[Swordmaker]

key point on page 2: Proof stress and tensile strength at 600°C are 0.3-0.4 times those at room temperature.

ThanQ.

Add in that after finishing the 37th floor (IIRC) of building one, the Port Authority in a cost cutting measure, and because the management could not conceive of the need for its protection, discontinued the application of thesprayed-on fire insulation coating on the steel and concrete on all further construction. This coating was intended by the architect and engineers to prevent for a time the heating of the steel until a fire could be extinguished. Without it, no prevention was present.

[buffaloguy]

I looked up the temp versus strength tables and was shocked at how rapidly steel loses its strength with the application of heat. About 1100 fahrenheit at 600 C. Mode than enough to bring it dowm