As an alternative to Section 1607.9.1, floor 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.
- A reduction shall not be permitted in Group A occupancies.
- 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 20 percent.
Exception: 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.
- 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.
- 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 16-27.
- For one-way slabs, the area, A, for use in Equation 16-27 shall not exceed the product of the slab span and a width normal to the span of 0.5 times the slab span.
For SI: R = 0.861(A — 13.94)
Such reduction shall not exceed the smallest of:
- 40 percent for horizontal members
- 60 percent for vertical members; or
- R as determined by the following equation:
A = Area of floor or roof 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.