I need a picture of a skyscraper made of aluminum for a science project. i have had such a hard time looking and i am yet to find a picture of a skyscraper made of mostly aluminum. can anyone find me a picture of a very tall skyscraper made of aluminum? thanks =]
I don't know that I've ever heard of a skyscraper made of aluminum. Although aluminum is almost as strong as steel (tensile strength), it's modulus of elasticity is about 1/3 that of steel, so it would tend to sway in the breeze about 3 times as much as a steel structure. And vibrations from earthquakes would be a real problem (more of a problem than it already is for steel).
Luigi's answer is broadly correct, but I would like to point out that a structure's natural vibrational frequency is proportional to √(k/m), where k is stiffness and m is mass. Aluminum has 1/3 the elastic modulus of steel, and therefore 1/3 the stiffness for an identically-shaped structure, but it also has 1/3 the mass of the steel structure. Its natural frequencies (ignoring aeroelastic effects) are therefore approximately the same. While aluminum can't get nearly as strong as the strongest steels, 6061 aluminum (a very common aluminum alloy) is just as strong as the typical A36 structural steel. They both have a yield strength of about 36,000 psi. So why not build a skyscraper out of aluminum? 6061 aluminum and A36 steel may be structurally comparable, but A36 steel is far cheaper. That's the real reason.
