This link:
Has some data about the tallest buildings that exist today. The current #1 is Taipei 101, at 1667 feet. That’s pretty impressive. How much further is it possible to go, with current materials and techniques?
I assume there’s got to be some point at which the building is unable to support its own weight, or the sway from the winds is simply too much to handle…
There is not really a limit to how tall you can make a building. Weight and wind effects can be dealt with in engineering. The only limiting factor is really money. At this point you can build as high as you have money to pay for it.
I read somewhere (don’t you love answers that start that way?) that at a certain height, the pressure at the bottom from all the structure above will cause the temperature to rise above the melting point of any known material. That would put an upper bound on it, for sure.
But that height is some significant fraction of the earth’s radius, IIRC. I’m sure there are other limits to worry about before gravitational heating becomes an issue.
I’m sure they could keep reinforcing the bottom levels to withstand higher weights. At some point I imagine they give up because the lower levels end up being useless do to space required for the supports.
It also depends on the materials used. I read somewhere that if you could mass produce graphite fiber (like the kind used in tennis racquets, etc.) cheaply enough to replace steel as the load bearing material, you could build a skyscraper twenty or thirty miles high.
The main limits then are cost and practicality. A building has to resist being pushed over by the wind, yet if you make it too thick large amounts of volume will be buried deep inside the building with no window frontage, which is less valuable. As has been pointed out, if you have to devote almost the entire ground floor to support structures, you’ve done little other than build a pedestal for your skyscraper to sit on. And elevator access to the upper floors is an enormous headache in itself.
Other than spires which exaggerate the total height of the building, the economical limit with today’s technology seems to be a building with a highest regular floor at 1200-1300 feet.
Lets bring in the humble space elevator, much of the weight of the building is not supported by below, but by attachment to a countermass in space tring to ‘fling’ itself away from earth.
For space elevators we have a material right now that will work, caobon nanotubes are strong enough to support such tensions. Now we don’t know how to build such long sections of carbon nanotubes, and the main problem, even if we could easially make miles of the stuff, is though it looks like it would work when built, we have no flippin’ idea how to build the silly thing.
I’m pretty sure you misread this, because pressure does not increase tempature though change in pressure does cause change in tempature. What I think you may have read is either vibrations in the structure would cause enough change in pressure that it would cause any known material to heat up to the melting point (note the pressure has to be changing), or more likely the pressure alone is enough to liquify (or ‘plasticise’) any known material.
Since the OP uses the word “theoretical,” I’d have to say that there’s no *theoretical *limit. But there are quite a few *practical *limitations, other than engineering and financial. A big question is: How will the building be supported by the surrounding infrastructure? E.g., would midtown Manhattan be able to support a five-mile-high skyscraper, in terms of power, plumbing, waste removal, transportation, emergency services, etc. Some of these concerns are already on shaky ground, as it were.
If we build it too high, God might come and make us speak even more languages, or something.
Funniest thing I’ve seen on SDMB in a while.
Here, “theoretical limit” is still a pretty vague term. We could, say, chop Charon into little bits, and use all of its matter to construct a tower that is a half a million or so miles long. But then the earth’s gravity would become distorted, and we would either crash into the sun or fly away from it. And if an asteroid hit any part of it, the people that were in the portion above the impact would become stranded in space. “Houston, we’ve got one hell of a problem.”
But aside from that, the only real limit is that amount of matter and energy currently contained in the universe (or multiverse)
Nature has built as high as Mt Everest without using exotic material, so we oughtt to be able to do that.
Frank Lloyd Wright proposed a mile-high skyscraper in 1956.
Opinions are divided on how structurally feasible it was. The Wikipedia page mentions wind effects, which would certainly be substantial and probably not something that 1950s technology could have handled. Even with dampers the building is probably too slender to be sound. The real limitation was that it couldn’t be economical. And also, like most superhigh building proposals - Wright was certainly not the last to propose a mile-high building - it’s a sculpture, not a building one could easily work in.
Semi-hijack: I think I read somewhere that the height limit on skyscrapers wasn’t really it’s structural intergrity, but was rather other problems, like the water pressure needed to propel clean water from the ground all the way up to the top floor?
Other problems do come into being, water distribution isn’t one of them. A series of pumps would handle this effectively. One of the biggest problems is moving people around in these buildings, as elevators can only hold so many people. Some solutions are double cars, one on top of the other, sky lobies, where you take an express to a local, as it were. There has even been some experimentation on bypass cars so that two cars can occupy the same shaft.
I think you would surpass the compressive strength of the material before you got into a pressure heating kind of situation.
There is a physical limit as to the height since after a certain point, the skyscraper wouldn’t be able to support it’s own weight or would require most of the area of the lower floors to be dedicated to structural support (which defeats the purpose of building so high). I would guess the maximum would be about a half mile to a mile high using existing technology.
But mountains work by spreading the load - they’re much wider at the bottom than the top, so the compressive forces are lower. A standard skyscraper with vertical walls couldn’t be built as high as Mt. Everest.
Except that Everest doesn’t have any internal commercial or residential space.
Well, the Burj Dubai is currently being built to an estimated height of 2600 feet (the final height is secret). That’s pretty impressive, and isn’t the limit, I’m sure.
I don’t think the Burj Dubai folks believe you, since they are planning on going 750 feet past the limit you imposed.
To be fair, it’s entirely possible that the Burj Dubai is being built outside the constraints of what’s economic.
Well, I see your point. On one hand you could say that the same amount of office space could be built at less cost, so the building isn’t economic.
On the other hand, you could say that if the person paying the bills thinks it’s a good deal, it is de facto economic.