// CODE SNIPPET
721.5.1.3 Spray-Applied Fire-Resistant Materials
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The fire resistance of wide-flange structural steel columns protected with spray-applied fire-resistant materials, as illustrated in Figure 721.5.1(5), shall be permitted to be determined from the following expression:
where:
Exception: The fire resistance of structural steel columns protected with intumescent or mastic fire-resistant coatings shall be determined on the basis of fire-resistance tests in accordance with Section 703.2.
where:
| R | = | Fire resistance (minutes). |
| h | = | Thickness of spray-applied fire-resistant material (inches). |
| D | = | Heated perimeter of the structural steel column (inches). |
| C1 and C2 | = | Material-dependent constants. |
| W | = | Weight of structural steel column (pounds per linear foot). |
Exception: The fire resistance of structural steel columns protected with intumescent or mastic fire-resistant coatings shall be determined on the basis of fire-resistance tests in accordance with Section 703.2.
The material-dependent constants, C1 and C2, shall be determined for specific fire-resistant materials on the basis of standard fire endurance tests in accordance with Section 703.2. Unless evidence is submitted to the commissioner substantiating a broader application, this expression shall be limited to determining the fire resistance of structural steel columns with weight-to-heated-perimeter ratios (W/D) between the largest and smallest columns for which standard fire-endurance test results are available.
Spray-applied fire-resistant materials shall be identified by density and thickness required for a given fire-resistance rating.