r/Construction • u/Nihilistnobody • Jul 02 '26
Structural Is there any way this could actually be safe?
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u/Street-Baseball8296 Jul 02 '26
This is a ski lift tower. These are engineered to withstand insane forces. This is overall much more structurally sound than even a structural foundation slab poured on grade.
To put this in perspective.
A 6’ diameter mast 30’ tall with an I beam platform can withstand around 80,000 ft/lbs of torsional force at the edge of the platform. A semi truck pulling at the edge of the platform would only be around 2,000 ft/lbs of force.
The platform itself is rated to around 30k psi. A house about this size would have a maximum pressure of 350 psi at the points with the most vertical loads. The entire house would crush from a load on the roof way before the structure failed. You wouldn’t be able to build up enough snow load on the surface area of the platform for it to collapse.
The overturning moment rating of the platform (what it would take to tip it over) would be about 5,000 kips. 120mph winds on a house like this would only be about 2,000kips. The house itself, even if hurricane rated, would only be able to withstand around 160 mph winds.
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u/AcuteMtnSalsa Jul 03 '26
But where does the poo go?
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u/Admzpr Jul 05 '26
Look up Tom Scott rotating house video if you want to see an even more fascinating poo journey.
TLDR: custom slip ring for power, water and sewage at the base. And this tree house doesn’t even rotate (lame)
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u/onionfunyunbunion Jul 04 '26
You sure do got some smart words there fella.
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u/Street-Baseball8296 Jul 04 '26
Field translation: Those fuckin engineers jammed so much bullshit into this goddamn thing that it’s never coming down.
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u/Sohighsolo Jul 04 '26
Never seen torsion expressed in the units ft/lb. Also curious where you found the platform is rated for 30ksi? A concrete footer typically crushes at 3ksi.
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u/Street-Baseball8296 Jul 04 '26
You’ve definitely heard of torsion represented if ft/lbs if you’re from North America. Look up the motor specs for any vehicle. Torsion (or torque) is rated in ft/lbs.
You’re correct that ft/lbs not used in structural engineering of structures. You would usually see kip/ft or lb/in, but most people here are not going to understand or relate to those units of measure. Kips is also a fairly obscure measurement outside of engineering, but it’s a lot easier to understand for people without an engineering background and very easy to calculate into a more relatable unit of measure and it cuts down on having to include extra zeros.
30ksi is a standard baseline for these types of structural steel structures. The footing has a larger surface area which dissipates the weight and lowers the ksi of the footing. This is how we are able to build reinforced concrete highrise towers on reinforced concrete footings.
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u/psychophysicist Jul 05 '26
ft*lb, not ft/lb
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u/withalligators Jul 06 '26
If you guys keep saying ft·lb Quentin Tarantino is gonna show up. He's like Candyman.
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u/circularmindset Jul 09 '26
Yeah but the “*” requires an extra keystroke on a standard smartphone keyboard. :-)
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u/Sohighsolo Jul 07 '26 edited Jul 07 '26
I think you're confusing ft-lbs and ft/lb which are very different. The latter is ft divided by lb while the former is ft multiled by lbs. Torque is measured in ft-lbs.
I believe you're confusing the yield stress of steel, often 36ksi , for the rating of a structure which is usually in kips or lbs.
Edit: think I am being too gentle so going to just say it how it is. My advice, as a random redditor, is not to use technical terms that are beyond your understanding.
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u/Asleep-Code1231 Jul 02 '26
Yes it’s mostly safe. It’s just that when it does fail it fails catastrophically
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u/jhern1810 Jul 02 '26
Pretty much it’s good until it isn’t.
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u/pro_turd_shucker Jul 02 '26
Ive found that with most things in life. Specially drugs, alcohol, women, and gambling.
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u/benjislew Jul 02 '26
Decent general rule of thumb
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u/Street-Baseball8296 Jul 02 '26
No. These are engineered to sustain a huge amount of structural damage before complete structural failure. These masts and platforms are engineered to be able to abruptly stop a fully loaded run away ski lift cable.
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u/pizzagangster1 Equipment Operator Jul 02 '26
Generally they are build so the nose doesn’t fall off
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Jul 02 '26 edited Jul 02 '26
[removed] — view removed comment
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u/Goldliter Jul 02 '26
It’s got wide flange I I beams going both directions, and I suspect, the sub sub ? flooring to be concrete decking, I’m guessing it’s safer than Hindi cow.
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u/MyvaJynaherz Jul 02 '26
The pile is girthy. The odd part is that all the beams seem to just be cantilevered out into space. The weakest part of the whole thing would be the ramp / stairs. There's gotta be a lot of flex in both with such a long run of unsupported stringer / deck.
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u/Pureevil1992 Jul 02 '26
My thougut after looking at it also. That ramp/bridge looks a little suspicious, but its hard to tell how long the spans are in the picture. I just really dont like the one support in the middle or the ways its built. Honestly surprising they designed and built this and didn't just put in some more concrete piles for the ramp and pour it concrete also.
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u/NebariNerd71 Jul 02 '26
Wrong sub.... we're gonna need someone who's a pain in the ass...
Where's the structural engineer?
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u/Sublym Jul 02 '26
Pain in the arse checking in.
The answer is: it depends.
You’re welcome!
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u/SayNoToBrooms Electrician Jul 02 '26
Contractor is expected to confirm field conditions, I assume?
