The fact that the Reinhardt cremation facilities as described by the witnesses would have been unable to hold up their load during a cremation had been discussed in three previous posts. This time we’ll look at a factor which has been ignored until now: buckling.
What is lateral torsion buckling? It’s when a beam deforms like this:
The beam in this experiment failed through lateral torsion buckling.
In fact, it appears that in a fire unrestrained I-beams always fail through lateral torsion buckling. That is, they buckle before they reach their theoretical yield strength. (This does not normally happen in actual structures because the beams are restrained, which (assuming the engineers who designed the structure didn’t do anything stupid) prevents buckling. One study supporting this statement is mentioned in the 2001 doctoral thesis The Behaviour of Multi-storey Composite Steel Framed Structures in Response to Compartment Fires by Susan Lamont:
An empirical study supporting this is mentioned in the 2007 thesis A Study of the Effects of High Temperature on Structural Steel Framing by Konstantinos Miamis; the data are shown in this figure:
Two things should be noted. First, lateral torsion buckling is more of a factor for slender beams. While I don’t know the non-dimensional slenderness of a length of rail, I think it’s safe to say that rails are not slender (at least in profile; they could be slender with respect to their length).
Second, lateral torsion buckling becomes more of a factor the higher the temperature is. At 600 C, even the least slender of beams buckled at a a little over 60% of their yield strength, while at 300 C they did not buckle at all.
Without direct data on the buckling of rails it’s hard to be sure, but given the very high temperatures that the rails would have reached at the alleged Reinhardt cremation facilities (far greater than 600 C) it seems likely that lateral torsion buckling would have reduced their strength quite significantly.