Subject to the limitations of Sections 1607.10.1.1 through 1607.10.1.3 and Table 1607.1, members for which a value of K LLAT is 400 square feet (37.16 m2) or more are permitted to be designed for a reduced uniformly distributed live load, L, in accordance with the following equation:
|L||=||Reduced design live load per square foot (m2) of area supported by the member.|
|Lo||=||Unreduced design live load per square foot (m2) of area supported by the member (see Table 1607.1).|
|KLL||=||Live load element factor (see Table 1607.10.1).|
|AT||=||Tributary area, in square feet (m2).|
|Interior columns |
Exterior columns without cantilever slabs
|Edge columns with cantilever slabs||3|
|Corner columns with cantilever slabs |
Edge beams without cantilever slabs
|All other members not identified above including: |
Edge beams with cantilever slabs
Members without provisions for continuous shear
transfer normal to their span
Live loads that exceed 100 psf (4.79 kN/m2) shall not be reduced.
- The live loads for members supporting two or more floors are permitted to be reduced by a maximum of 20 percent, but the live load shall not be less than L as calculated in Section 1607.10.1.
- For uses other than storage, where approved, additional live load reductions shall be permitted where shown by the registered design professional that a rational approach has been used and that such reductions are warranted.
As an alternative to Section 1607.10.1 and subject to the limitations of Table 1607.1, uniformly distributed live loads are permitted to be reduced in accordance with the following provisions. Such reductions shall apply to slab systems, beams, girders, columns, piers, walls and foundations.
1. A reduction shall not be permitted where the live load exceeds 100 psf (4.79 kN/m2) except that the design live load for members supporting two or more floors is permitted to be reduced by a maximum of 20 percent.
2. A reduction shall not be permitted in passenger vehicle parking garages except that the live loads for members supporting two or more floors are permitted to be reduced by a maximum of 20 percent.
3. For live loads not exceeding 100 psf (4.79 kN/m2), the design live load for any structural member supporting 150 square feet (13.94 m2) or more is permitted to be reduced in accordance with Equation 16-24.
4. For one-way slabs, the area, A, for use in Equation 16-24 shall not exceed the product of the slab span and a width normal to the span of 0.5 times the slab span.
|R = 0.08(A – 150)||(Equation 16-24)|
1. 40 percent for horizontal members;
2. 60 percent for vertical members; or
3. R as determined by the following equation.
|R = 23.1(1+ D/Lo)||(Equation 16-25)|
|A||=||Area of floor supported by the member, square feet (m2).|
|D||=||Dead load per square foot (m2) of area supported.|
|Lo||=||Unreduced live load per square foot (m2) of area supported.|
|R||=||Reduction in percent.|