By Sharka Todd
STEEL GIRDERS DISPLACE HEAT THROUGHOUT THEIR LENGTH
Steel is a very good conductor of heat. Therefore, when heat is applied to a limited area of a steel beam the heat is transferred away from site of contact which enables the steel beam to stay at a safe temperature throughout it's length. As a result it maintains strength and doesn't fail.
Therefore, a fire of a given temperature will not raise the temperature of a steel beam to that temperature, unless the whole beam is subject to the same degree of heat, which is highly unlikely given the limited nature of fire and the way it moves throughout a building- dying down here and flaring up there. This enables steel framed buildings to continue standing even during the most catastrophic of fire events.
So why did WTC1,2 and 7 collapse on 911? Simply, bombs in the buildings (likely combined with steel cutting charges).