Blackbird From United States, joined Oct 1999, 3436 posts, RR: 5 Posted (2 months 3 weeks 5 days 3 hours ago) and read 886 times:
Would a conical shaped building which progressively sharpens as the top is reached (Like a hershey's kiss -- not too sharp a cone on the bottom sharper at the top, also like a supersonic multi-shock inlet) be a good shape for a skyscraper of extreme height?
Phoenix9 From Canada, joined Aug 2007, 521 posts, RR: 0 Reply 1, posted (2 months 3 weeks 5 days 2 hours ago) and read 845 times:
This is a shot in the dark: probably a major engeenring headache otherwise we would have seen a conical shape for a skyscraper already! My guess is that center of gravity of a cone building at a large scale would be an engineering nightmare to deal with. Not to mention load bearing walls etc.
Blackbird From United States, joined Oct 1999, 3436 posts, RR: 5 Reply 5, posted (2 months 3 weeks 5 days 2 hours ago) and read 819 times:
Okay...
1.) Take a circular base
2.) Create a cone with a 65-degree angle (if you looked at it from the side it would look like an isoceles triangle with a 65-degree sweep back), and continue that angle up to about 45-50% of the tower's height
3.) Over the next 25-33-percent of the buildings height, the cone's steepness from 65-degrees to 80-84 degrees, and from that point to the top increases to around 84 or 85 degrees, which eventually sharpnes towards the vertical at the top.
Francoflier From France, joined Oct 2001, 1417 posts, RR: 3 Reply 6, posted (2 months 3 weeks 5 days 1 hour ago) and read 810 times:
I see what you mean, and I think it would be possible, but probably not as roomy and structurally efficient as a straight cone or pyramid. Arguably though, it could reach higher than those.
You'd have to be a mathematician and architect to determine whether that shape would give you more internal volume than a straight cone over the same surface footprint.
It would also be harder and more expensive to build it that way.
Unless your name is Dubai, and then you'll build it just for the heck of it.
Looks like I picked the wrong week to quit posting...
ANITIX87 From Switzerland, joined Mar 2005, 2285 posts, RR: 11 Reply 7, posted (2 months 3 weeks 5 days 1 hour ago) and read 785 times:
For example, when rubble falls from an implosion or when you drop sand, what shape does it take? A cone with circular base. This is nature's most stable shape.
So, in theory, a conical skyscraper should be very, very sturdy. However, there are many factors to consider...
AESTHETICS: Is the shape economical? Will the loss of floor space due to circular floor plans lead to less office space and therefore less revenue? Will the size requirements for the base (an stable cone must have a relatively large base, especially at extreme heights) be too large for a neighborhood, and prevent the construction of nearby buildings and other real-estate development?
STRUCTURE: The cone is clearly more aerodynamic than a broad-sided building due to its circular shape. It should also, in theory, withstand earthquakes better. However, I assume that, unless the exterior wall is load-bearing (reducing the amount of glass that can be used, and therefore diminishing its "modern" appearance) the interior layout of support beams will have to be quite complex, and may even have to differ from floor to floor to account for the diameter of each subsequent floor.
Just my two cents based on 3 years of Mechanical/Aerospace Engineering classes and three internships at a Structural Engineering/Architectural firm. I'm clearly not an authority, but I felt like chiming in.
Phoenix9 From Canada, joined Aug 2007, 521 posts, RR: 0 Reply 10, posted (2 months 3 weeks 4 days 18 hours ago) and read 692 times:
Quoting ANITIX87 (Reply 7): This is nature's most stable shape
Correct me if I am wrong...but nature's most stable shape is a sphere not a cone. Sand and rubber take a conical shape because they can not form a sphere under given circumstances (solid ground on one end). Examples of roughly spherical natural shapes: water droplets, planets, stars etc.
Pellegrine From United States, joined Mar 2007, 207 posts, RR: 0 Reply 14, posted (2 months 3 weeks 4 days 17 hours ago) and read 630 times:
Quoting Blackbird (Thread starter): Would a conical shaped building which progressively sharpens as the top is reached (Like a hershey's kiss -- not too sharp a cone on the bottom sharper at the top, also like a supersonic multi-shock inlet) be a good shape for a skyscraper of extreme height?
Not really sure what you mean by "a good shape" because today with modern engineering, a building of any shape can be made basically to any height (up to 1.5km+ maybe). The only considerations are the aesthetic desires of the owner and how much money they want to spend. Such a tower you describe will have a HUGE base, any conical structure does relative to it's floor space, especially relative to the upper 1/3 floors.
And actually, unless the outer facade is load-bearing, the structural advantages of a cone are lost, since it would basically be a building with gradual set-backs on each floor. So to retain the full advantages of the shape you'd need the facade to be load bearing, it could be similar to the destroyed WTC design really. With a load bearing exterior and a strong core, entire floors of the building could be made column-less...on the upper floors at least.
I have another idea for a client with bottomless pockets. With a circular shaped core you could make either the entire building or certain floors within the building turn. Stationary offices on 2-50F, condos from 51-70F, and a rotating hotel/restaurant/observation deck 71-85F? It'd be sick.
