MIL-HDBK-1191
NOTE 3: Number of Stories. The walk-on platforms constituting the floor level
of the distribution zones do not constitute separate stories. Each occupied
zone and its corresponding floor is counted as an independent floor level.
13.14.2
Construction.
13.14.2.1
Floor-to-Floor Fire Separation. A 2 hour fire resistive
separation is required between floors. The fire resistance rating runs in a
horizontal plane along the utility pod floor, then vertically along the wall
separating the utility pod from the occupied zone and connection zone. The
fire resistance rating then continues along the walk-on platform to the
outside wall. The walk-on platform of the distribution zone shall be designed
in accordance with NBSIR 85-3158 (reference 13m). See Figure 13-1.
13.14.2.2
Occupied Zone.
a) The building modules of IBS facilities at the occupied zone shall be
the designated smoke compartments separated from each other by 1 hour fire
rated construction. These separations shall meet the smoke barrier
requirements of NFPA 101 (reference 13a).
b) Walls, smoke barrier partitions, occupancy separations (not greater
than 2 hour fire resistance) and horizontal exit walls shall terminate at the
bottom of the walk-on platform. Occupancy separations (2 hour fire resistance
and greater) of multi-story facilities shall not terminate at the walk-on
platform, but pass continuously through the distribution zone and structural
floor and terminate at the bottom of the occupied zone floor above.
13.14.2.3
Distribution Zone.
a) Dividing the distribution zone into smoke compartments with smoke
barriers is not required.
b) Horizontal exit or smoke barrier walls, located in the
occupied/connection zone need not be extended up into the Distribution Zone.
13.14.2.4
Utility Pods.
a) Utility Pods shall be separated from the distribution zones by 1
hour fire rated construction and from the occupied and connection zones by 2
hour fire resistive construction.
b) The structural members in the utility pod shall have a 2 hour fire
resistive rating.
13.14.2.5
Structural Members.
a) Columns. All columns shall be provided with the required degrees of
fire resistance within all zones.
b) Occupied Zone Floor. As part of the IBS floor/ceiling assembly, the
occupied zone floor slab, except at the utility pod, is not required to have
an independent fire resistance rating. However, all penetrations shall be
firestopped.
c) Other Structural Members. Primary structural members (supporting
more than one floor) located within the distribution zone, such as columns and
girders and trusses, shall have a 2-hour fire resistive rating or be protected
in accordance with the fire resistance requirements of the Uniform Building
13-8
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