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I'll confess that I have a real issue with iron--it rusts quickly. In fact, the History Channel program Life After People constantly states that, left to its own devices, the iron that makes up a skyscraper's skeleton would have a standing lifespan of 100-150 years before rust weakens the skeleton into pieces.

Long ago, I asked a question regarding the construction of metal weapons without the use of iron at all. In the answers selection, many candidates have been suggested, and they are:

  1. Titanium Alumnide
  2. Nickel Superalloy
  3. Nickel Alumnide
  4. Stellite
  5. Tungsten Carbide
  6. Zirconium Carbide
  7. An alloy of Titanium and Tungsten

What makes this list relevant to the question is that steel or any other kind of alloy had been used to make weapons before their use in construction, so the principle would be identical.

In an alternate, cyber-or-steam-punk New York, Chicago, Dallas or any of the United States' biggest cities, these listed metals and alloys had been considered for construction of mega-towers (a little like this or this or, if you want to go more historical, the artworks of Hugh Ferriss.) Using the science involved, which of the listed metals would be strongest in regards to tension, compression and resistance to corrosion?

Oh, and before anyone asks, this question stresses on quality, not quantity.

JohnWDailey
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    Many of alloys in your list are used for tools: they resist compression and corrosion, but are brittle. A skyscraper do bend a bit by the wind (and potential earthquakes), tungsten frame will crack. Since you want resistance to corrosion and structural stability, consider the marine alloys, e.g.: https://www.metalsupermarkets.com/marine-grade-metals/ – Bald Bear Mar 15 '18 at 19:16
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    Also, you should consider economics. Corrosion-resistant alloys are expensive. People who build skyscapers do not care what happens to them if they are "left to its own devices". They plan on having their buildings occupied by rent-paying tenants, climate-controlled and maintained. If building ever loses its tenants, it will be dismantled to make space for something else; the only reason to build tall (at least in US) is that land is expensive, i.e. lots of people want to have an office or apartment there. – Bald Bear Mar 15 '18 at 19:22
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    They reason that we use steel isn't because it's the best for tension (good), compression (good) and corrosion (pretty bad), because aluminum is as good or better at all three of these things. It isn't even just because of cost, because aluminum is almost as good as steel there. Rather it's because we don't make buildings only out of steel, rather we make them out of concrete and steel. And as it happens, steel works incredibly well with concrete because their thermal expansion/contractions rates are so similar, which means that the steel doesn't make fatal cracks in the concrete. – RBarryYoung Mar 15 '18 at 19:30
  • Here is a large monument that is plated with Titanium, and it remains shiny after 30 years in a polluted city: https://en.wikipedia.org/wiki/Monument_to_the_Conquerors_of_Space But I cannot find what is the frame made out of. – Bald Bear Mar 15 '18 at 19:34
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    Whats good for weapons isn't necessarily good for construction, which is why the steel used for weapons is different from the steels used for buildings (there are 100's of different kinds of "steel"). If cost is no object, then I would guess that you probably want some kind of Beta-Titanium alloy tuned to match the thermal expansion of concrete. This could easily have significantly greater strength than steel, yet weigh less than half. Of course it would probably be pretty expensive also. – RBarryYoung Mar 15 '18 at 19:58
  • There was a question few days ago about using ivory for skyscraper construction. Just a hint that some exotic materials would also do. – Oleg Lobachev Mar 15 '18 at 20:34
  • Some carbon compounds may be suitable for building skyscrapers. Not very steam-punk but quite suitable for cyber-punk :) There have been real world experiments to use carbon nanotubes for concrete reinforcement. It is not there yet, but carbon may become a replacemet for steel in some applications. – Congenital Optimist Mar 15 '18 at 23:32
  • Metals, why is always metals? Actually you should consider good old fashioned wooden buildings. Timber and wood is making a comeback as a construction material for tall buildings. If this was further developed and improved it could include skyscrapers. – a4android Mar 16 '18 at 01:10
  • @a4android Can wood withstand heights of two miles? – JohnWDailey Mar 16 '18 at 01:59
  • Two miles might be a big ask. Honestly I don't know. This URL https://www.seattletimes.com/sponsored/could-that-skyscraper-be-built-with-wood/ mentioned 997-foot tall skyscraper in London & other tall wood buildings. Wood construction technology is on the improve. Conventional skyscrapers appear to be within its reach. Combined with fullerenes & carbon nanotubes they go much higher. – a4android Mar 16 '18 at 07:25
  • World largest timber building will be 18 stories high and is being constrcuted in Norway, Expected to be ready in 2019. Current highest timber bulding in Norway is 49 meters, 14 storey high, – Congenital Optimist Mar 16 '18 at 08:32
  • @RBarryYoung steel and concrete's similar thermal expansion coefficients make them a great pair for things like roads and bridges, where the concrete is exposed to the weather. But there's not much exposed concrete in skyscrapers. – RonJohn Mar 17 '18 at 05:39
  • @RonJohn Incorrect. Many skyscrapers have exposed concrete. – user71659 Mar 17 '18 at 16:13
  • @RonJohn also, it doesn’t really matter, thermal expansion and contraction happen whether it is exposed on not. It happens slower if it is not exposed, but it still happens. – RBarryYoung Mar 17 '18 at 19:07
  • @RonJohn There’s also another reason that steel is preferred over aluminum, starting at around 400F, Aluminum starts to lose its strength and deform much faster than steel. This means that even moderate fires in an aluminum building could lose their structural integrity. Steel retains its strength up to 1000-2000F. – RBarryYoung Mar 17 '18 at 19:18

