The construction of high-rise buildings shall comply with
the provisions of Sections 403.2.1 through 403.2.4.
403.2.1
Reduction in fire-resistance
rating. The fire-resistance-rating reductions listed in
Sections 403.2.1.1 and 403.2.1.2 shall be allowed in buildings that have
sprinkler control valves equipped with supervisory initiating devices and
water-flow initiating devices for each floor.
403.2.1.1
Type of construction.
The following reductions in the minimum
fire-resistance rating
of the building elements in Table 601 shall be permitted as follows:
1. For buildings not greater than 420 feet
(128 m) in
building height, the
fire-resistance
rating of the building elements in Type IA construction shall be
permitted to be reduced to the minimum
fire-resistance ratings
for the building elements in Type IB.
Exception: The required fire-resistance
rating of columns supporting floors shall not be permitted to be
reduced.
2. In other than
Group F-1, M and S-1 occupancies, the fire-resistance rating
of the building elements in Type IB construction shall be permitted to be
reduced to the fire-resistance ratings in Type IIA.
3. The building height and
building area limitations of a building containing building
elements with reduced fire-resistance ratings shall be
permitted to be the same as the building without such reductions.
403.2.1.2
Shaft
enclosures. For buildings not greater than 420 feet (128 m) in
building height, the required fire-resistance
rating of the fire barriers enclosing vertical
shafts, other than exit
enclosures and
elevator hoistway enclosures, is permitted to be reduced to 1 hour where
automatic sprinklers are installed within the shafts at the top and at
alternate floor levels.
403.2.2
Seismic considerations.
For seismic considerations, see Chapter 16.
403.2.3
Structural integrity of exit
enclosures and elevator hoistway enclosures. For high-rise buildings of
occupancy category III or IV in accordance with Section 1604.5, and for all
buildings that are more than 420 feet (128 m) in building
height, exit
enclosures and elevator
hoistway enclosures shall comply with Sections 403.2.3.1 through 403.2.3.4.
403.2.3.1
Wall assembly. The
wall assemblies making up the exit
enclosures
and elevator hoistway enclosures shall meet or exceed Soft Body Impact
Classification Level 2 as measured by the test method described in ASTM C
1629/C 1629M.
403.2.3.2
Wall
assembly materials. The face of the wall assemblies making up the
exit
enclosures and elevator hoistway
enclosures that are not exposed to the interior of the
exit
enclosure or elevator hoistway enclosure shall be constructed
in accordance with one of the following methods:
1. The wall assembly shall incorporate not
less than two layers of impact-resistant construction board each of which meets
or exceeds Hard Body Impact Classification Level 2 as measured by the test
method described in ASTM C 1629/C 1629M.
2. The wall assembly shall incorporate not
less than one layer of impact-resistant construction material that meets or
exceeds Hard Body Impact Classification Level 3 as measured by the test method
described in ASTM C 1629/C 1629M.
3. The wall assembly incorporates multiple
layers of any material, tested in tandem, that meet or exceed Hard Body Impact
Classification Level 3 as measured by the test method described in ASTM C
1629/C 1629M.
403.2.3.3
Concrete and masonry walls. Concrete or masonry walls shall be
deemed to satisfy the requirements of Sections 403.2.3.1 and
403.2.3.2.
403.2.3.4
Other
wall assemblies. Any other wall assembly that provides impact resistance
equivalent to that required by Sections 403.2.3.1 and 403.2.3.2 for Hard Body
Impact Classification Level 3, as measured by the test method described in ASTM
C 1629/C 1629M, shall be permitted.
403.2.4
Sprayed fire-resistant
materials (SFRM). The bond strength of the SFRM installed throughout the
building shall be in accordance with Table 403.2.4.
TABLE 403.2.4 MINIMUM BOND STRENGTH
|
HEIGHT OF
BUILDINGa |
SFRM MINIMUM BOND STRENGTH |
| Up to 420 feet |
430 psf |
| Greater than 420 feet |
1,000 psf |
For SI: 1 foot = 304.8 mm, 1 pound per square foot
(psf) = 0.0479 kW/m2.
a. Above the
lowest level of fire department vehicle access. |
