7184.108.40.206 Gypsum Wallboard Protection
The fire resistance of structural steel columns with weight-to-heated-perimeter ratios (W/D) less than or equal to 3.65 and that are protected with Type X gypsum wallboard shall be permitted to be determined from the following expression:
R = Fire resistance (minutes).
h = Total thickness of gypsum wallboard (inches).
D = Heated perimeter of the structural steel column (inches).
W' = Total weight of the structural steel column and gypsum wallboard protection (pounds per linear foot).
W' = W + 50hD/144.