If any of those tall mega-habitaiton structures get built (housing 500k-1m people), it will probably be a fat cone or pyramid. Almost all of the proposals are that way.
...someone said something about the Peking Circus...
Blackbird From United States, joined Oct 1999, 3436 posts, RR: 5 Reply 15, posted (2 months 3 weeks 4 days 11 hours ago) and read 567 times:
Francoflyer,
Quote: I see what you mean, and I think it would be possible, but probably not as roomy and structurally efficient as a straight cone or pyramid. Arguably though, it could reach higher than those.
You'd have to be a mathematician and architect to determine whether that shape would give you more internal volume than a straight cone over the same surface footprint.
It would also be harder and more expensive to build it that way.
A straight cone or pyramid would probably be better structurally and volumetric-wise, however this shape would be able to reach to greater heights for the given ground area. It would also look sleeker, and one could even argue more conventional than a pyramid or cone (as it would be taller than wide)
Considering the building would be approximately 21,120 feet (4 miles) high, it's base would probably be a little over half the building's height (2 miles). This would have PLENTY of room...
Quote: Unless your name is Dubai, and then you'll build it just for the heck of it.
Actually the idea was to create a ridiculously high tower simply for the purpose of rivaling the large buildings in Dubai...
ANITIX87,
Quote: For example, when rubble falls from an implosion or when you drop sand, what shape does it take? A cone with circular base. This is nature's most stable shape.
I would have thought a sphere or dome would have been more stable actually, and actually I suppose it would be possible to start the design off as a dome-ish shape, which then blends into a cone which becomes sharper and sharper as you get higher up. It would probably resemble a Hershey's-kiss (or the D-21 drone's inlet).
Quote: So, in theory, a conical skyscraper should be very, very sturdy.
That was actually basically the question I was asking whether it would be a good sturdy shape, although I'm not sure I phrased my question right. I assumed it would because pyramids are, and a cone is the same but with a circular base.
Quote: Is the shape economical?
Well volume wise it would probably be superior to a regular cylindrical or rectangular shaped tower (Chrysler Building, Empire-State Building, WTC-1 and WTC-2, Sears Tower, Burj Dubai) of the same height as this tower would be so much larger at the base that it would compensate for the tapering of the building's structure further up. The building should be able to carry at least as many offices, apartments, and stuff as a more conventionally shaped tower.
Quote: Will the loss of floor space due to circular floor plans lead to less office space and therefore less revenue?
I'm not sure, but considering how large the tower is (4-miles high), and the size of the base base relative to the height when compared to a conventional tower, (and that the bulk of the office space, apartments and stuff, and such in the tower is in the lower 45-50 percent of it) even if circular would probably still exceed the total volume of a conventional tower design of the same height.
The circular corridor layout shouldn't be too hard to get used to. You would have a bunch of concentric corridors which go around the circumference, and radial corridors which extend from the inside towards the outer section of the building.
Quote: Will the size requirements for the base (an stable cone must have a relatively large base, especially at extreme heights) be too large for a neighborhood, and prevent the construction of nearby buildings and other real-estate development?
Probably yeah, unless you put all the real-estate and office space in the tower itself. The base of the tower is something like 2-miles or so around, with gardens and various things to occupy the rest of the property (you get land in blocks in a city) -- if the place did have a lot of apartments for people there could be playgrounds on the land available outside the tower for families with kids.
Quote: The cone is clearly more aerodynamic than a broad-sided building due to its circular shape. It should also, in theory, withstand earthquakes better. However, I assume that, unless the exterior wall is load-bearing (reducing the amount of glass that can be used, and therefore diminishing its "modern" appearance) the interior layout of support beams will have to be quite complex, and may even have to differ from floor to floor to account for the diameter of each subsequent floor.
I was thinking of using both external and internal supports to provide a great deal of structural redundancy with the building designed to withstand stresses many times greater than what would ever be experienced during it's existance (which should be as long as possible) both internal and external, including earthquakes, fires and other such problems. The building should also be designed with all the lessons from 9/11 learned, including provisions for multiple large, high-speed aircraft collisions (building is over 20,000 feet tall and the 250-kt speed limit goes away at 10,000 feet) and ensuing fireballs to go with it, with the building potentially constructed with "shear-zones" which allow damaged sections of the tower to simply shear off and collapse away from the structure avoiding further harm to the rest of the structure (so if one area, god forbid, collapses, it doesn't take the rest of the building with it).
Now since all these structural requirements are extroardinary, and despite this, the building should also have a modern appearance, some advanced materials might prove useful in the design of the structure which are lighter including...
-High-strength, corrosive resistant metals
-Perhaps using various metallic-foams (URL: http://nic.sav.sk/ummsjk/main_act.htm )[/i] in some structural members in order to provide good strength and weight-reductions.
-Composites
-Possibly Cabon Nanofibers
-A type of ceramic-transparancy (which oddly had aluminum in it -- no Star Trek jokes please -- which is currently used by military vehicles as a form of weapon resistant glass, which probably would have good load-bearing qualities and could double as windows in appropriate areas)
While not related to structural-integrity, the design IMHO should incorporate "Green Appeal" -- The building could also be covered with these new photo-voltaic glass panels (preferably these multi-spectrum type which are more efficient, though current designs should do -- they are partially transparent and can cover over the window-panes) which would allow the tower to at least reduce it's overall power bill by generating some of it's electrical current via the sun, either that or it could power a lot of area nearby.
