Speaking of “cool but impractical” designs:
I’m not sure if this ever got beyond doing the math, but Bucky fuller once designed a geodesic sphere that got lighter in relation to the surrounding atmosphere as it got bigger. He calculated that at a half mile in diameter, a one degree temperature increase would allow it to float like a giant glass balloon.
I wouldn’t want to be under that thing when(and it would eventually) the temperature equalized.
You contradict yourself here: We do have the technology, right this very moment, to make nanotube cables and diamond bricks. They’re still quite expensive, and so not used for much, but you do say that money is no object.
Yes, the Illinois, mentioned in the earlier thread: The Illinois - Wikipedia
You’ll have problems maintaining air pressure as you go higher. Elevators will have to pass through airlocks. You’ll need to pump compressed air into the upper floors. The walls and windows have to account for the pressure difference on the upper floors also.
The OP has made clear he is not talking about a functioning building, a 10 km artificial mountain with a 6 km high radio mast on top of it would fit his definition.
How tall could we make a building thats practical for people to work and live in and enter/exit it several times a day is a completely different question.
Didn’t seem that clear to me, or others in the thread. We don’t have to limit it to the minimal possible functional structure.
Sky lobbies. Sky lobby - Wikipedia
Very common now.
The OP’s question hasn’t been very clearly answered, he is asking for “tallest possible structure” with no mention of practicality as a working building, there is one quote with no cites that there is no limit due to materials engineering etc. I’d like to see that followed up.
Could we really build a 20 km high tower if it didn’t need to be a livable working building? It just needed to stand up.
Well, someone would need to build it. Construction itself introduces a few factors – in the extreme case, supplying breathing air to construction workers. At lower heights it would also need to be considered. In fact a large part of the designing process for a structure is designing the assembly process. The question is not just, “will it stand?”, but “how can we build it?”
Deep mine shaft elevators go very fast (faster than any building elevator.) But they say there’s a limit to the height of the lift (1 mile?) The earth’s rotation will begin to affect it. So the miners excavate laterally, and then sink a second shaft. Easier for a building.
Yeah, it’s more of a materials science question than anything else. If we limit ourselves to a static structure that has to entirely support its own weight, how high could we go before normal construction materials like steel, granite and concrete are simply unable to sustain the load? Could we build a tower 10 miles high? 100 miles high? 1000 miles high?
I think current ultra high performance concrete has strength of around 30ksi. Under self weight that would be good up to 5.5 miles, albeit without a factor of safety. You also would gain some strength because of the confinement, if you built it like a pyramid. However, if you go the mounding route, you risk pushing the crust down into the mantle, which kind of screws you up.
How about they go build on the moon for the lower gravity?
I saw, on TV, a building being built, in Dubai I think, by forming the structure out of concrete, the concrete formers just climbed the structure as the building grew. They needed gargantuan pumps to move the concrete up, but as each “layer” cured, the machine just climbed on top. I think the limiting factor was the pumping of the concrete, you would need increasing pump power and eventually you will hit the limits of what is possible.
I suppose a similar restriction would apply to pretty much any material, you need to be able to actually get it to the height you require on time for it to be used.
How deep would the foundations for a 10 mile building be? That would be one colossal hole.
The weight of the building would be inconsequential compared to mountain ranges, so the first thing is without merit.
As far as building on the moon, the entire point of a space elevator is to be able to get things into space cheaper and faster. How do you propose to get this much material to the moon? Or barring that, just get the men and equipment there?