Iron Alloy Could Create Earthquake-Proof Buildings 107
separsons writes "Researchers at Japan's Tohoku University designed a new shape memory metal alloy. The super elastic iron alloy can endure serious stretching and still return to its original shape. The scientists say that once optimized, the material could be used in everything from braces to medical stents to earthquake-proof buildings!"
So far removed from the original article (Score:5, Informative)
Original article, after following three backlinks: http://uk.reuters.com/article/idUKTRE62I4AE20100319 [reuters.com]
TFA short on details (Score:5, Informative)
Here's a page with a bit more detail. [metapress.com] These alloys are of similar composition to stainless steel and tend to have very high levels of Nickel and a little Chromium tossed in for good measure. Shape memory alloys work by utilizing a crystal structure phase transition that causes stress in the alloy to re-align which basically is responsible for the shape change.
Re:not they aren't (Score:3, Informative)
'Tell me when you see stadiums with concrete roofs."
What sort of stadium? I know of several marine life stadiums with concrete roofs. I can think of one in Florida, one in Washington, and one in Mississippi. I'm sure there are several in Oregon. In fact, the ENTIRE STRUCTURE for these stadiums is solid concrete.
Re:not they aren't (Score:3, Informative)
The largest concrete dome in the world is in a church about 400+ years old. It is large, but not even close tothe size of conventional buildings, let alone sports stadium. Concrete is great at some things, but not everything.
Most likely use for memory-steel would be as the internal reinforcement in concrete structures, similar to what they already do, just better.
Oh and there is something called pre-stressed (Score:2, Informative)
Re:Flexible concrete is better and we already have (Score:1, Informative)
http://www.physorg.com/news3985.html [physorg.com] Even the beams being put into bridges are concrete because they are stronger and lighter than metal.
Correction: Even the beams being put into bridges are bendable concrete because they are stronger and lighter than metal.
More on that Bendable concrete: "Essentially, the fibers create many microcracks with a very specific width, rather than a few very large cracks (as in conventional concrete.) This allows ECC to deform without catastrophic failure" http://en.wikipedia.org/wiki/Bendable_concrete [wikipedia.org]
But before Bendable concrete this is how things were done: There are 3 kinds of forces, Tension, Compression, and Torsion (twisting motion).
Concrete is not "stronger" than steel, it is simply better in compression than steel (it can support more weight). If concrete is in tension beyond the limit, it will break (suddenly and without warning). Concrete is reinforced with steel because the steel complements it. Steel shows signs of fatigue before it breaks when over its limit. Also with changing temperatures, both steel and concrete expand and contract at similar ratios.
Re:So far removed from the original article (Score:5, Informative)
Re:not they aren't (Score:3, Informative)
No, it won't be better. Think about why the metal is there. If the metal in the concrete is too flexible, the greater brittleness of the concrete will result in the concrete cracking and breaking due to the metal not providing sufficient support.
Re:Flexible concrete is better and we already have (Score:3, Informative)
That is wildly incorrect. Concrete is very usable in compressive members, and is used for a variety of reasons (cost being an extremely important reason), but none of the reasons is because it is stronger than steel. High strength concrete is defined by the American Concrete Institute as having greater than 6000 psi compressive strength. Concrete with 12,000 psi strength is used in structures requiring high performance, and represents a slightly higher strength than was thought possible in 1970. You can get concrete of 19,000 psi strength if you want to pay for it.
Regular dirt cheap time honored 1012 carbon steel had a strength of about 50,000 psi. Concrete is not stronger than that, eh? High strength structural steel is at least 80,000 psi. "Maraging" steel's strength is over 200,000 psi and up to 300,000 psi.
Strength to weight ratio is of course what matters, and here concrete looks considerably better because of its low density. In these terms it's close to so-called high strength structural steel, but doesn't even come close to something like maraging steel, and is outperformed by plain old 6061-T6 aluminum alloy.
Re:not they aren't (Score:1, Informative)
Well there was the King Dome in Seattle. As I remember the concrete roof was pretty hard to bring down when its time had come. I believe Seattle WA is considered earthquake country.