Quote: Just my two cents based on 3 years of Mechanical/Aerospace Engineering classes and three internships at a Structural Engineering/Architectural firm. I'm clearly not an authority, but I felt like chiming in.
No worries. I like hearing input.
Nighthawk,
Well that design is more of a stretched-dome/bullet-shaped. The design I was thinking of had a cone with a pointed top. The slopes do become sharper as you near the top eventually reaching a point.
Phoenix9,
Quote: Correct me if I am wrong...but nature's most stable shape is a sphere not a cone. Sand and rubber take a conical shape because they can not form a sphere under given circumstances (solid ground on one end). Examples of roughly spherical natural shapes: water droplets, planets, stars etc.
I was actually thinking the same thing... would the structure fare any better if the design started off with a dome-ish shape which then blends into a cone which becomes sharper and sharper as you get higher up (Think Hershey's kiss, or a D-21's inlet)
Pellegrine,
Quote: Not really sure what you mean by "a good shape" because today with modern engineering, a building of any shape can be made basically to any height (up to 1.5km+ maybe).
When I said a good shape, I meant a shape that would be naturally sturdy and well suited for a very very large building. Granted we have engineering technology that can allow more ordinary building shapes to go higher, but I think it is wiser to go with a structure that just naturally tends to be sturdy -- while using modern engineering technology to enhancing it's sturdiness even further. After 9/11, I'd want to make sure this building was VERY, VERY sturdy and would basically need a nuclear explosion to take the damn thing out.
Quote: The only considerations are the aesthetic desires of the owner and how much money they want to spend. Such a tower you describe will have a HUGE base
That is correct, according to my estimates it would be like 2.0 to 2.2 miles -- it would essentially be an artificial mountain.
Quote: any conical structure does relative to it's floor space, especially relative to the upper 1/3 floors.
Any building does relative to it's floor space. The overall volume of the building due to it's shear size would allow it to carry enormous amounts of office space. More than any current building in existance to my knowledge.
Quote: And actually, unless the outer facade is load-bearing, the structural advantages of a cone are lost
The building as I conceptualized it would have a load bearing external and internal structure each able to hold the building up with multiple redundancies.
Quote: since it would basically be a building with gradual set-backs on each floor. So to retain the full advantages of the shape you'd need the facade to be load bearing, it could be similar to the destroyed WTC design really.
As I said, the building would have to be extraordinarily sturdy in a number of ways, and would have to be able to withstand many times any form of abuse it would ever take.
To deal with collapse, I have thought that one idea could be that the building could have "shear" zones that if a particular part gives way, it shears off without damaging the rest of the structure or causing it to collapse. That would require a particularly complicated set-up though and I'm not sure the logistics required.
[quoteWith a load bearing exterior and a strong core, entire floors of the building could be made column-less...on the upper floors at least.[/quote]
As I said, I'd prefer to use both interior and exterior supports.
Quote: I have another idea for a client with bottomless pockets. With a circular shaped core you could make either the entire building or certain floors within the building turn. Stationary offices on 2-50F, condos from 51-70F, and a rotating hotel/restaurant/observation deck 71-85F? It'd be sick.
I don't particularly like the idea much -- the logistics behind that would be extraordinary and would be even more complicated than need be.
Quote: If any of those tall mega-habitaiton structures get built (housing 500k-1m people), it will probably be a fat cone or pyramid. Almost all of the proposals are that way.
I've never heard of such a design. Is this designed like a super-apartment thing? What kind of people are behind this sort of thing (this isn't like to permanently isolate people away from everybody else is it?)
In either case, I have considered the idea of having large parts of this conical-skyscraper carrying apartment buildings of various sizes. With a 4-mile height and a 2.2 mile base, the building would essentially be a man-made mountain. Since the land needed to build the structure on would be squarish, you'd have room for gardens and even play-grounds.
ANITIX87 From Switzerland, joined Mar 2005, 2285 posts, RR: 11 Reply 16, posted (2 months 3 weeks 4 days 10 hours ago) and read 536 times:
Quoting Blackbird (Reply 15): I would have thought a sphere or dome would have been more stable actually
In space, yes, but on the ground, a sphere is, for obvious reasons, impractical.
Quoting Blackbird (Reply 15): I'm not sure, but considering how large the tower is (4-miles high),
I believe you mean 2 miles across, which makes it 6.3 miles around. That's just huge.
Quoting Blackbird (Reply 15): The base of the tower is something like 2-miles or so around,
There is a limit, at least in the USA, of 2000 feet high. Also, a 4-mile high building would weigh so much that it may be uneconomical, or even impossible, to create sufficient foundation support. There are also airspace interference laws, and the fact that the right to build upwards in cities is often more expensive than land-space, and also usually involves some sort of bonus project to benefit the city (a subway bonus, for example) which adds to the cost.
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