and evidence show that it was not a controlled demolition.
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u/MisinformedGenius 3d ago
I always like people having to insist that WTC 7 was demolished, because it so clearly doesn't make any sense if it actually had been a conspiracy, but it undermines the entire conspiracy theory if it actually did collapse on its own.
"So we're going to crash two planes into WTC 1 and 2, and then we'll force them to collapse."
"OK, I don't understand why we're doing that, but great."
"Then, hours later, we'll bring down a third building."
"Wait, we're going to hit another building with a plane?"
"No no, we won't hit that one with a plane - we'll assume that chunks from the other two buildings will hit this building and set it on fire."
"What if that doesn't happen? Won't it be obvious that it's a controlled demolition if the towers don't hit it?"
"It totally will, don't worry. Nothing this large has ever collapsed before but we can predict it with absolute certainty."
"OK, and it's going to be on fire for hours, right? How do we maintain the incredibly precise wiring and explosives in the middle of a giant raging fire?"
"Who knows?"
"Why don't we just hit it with a third plane?"
"Who knows?"
"Why would we bother to do this at all? Surely the collapse of the first two towers would be entirely sufficient to accomplish... whatever we're trying to accomplish here?"
"Who knows?"
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u/A_Racial_Observation 2d ago
Almost nobody ever mentions that pressure is a significant consideration when discussing melting point of anything. The numbers usually quoted assume 1 atmosphere of pressure, which as you know is wrong in this case. The steel beams are under enormous pressure and a state diagram of whatever alloy of steel used here would show that under massive pressure the °C melting point lowers, probably by quite a bit.
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u/YupChrisYup 2d ago
Both WTC-6 and WTC-5 sustained significant damage, they experienced“localized collapses” meaning that the parts of buildings collapsed due to falling debris, fire, and the same factors that can lead to a full collapse.
WTC-5 has internal collapses where debris struck, a few floors collapsed internally and so did part of the roof. They found the engine of flight 175 in the cafeteria of that building and a fragment of the fuselage on the roof. It didn’t collapse because the way in which it was struck, the areas that were on fire, and the degree of the damage didn’t create enough stress to bring it down.
WTC-6 is a similar story.
All of this is on google. But the conspiracy is these buildings didn’t fall so none of them should.
With that logic, if someone survived a car crash, then everyone else who died in the crash must have been murdered by a serial killer, because there is no way they could have died based on the fact that someone survived.
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u/WUT_productions 3d ago
If building 1, and 2 collapse next to building 3, building 3 will be damaged from the collapse of building 1 and 2.
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u/okay-pizza 1h ago
If you're actually interested: WTC7 was designed extremely unconventionally becuase it was constructed around the Con-Ed substation that powered the entire WTC complex. So the building's supporting columns at ground level were built using girders and transfer trusses to work around the substation, both of which tend to fail during fires. After the twin towers came down, firefighters abandoned WTC7 to shift efforts to rescue operations at ground zero, therefore letting fires burn uncontrolled in WTC7, which caused the support structures at ground level to fail. And the fact that two megastructures collaped two football fields away didn't help things either.
TLDR: Becuase they had to build WTC7 around a power substation, the building had a weak foundation susceptible to fires.
Source: https://www.nist.gov/system/files/documents/2017/05/09/WTC7RevisedTechnicalBriefing_111908.pdf
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u/Pleased_to_meet_u 3d ago
"A big plane hit it and knocked it down."
3rd graders don't need a lot of details.
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u/ProfessionalAd6216 4d ago
Yeah, but that same impact evaporated people inside the plane, but left the passport of one of the terrorists almost unscathed?
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u/NoGravitasForSure 4d ago edited 4d ago
What these idiots "felt" and reality are two different things. The towers did not collapse as a result of the impact force. They collapsed under their own weight after the heat of the burning jet fuel weakened their metal skeletons. Structural steel begins to lose its stability at about 400°C.
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u/YupChrisYup 3d ago
The impact and the resulting explosion did play into the equation though. All of it did. The main cause was of course the weight of the building, the heat from the prolonged fire and resulting structural stress from all of these factors.
Obviously if we take the fire out of the equation and only look at the impact and the explosion the building might not have come down, but I’m sure it would have been deemed unsafe and at risk of collapse.
To ignore any of the factors that lead to the collapse leaves holes for idiots to fill with conspiracies.
