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The method from NBC appendix D 2.11 is an older, empirical method that applies only to glulam beams and columns.
It uses a formula based on loading relative to capacity, section dimensions, and effective length of the member as defined for buckling calculations to determine a fire rating in minutes, and this is compared to the allowable endurance.
You specify the fire endurance, which can be 45 min, 1 hr, 1.5 hrs or 2 hrs.
You can also specify materials covering the exposed member that protect it from burning and increase the fire endurance. ½” gypsum board increases endurance by 15 minutes, 5/8” gypsum board by 30 minutes, and two ply 5/8 by 1 hr.