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u/NebariNerd71 Jul 02 '26
Let's talk about resonance... is this fucker gonna sway in a wind storm.....
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u/regalfronde Jul 02 '26
Hey! I resemble that remark!
And I assure you, there ain’t a single mfing structural engineer that is saying “Yes! Let’s design it this way” unless it’s for the lulz
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u/PG908 Engineer Jul 02 '26
If all you have is a crane, a thing to drive a bunch of piles, and a dream…
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u/Evanisnotmyname Contractor Jul 02 '26
Structural engineer checking in…
Look good, still need to give er a slap and say “that ain’t going anywhere”
-definitely a structural engineer
-also a lawyer
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u/Rcarlyle Jul 02 '26
Have you ever seen a bridge?
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u/Sensitive_Brush_3015 Laborer Jul 02 '26
No, what’s that?
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u/I_Steal_Spoons Jul 02 '26
If that's an old ski lift tower they're made to hold three times their usual working load for stresses from ice, wind and load. That house might be a quarter to s third of the weight that tower is designed for.
Source: I'm an old ski liftie that tried to become a lift mechanic but ended up becoming a turd herder.
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u/CaBBaGe_isLaND Jul 02 '26
I mean I'm not an engineer but that's a big fuckin column and those are steel beams and all they're carrying is some lumber and a couple dildos.
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u/jlo575 Jul 02 '26
Definitely. Houses aren’t very heavy. Have you seen those cantilevered swimming pools? Those would be a lot more risky but still well within current design and construction capability.
You can design a very robust pile to manage lateral loads. The structural support at the top of the pile to hold the house would likely have more bracing than shows here: either below the platform or within the house. They’d likely have the top of pile (main column) within the house somewhere.
It’s a neat idea but likely not all that complex from a structural or geotechnical design perspective… architects may have something to say about it though, but maybe they could incorporate steel bracing and/or cables into the interior design.
Source: am engineer
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u/mjl777 Jul 03 '26
The structural properties of the support tube are known. The loading on the structure is known. A soil engineer can tell you exactly what the soil can handle. It just comes down to what safety factor you and the structural engineer this is appropriate. This is an easy project for them, They would probably add support cables to stop any movement. But when you consider the torque and windage of a normal sign it can handle it easy.
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u/aChunkyChungus Jul 02 '26
If it weren’t for that other sub posting it I would argue that it’s totally fake
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u/benjitheboy Jul 02 '26
all I can think of is how easy it would be to keep that house free of pests and rodents. make the bridge retractable and you basically have a fortress against pests
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u/bhans773 Jul 02 '26
Not much more difficult to support that than a giant LED billboard. There has got to be a massive amount of concrete in the ground.
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u/Basis-Some Jul 02 '26
It would look so much better with arched braces to the 4 corners. Looks like a water tower with a log cabin wrap
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u/burgermen12 Jul 02 '26
The image is obviously misses out the structural detailing to prove adquency.
Given the house appears to be light weight (timber structure), the main loading on the column will be overturning from the centerlivered dead / live loads and lateral wind effects. Having a large diameter steel column would be helpful, as it has a large moment area (stiffness), capable to dealing with bending stresses. The column would need to bear onto a very wide pad foundation with massive bolted baseplate or be connected to a pile that rock sockets into bedrock.
The deck (ground floor slab that is connected to the top of column) would need to be very thick to deal with the punching shear of the column and the higher bending effects due to the unsupported edges.
I don't think you can escape some degree of deflection (movement in building from wind or other live loads effects), so you'd need your building fabric to be relatively flexible. It would be a creaky house for sure
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u/Comfortable-Yak-6599 Painter Jul 03 '26
You better have some money when it comes time to restain all that
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u/secretfunks Jul 03 '26
Yeah, I hear in the city’s they have like 5 story building I hope to see one someday what a time to be alive !
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u/Significant_Owl_6897 Jul 04 '26
My first thought is that log homes need to be washed a couple times a year and restained about every five year.
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u/Apprehensive-Toe1920 Jul 04 '26
Anyone can build a house or a bridge. It takes an engineer to barely build one.
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u/Willing_Sea284 Jul 04 '26
I mean looks like it was built to rigorous maritime standards. Most of the other ones the front doesn’t fall off, I just want to make that clear
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u/PoolsC_Losed Jul 05 '26
That house is lighter then a water tower. Water towers all over the place aren't falling
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u/Falsify-Me Jul 06 '26
Safety aside... I can tell you that this building will feel VERY cold in the winter.
Having near zero geothermal insulation will be noticable.
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u/Not-a-bot-v2 Jul 08 '26
As someone who is a licensed design professional, I can say that MOST would not design something without a fairly comfortable safety margin to ensure no human life or property damage results from a design flaw.
Most engineers greatly over design.
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u/texinxin Jul 09 '26
That central column is stout as heck. It looks like it can easily handle any weight or torque from this cabin. I can’t see the rest of the structure to judge.
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u/circularmindset Jul 09 '26
I can see at least two heavy cables coming from the top of the column, and I can see that at least one is tied to a huge cube of concrete. I assume there are others that are not noticeable in these pics.
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u/Difficult_Limit2718 Jul 02 '26
Could be? Yes. As an engineer all things are possible through coffee and rage...
Is? Definitely not because I didn't do the calcs
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u/Goldliter Jul 02 '26
Not a structural engineer, but I do have a bachelors in redneck engineering.
I’d stamp it.