The minimum equivalent thicknesses of cast-in-place or precast concrete walls for fire-resistance ratings of 1 hour to 4 hours are shown in Table 7126.96.36.199. For solid walls with flat vertical surfaces, the equivalent thickness is the same as the actual thickness. The values in Table 7188.8.131.52 apply to plain, reinforced or prestressed concrete walls.
|MINIMUM SLAB THICKNESS (inches) |
FOR FIRE-RESISTANCE RATING OF
|1 hour||11/2 hours||2 hours||3 hours||4 hours|
|For SI: 1 inch = 25.4 mm.|
The thickness of panels with tapered cross sections shall be that determined at a distance 2t or 6 inches (152 mm), whichever is less, from the point of minimum thickness, where t is the minimum thickness.
The equivalent thickness of panels with ribbed or undulating surfaces shall be determined by one of the following expressions:
|s||=||Spacing of ribs or undulations.|
|te||=||Equivalent thickness of the panel calculated as the net cross-sectional area of the panel divided by the width, in which the maximum thickness used in the calculation shall not exceed 2t.|