Page 398 - 2018_Complete_14_Collection (1)_Neat

STRUCTURAL DESIGN

1607.11 Reduction in uniform live loads. Except for uni- not greater than 20 percent, but the live load be shall
form live loads at roofs, all other minimum uniformly distrib- be not less than L as calculated in Section 1607.11.1.

uted live loads, L , in Table 1607.1 are permitted to be TABLE 1607.11.1
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reduced in accordance with Section 1607.11.1 or 1607.11.2. LIVE LOAD ELEMENT FACTOR, K LL
Uniform live loads at roofs are permitted to be reduced in ELEMENT K LL
accordance with Section 1607.13.2. Interior columns 4
1607.11.1 Basic uniform live load reduction. Subject to Exterior columns without cantilever slabs 4
the limitations of Sections 1607.11.1.1 through Edge columns with cantilever slabs 3
1607.11.1.3 and Table 1607.1, members for which a value
2
of K A is 400 square feet (37.16 m ) or more are permit- Corner columns with cantilever slabs 2
Edge beams without cantilever slabs
2
LL
T
ted to be designed for a reduced uniformly distributed live Interior beams 2
load, L, in accordance with the following equation:
Members not previously identified including:
15

L = L 0.25 + -------------------- T   (Equation 16-23) Edge beams with cantilever slabs 1

o
Cantilever beams
K A
LL
One-way slabs
4.57

For SI: L = L 0.25 + --------------------   Two-way slabs
Members without provisions for continuous shear

o
K A
transfer normal to their span
where: LL T 1607.11.2 Alternative uniform live load reduction. As an
2
L= Reduced design live load per square foot (m ) of alternative to Section 1607.11.1 and subject to the limita-
area supported by the member. tions of Table 1607.1, uniformly distributed live loads are
2
L = Unreduced design live load per square foot (m ) of permitted to be reduced in accordance with the following
o
area supported by the member (see Table 1607.1). provisions. Such reductions shall apply to slab systems,
K = Live load element factor (see Table 1607.11.1). beams, girders, columns, piers, walls and foundations.
LL
2
A = Tributary area, in square feet (m ). 1. A reduction shall not be permitted where the live
2
T
load exceeds 100 psf (4.79 kN/m ) except that the
L shall be not less than 0.50L for members supporting design live load for members supporting two or
o
one floor and L shall be not less than 0.40L for members more floors is permitted to be reduced by not greater
o
supporting two or more floors. than 20 percent.
1607.11.1.1 One-way slabs. The tributary area, A , for Exception: For uses other than storage, where
T
use in Equation 16-23 for one-way slabs shall not approved, additional live load reductions shall be
exceed an area defined by the slab span times a width
normal to the span of 1.5 times the slab span. permitted where shown by the registered design
professional that a rational approach has been
1607.11.1.2 Heavy live loads. Live loads that exceed used and that such reductions are warranted.
2
100 psf (4.79 kN/m ) shall not be reduced. 2. A reduction shall not be permitted in passenger
Exceptions: vehicle parking garages except that the live loads for
1. The live loads for members supporting two or members supporting two or more floors are permit-
more floors are permitted to be reduced by not ted to be reduced by not greater than 20 percent.
greater than 20 percent, but the live load shall 3. For live loads not exceeding 100 psf (4.79 kN/m ),
2
be not less than L as calculated in Section the design live load for any structural member sup-
1607.11.1. porting 150 square feet (13.94 m ) or more is permit-
2
2. For uses other than storage, where approved, ted to be reduced in accordance with Equation 16-24.
additional live load reductions shall be permit- 4. For one-way slabs, the area, A, for use in Equation
ted where shown by the registered design pro- 16-24 shall not exceed the product of the slab span
fessional that a rational approach has been and a width normal to the span of 0.5 times the slab
used and that such reductions are warranted. span.
1607.11.1.3 Passenger vehicle garages. The live loads R = 0.08(A – 150) (Equation 16-24)

shall not be reduced in passenger vehicle garages. For SI: R = 0.861(A – 13.94)

Exception: The live loads for members supporting Such reduction shall not exceed the smallest of:
two or more floors are permitted to be reduced by
1. 40 percent for members supporting one floor.
2018 INTERNATIONAL BUILDING CODE ® 371
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