http://www.softwood.org/cms/data/img/uploads/files/AITC_Superior_Fire_UK.pdf (see pages 3 & 4)
When exposed to fire wood retains its strength for a
longer period of time than metal. Unprotected metals
quickly lose their strength and collapse suddenly,
often with little warning. In contrast, wood loses
strength slowly and only as material is lost through
surface charring.
Average building fire temperatures range from
approximately 700º to 900º Celsius. Steel weakens
dramatically as its temperature climbs above 230ºC,
retaining only 10% of its strength at about 750ºC.
As a rule, wood will not ignite until it reaches a temperature
of around 250ºC. Once it catches fire, wood typically
develops char at the rate of 0.64mm per minute
under severe fire conditions. The char naturally insulates
the wood and raises the temperature level it can
withstand. Thus, in a 30-minute fire, only 19mm of
each exposed surface of the glulam is lost to charring,
leaving most of the original cross section intact.
http://facweb.northseattle.edu/ssimmons/Winter/2012/TDR%20134/PPTs/Chapter4.ppt.pptx (see slide 4)
“Large wood members have greater resistance to fire than unprotected steel.
Steel, due to its high thermal conductivity, quickly heats up and loses strength during fires.
Large timbers are slow to absorb heat, slow to catch fire, and slow to burn.
The charred outer layer of a partially-burned timber insulates and protects the inner undamaged portion of the timber which retains the capacity to carry some load.”
Interesting. Often things are not as they appear at first blush. Engineered wood is very strong (and completely repeatable...each beam is just as strong as the one next to it) and it can be made as thick as desired. It can also be treated with poisons to make it taste crappy for termites. For those that have an attached garage, go take a look at your door from the house. If it’s to current code, there’s a good chance it’s wood, as wood is also an excellent fireblock.
Having said all that, wood should still be left to compete in the free market...it already has a place in fairly large structures and it should have to show its worth. The idea that we can save the world by building with wood, rather than steel, is just stupid - if for no other reason than that we’ve already (stupidly) built just about every structure we need for the next 20 years anyway, thanks to the housing and related bubbles.
You’re neglecting the presence of concret structural support. Concrete and steel was marketed as being almost fireproof in comparison to wood frame commercial buildings, and by comparison it was.