The grill it treated with ceramics usually, that prevent it from melting.
Secondly, your experiment with the kerosene is flawed, as it doesn't have all the other objects available to give it additional heat. Ie: Chairs, tables, paper, etc. etc. etc.
I can give you the links of quite a few steel framed structures that collapsed from fire alone.
Would you like them?
Here you go.
http://www.fpemag.com/archives/article.asp?issue_id=27&i=153
Here is the USF AAR from the Sight and Sound Theature.
http://www.interfire.org/res_file/pdf/Tr-097.pdf
Here is a near paper on the Perfomance of lightweight steel trusses in fires.
http://fire-research.group.shef.ac.uk/Downloads/SC_Baltimore.pdf
How about the Kader Toy Factory
http://www.wsws.org/articles/2003/may2003/kade-m16.shtml
How about the fire at the Meridian Plaza?
http://www.iklimnet.com/hotelfires/meridienplaza_lessons.html
The concrete structure did NOT collapse, but yet, the steel portion did.
How about that? 3 different fires, 3 collapses of steel framed structures....
ETA: Did you just compare the 1975 fire to the 2001 attack? Holy crap.
Not over 5 floors instantly.
No impact damage
Did not cover the entire floor area.
Holy **** that was stupid....