People don’t often realize this but wood timber construction can be safer in a fire than steel beam construction because wood chars on the outside, turning to carbon in the extreme, but that layer of char protects the interior and leaves appreciable amounts of a beam’s strength intact till well after a nominally comparable strength, or even much stronger, steel beam would soften and fail in the same fire.
You don’t have to heat up steel that much to seriously weaken it.
Please note: wood “timber” ... not white pine 2x4s that are only 1.5” x 3.5” in actual dimension like too many houses are built of today. Timber implies something more substantial than mere sticks of sometimes cheap wood ... so don’t imagine that I’m saying anything in praise of the latter. Thanks.
***but that layer of char protects the interior and leaves appreciable amounts of a beam’s strength intact till well after a nominally comparable strength,***
I have charred beams in my barn that were salvaged from a burned railroad bridge near here about 100 years ago.
They retained their strength enough to be used in barn construction.
People don’t often realize this but wood timber construction can be safer in a fire than steel beam construction because wood chars on the outside, turning to carbon in the extreme, but that layer of char protects the interior and leaves appreciable amounts of a beam’s strength intact till well after a nominally comparable strength, or even much stronger, steel beam would soften and fail in the same fire.
You don’t have to heat up steel that much to seriously weaken it.
Please note: wood “timber†... not white pine 2x4s that are only 1.5†x 3.5†in actual dimension like too many houses are built of today. Timber implies something more substantial than mere sticks of sometimes cheap wood ... so don’t imagine that I’m saying anything in praise of the latter. Thanks.
Good point! I recall in a class once seeing a picture of a building that had burned. There was a charred, but intact, glue-lam beam over which a melted steel I-beam had draped itself.