To refute that particular argument; steel may not [i]melt[/i] until it reaches 2700 degrees Fahrenheit, but it will lose a significant amount of its strength at far lower temperatures. Remember, "melting" implies the steel is entirely liquid. You'd surely agree that a warm hot dog will deform much more easily than a frozen one, even though they're both solids. Steel classified as "Structural Steel" is designated with a "Critical Temperature" which is the temperature at which it can no longer support the weight it's stated to. This is usually determined as the point at which the yield strength (the amount of stress a material can endure without deforming) drops down to 60% of the strength it has at room temperature. This value varies based on the type of steel (steel is an alloy of carbon and iron, so different concentrations of those, and even the temperature/speed at which they are heated and cooled can have huge changes on their material properties), but in the US, most structural steel has a Critical Temperature between 1000 and 1300 degrees Fahrenheit, a range within the range you gave for burning jet fuel.