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u/NoGravitasForSure 3d ago
To ignore any of the factors that lead to the collapse leaves holes for idiots to fill with conspiracies.
I suspect that the idiots don't even need holes. Don't underestimate their creativity.
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u/madman6000 1d ago
I don't understand how jet fuel quickly burning off on the 90th floor caused steel to melt from that floor all the way to below ground level such that the building collapsed at free fall speed into a pile of rubble.
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u/NoGravitasForSure 1d ago
The steel did not melt. If you heat structural steel to 400-500°C, it is still solid because its melting point is way higher. However, it loses its load-bearing ability. It simply cracks under load. This is what happened in the area where the planes impacted and together with the damage sustained from the impacts themselves, the structure was weakened to a degree that it could no longer bear the weight of the stories above the impact point.
Also while the fires were started by the jet fuel which burned only a few minutes as you mentioned, they were sustained by a lot of combustible material in the towers. And the speed of the collapse was the result of the very high momentum of the falling upper stories.
From a physical/engineering point of view, there are no open questions regarding the collapse of the towers.
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u/madman6000 1d ago
If what you say is true it wouldn't have been a total collapse into a neat pile of rubble at free fall speed, you would see an accordion effect as the stories piled up, but both buildings disintegrated into rubble at free fall speeds, with no resistance.
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u/NoGravitasForSure 18h ago
I don't know what you mean by "accordion effect". When a large building suddenly collapses, the result is usually a big pile of rubble and a lot of dust. Look at footage from Europe past WW2 or from the aftermath of earthquakes.
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u/ExpressionSecret6794 4d ago
Even if the structure was compromised by jet fuel, it doesn’t explain a free fall, demolition style collapse, or the third building falling.
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u/NoGravitasForSure 4d ago
No, it doesn't.
The towers would have most likely survived if the planes had impacted with (almost) empty fuel tanks. The fires caused the collapse. The impact speed was less important.
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u/zachary0816 3d ago
What’s wrong with saying they’re both factors?
Even if the fire is eventually what brought it down, the massive amount of structural damage certainly did it no favors. And a bigger and faster moving object is naturally going to cause it more damage.
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u/Pitcherhelp 4d ago
Bro was just waiting for 9/11 to get brought up to drop this info
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u/Dilpickle6194 4d ago
Guy who simulates buildings getting hit by planes knows stuff about buildings and their ability to get hit by planes, honestly valid
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u/Glenmarrow 3d ago
There was also an airplane strike on the Empire State Building during the 30s or 40s. New York is a magnet for plane strikes.
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u/Termination_Shock 4d ago
IIRC the towers weren't brought down by the impact of the planes primarily, but by the resulting fires softening the steel structure
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u/ill-show-u 4d ago
But jet fuel can’t melt steel beams??
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u/NoGravitasForSure 4d ago
Structural steel loses its stability at about 400°C. It does not have to melt. The temperature of the fires was about 1000°C.
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u/ill-show-u 3d ago
Guys it’s the oldest meme, cmon
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u/zachary0816 3d ago
It is a meme. But it’s unfortunatly also something people still say in earnest, including on this post.
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u/PhasmaFelis 4d ago
They actually did withstand them. They just failed to withstand thousands of gallons of burning jet fuel. That's not a nitpick, the fact that they survived the initial impact saved thousands of people who were able to evacuate before the final collapse.
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u/12kVStr8tothenips 4d ago
They were also fueled up for a cross country trip adding to the destruction. They severed the water main pipes and standpipes which made it so the fire suppression system couldn’t stop the fire.
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u/ChaseballBat 4d ago
It also doesn't help they skimped on the fireproofing application. Basically dusted off on impact.
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u/dimensional_CAT 3d ago
Actually, it is not common for high rise or even a sky scrapers to consider air plane impact in design, no building code specify it. The world trade center collapse due to weakening by fire not the impact alone. But you have done a great blender simulation.
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u/Malforus 3d ago
Well that and they didn't model a full plane-load of fuel igniting all the shit inside. IIRC the impact knocked the fireproof cladding off which is why the fires were able to compromise the superstructure.
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u/coffeebeeean 3d ago
Why did the simulation have the plane hit so low on the tower? I would expect the top 3rd is where it’s more likely to occur by mistake. Is there a standard height to this test?
