Andy Champ wrote:
Brian G wrote:

It's the same with lintels and floor joists. In intense heat, a
metal lintel or joist will bend, warp and collapse quite quickly,
whereas wooden ones will burn on the outside but retain their
strength for quite a long period - and that's one of the reasons you
will often see structural steel surrounded with reinforced concrete.



ISTR one of the problems with the World Trade Center (sic) in 9/11 was
that the impact tore much of the fireproofing off the steel.

Andy

It was Andy - along with I believe, a design problem with the floor girders
to wall stanchions connection that allowed the building to fall like 'a pack
of cards' when a the weight of the top sections dropped onto the other
floors below.

Brian G