Does anyone have any design guidelines that includes fire-resistance performance? I'm currently using a 2002 Onesteel (Australian steel manufacturer) paper, but it's not very useful for any columns taller then 2m.
I have always run with the assumption that grout filling a steel tube increases the fire resistance period (FRP) but have never found concrete evidence of what FRP it is increased by.
The National Building Code of Canada and the Canadian Design of Steel Construction Standard (Limit states design of Steel Structures CAN/CSA S16-01) both have instructions and formulas for that topic.