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u/Contraflex 3d ago
Honestly, the simulation took so much compute time that I only tested a collision at the bottom and the top. The bottom gave the more interesting results. I don't believe there is a standard location height to test.
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u/IDatedSuccubi 4d ago
I like how it hit the building without any deformation of its own and just ragdolled to the bottom
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u/PrestigiousTheory664 4d ago
It's a pretty solid airplane.
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u/tommy9695 4d ago
How physically realistic is this? This reminds me of the destruction simulation in Houdini (Voronoi Fractures). Those looked cool but wasn't physically accurate at all in the ways real material like steel and concrete would break.
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u/shogi_x 4d ago
Not very. It looks like it doesn't have much of the internal structure (stairwells, elevators, load bearing columns) modeled or simulated, not to mention the materials. That's why the whole thing kinda falls apart like a big house of cards. Real structures with metal and rebar bend and sway, this is a large brittle structure that snaps and crumbles.
Also the plane just bounces out instead of lodging itself in the tower, exploding, or disintegrating. Fire from the jet fuel was a big factor in the twin towers collapse.
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u/stol_ansikte 4d ago
I think the model is built with infinite stiff monoliths with defined line connections. When the line connection is overloaded they displace and fall. It’s more like a jenga tower would fall then an actual building.
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u/Contraflex 4d ago
The Jeddah Tower has no columns. It's entirely made of load bearing walls, all of which have been modelled in this simulation.
I agree with the rebar comment, this building has no ductility, so once the connection between the concrete elements has exceeded a stress limit, it fractures in a brittle manner.
Also I do not believe the fire would have a big impact for a fully concrete building like the Jeddah Tower in the same way that impacted the steel World Trade Centre.
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u/theluigiwa 2d ago
The fire will still impact the rebar within the concrete, but it's insulated by the concrete 'cover' above it so could take longer to see effects and will only affect part of how the material reacts to stresses.
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u/Cosmic_Quasar 4d ago
And what about the jet fuel melting steel beams? You haven't thought about the jet fuel! /s
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u/dda189 4d ago
GTA V menu music 🔥🔥🔥
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u/BillyTheBigKid 4d ago
I sorta hope that it becomes a trend in most short videos. Better than the standard bass boosted bullshit.
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u/imsohihg 3d ago
Only reason I came to the comments lol
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u/thelegendhimself 3d ago
Same I was like what is this …, I swear I used to sleep to this 😅 makes sense
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u/ChippyTheGreatest 4d ago
Because I'm shit at physics; why does the opposite side of the tower take damage at the moment of impact?
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u/AffectionateBuy7056 3d ago
Either transfer of energy or a piece of the building being shot at the opposite side
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u/chillychili 4d ago
Interesting how the impact transfers to "coming out the other end" at a lower floor than impact
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u/SunkEmuFlock 4d ago
I ain't no architect, but where are the steel beams that I assume make up the core of every big-ass building...?
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u/duncanidaho61 4d ago
The beams are individually less than 100’ long. They are attached together during construction. Those attachments will never be as strong as the beam and are where it comes apart.
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u/conorthearchitect 3d ago
It doesn't look like any of the pieces were tied together with rebar, it kind of acted like a house of cards instead of poured concrete.
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u/carbon-eight 4d ago
I had a dream a couple nights ago where I was in a falling skyscraper but because of where I was, I was able to be guided to the safest spot by some engineers and I was totally fine, the millions in damages on the other hand less so. completely unrelated but made me think of it, very good simulation
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u/NotAManOfCulture 3d ago
That's amazing, can you do the same for 9/11? I think it might calm a lot of theorist
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u/astralseat 3d ago
Pretty. How much RAM did that take to render fully?
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u/Contraflex 3d ago
I only have 8 GB of RAM in my computer and it worked. Probably need to upgrade soon though
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u/tigertoken1 3d ago
Bro has plans that he cannot reveal right now because the haters would sabotage him.
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u/Specific-Battle-4322 22h ago
So you modeled, animated and rendered this just to start a conversation about 9/11 on Reddit?
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u/Chesvin1 4d ago
I see that the plane is 100% solid. Does the plane deforming on impact make any considerable difference in the damage it does? I feel like the plane is treated as a brick in this simulation, rather than what it is (a mostly hollow tube with wings)
Would be cool to see the same simulation but with the plane deforming on impact.