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If rust is the problem, why not trade iron for stainless steel?

A quick look at coefficients of thermal expansion suggests that you can get stainless steel with a similar coefficient to that of concrete, and because it's so similar to iron, you won't have to change your construction methods much, if at all.

walrus
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Researchers at MIT have used graphene to develop a lightweight material that’s 10 times stronger than steel that could potentially be used to manufacture vehicles and devices, as well as in building construction.

A team of researchers in MIT’s Department of Civil and Environmental Engineering (CEE) designed the 3D material—one of the most lightweight and strongest ever developed—by compressing and fusing flakes of graphene, a two-dimensional form of carbon. The result is a sponge-like configuration with a density of just 5% that is incredibly strong, they said.

Graphene, in 2D form, is believed to be one of the strongest of known materials, but its strength in the 2D world has been difficult to translate in a 3D material. Graphene has exceptional strength, but because of its extraordinary thinness, it is not very useful for making 3D bulk materials that could be used in vehicles, buildings, or devices without first translating graphene into three-dimensional structures.

The geometrical configuration of the is the dominant factor in their characteristics and the success in using graphene to design them.

Researchers developed the material by compressing small flakes of graphene using a combination of heat and pressure. This process produced a strong, stable structure with shapes that resembled some corals and microscopic creatures called diatoms

~credit: "designnews.com" and "MIT.com/CEE" respectively

Belqinor
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Why metals at all? Concrete and composite rebar (carbon fiber reinforced plastic, glass FRP, aramid FRP) construction is now used in structures such as bridges precisely because they do not rust, and are light. Such technology could be applied to concrete skyscrapers.

The same technology applies to truss structures. There is a clear path today towards replacing structural steel with composites.

user71659
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    Skyscrapers need the ability to sway in high winds. Concrete is poor at that. – RonJohn Mar 17 '18 at 05:50
  • @RonJohn And composites are even better than metals at swaying (cyclic stresses) because they do not fatigue. That's a huge reason why they're building airplanes out of it. – user71659 Mar 17 '18 at 06:07
  • Your answer is about concrete using composite rebar, not about buildings made of composites. And no one wants to be in a building that sways as much as a Boeing 787 wing bends. – RonJohn Mar 17 '18 at 06:19
  • @RonJohn Your comment about concrete is factually wrong. Multiple skyscrapers, up to 100 stories, are concrete. Please don't be mean-spirited and pedantic. Of course a skyscraper is not going to be built the same way as an airplane wing. Composites are a clear replacement for structural steel and other metals. Are you doubting that? – user71659 Mar 17 '18 at 16:05
  • composite rebar is a good choice but you should mention its limitations, it can't be joined by welding and has to be jointed with connectors meaning you have to stick to simple shapes, (no swooping curves for instance. and they breakdown under thermal loads as low as 200 degrees, so your buildings will be more prone to collapse in case of fire. – John Mar 17 '18 at 17:39
  • @John I think swooping shapes are fine, you'd just have to do it at the layup/molding stage when making the composite, rather than bending metal rebar on site (see carbon fiber bicycles). The problem with that today is of course how labor intensive design and fabrication tends to be. – user71659 Mar 17 '18 at 18:00
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    @RonJohn: I think you have it backwards. There's no fundamental need for a structure to sway in high winds. Rather, (and simplistically) buildings using steel-framed construction sway because the steel is flexible, so the building must be designed to handle that. At the opposite end of the scale, there are concrete dams up to 1000 ft/300 m tall, and I doubt they sway much. – jamesqf Mar 18 '18 at 01:32
  • @jamesqf to say that skyscrapers don't have to sway in the wind because dams don't is... insulting. – RonJohn Mar 18 '18 at 02:03
  • Also insulting is making such commentary whilst armed with such a poor understanding of composites, particularly how reinforced concrete works. – Harper - Reinstate Monica Sep 15 '19 at 00:08