Building fires typically don’t get hot enough to melt structural steel columns, even relatively thin ones. But long before steel reaches its melting point, it loses strength. The weaker a steel column gets, the less able it is to carry its assigned or reassigned load. Similarly, fires could make unprotected steel floor supports sag, adding stress and pulling down on the exterior and core columns to which they were attached. Ultimately, if the structural steel in the impact zone became hot enough for long enough, or was forced to carry too much added weight, it would buckle. If that happened,
...more
