Section 27-563. Partial loading conditions

(a) Uniformly distributed loads.
  In continuous framing and  cantilever  construction,  the  design  shall
  consider  live  load  on all spans and arrangements of partial live load
  that will produce  maximum  stresses  in  the  supporting  members.  The
  simplifications   given   in   paragraphs  one  through  three  of  this
  subdivision are permissible.
    (1) FLOOR AND ROOF FRAMING.
    a. For vertical live load applied to the  level  under  consideration,
  the far ends of the columns above and below that level may be assured as
  fixed.
    b. Combinations of live load may be limited to the following:
    1. Live load placed on two adjacent spans.
    2.  Live  load  placed on alternate spans. The effects of live load on
  spans more than two spans away from the span under consideration may  be
  neglected.
    (2) ARCHES AND GABLED FRAMES.
    a. Live load placed on 1/2 span adjacent to one support.
    b. Live load placed on the center 1/4 span.
    c. Live load placed on 3/8 the span adjacent to each support.
    (3)  COLUMNS. Moments due to vertical loads may be calculated from the
  live load on the  largest  single  adjacent  span  of  the  floor  under
  consideration.  This  moment  shall  be assumed to act concurrently with
  live load on all other floors.
    (b) Moving concentrated loads. Structural  members  supporting  moving
  concentrated  loads  shall  be  designed  for  only those loads that can
  physically occur simultaneously and  are  arranged  to  produce  maximum
  stresses.