Quote Originally Posted by Renton View Post
afaik the beams didn't melt, they were just weakened by heat, which happens at well under the melting point.
I doubt that any steel I-beams melted clean through. The question as to whether ANY steel could be melted is what I tried to answer.

I tried to make the point about the reduction in structural integrity due to simply heating the steel. How's this for a practical example:

Consider sword making. The blacksmith heats the steel so that it is glowing a reddish-orange color due solely to its own temperature. This puts the Steel in a temperature range close to 1,500 - 2,000 C (based on the observed color, so wide error bars). When the steel is this temperature, it is weak enough to be shaped by the blacksmith.

I bring this up to help you understand in an intuitive way that the steel doesn't need to be heated to melting in order to have significantly lower structural rigidity.


Another factor is the loading. As one structural element weakens or is deformed, it displaces that stress to nearby structural members. These members which take on the new load are now more likely to fail, since they are now closer to their max loading. This can cause a chain reaction through a rigid structure.

Quote Originally Posted by Renton View Post
And the molten metal that conspiratards were talking about wasn't steel, but aluminum, which has a lower melting point than steel, i believe.
Disclaimer: I'm not researching conspiracy theories on this and the wackos who latch onto the path of "IDK -> it must be" with no steps in-between.

Confirmed that Aluminum has a lower melting point than Steel. Aluminum cans can be melted in most camp fires, as any beer-swilling camper can affirm. Steel cans don't usually melt in a normal campfire, but you can certainly do it with a little knowledge about air-flow. Something like a Dakota fire hole can be used to allow controlled oxygen feeding to the fuel, and a rudimentary blast furnace can be implemented in this way.

A Dakota fire hole is basically a U-shaped hole in the ground, with fuel in one hole, and nothing in the other. The empty hole provides Oxygen feeding to the base of the fire, keeping all the air flow through the combustion chamber moving upward. This 2nd hole can have a fan or bellows placed over it to make a simple blast furnace, increasing the combustion rate.