industrial buildings. The general layout of a bracing system and the sizing of members must be determined
for each case in order to meet the requirements for load resistance and deformation control. The bracing
system will be fully developed in both directions so that the bracing diagonals and chord members form
complete horizontal trusses between vertical-resisting elements (Figure 7-47). Horizontal bracing systems
will be designed using diaphragm design principles.
(1) Diaphragm classification. Floor diaphragms shall be classified as either flexible, stiff, or rigid,
as indicated in Figure 7-45.
Diaphragms shall be considered flexible when the maximum lateral
deformation of the diaphragm along its length is more than twice the average interstory drift of the story
immediately below the diaphragm. For diaphragms supported by basement walls, the average interstory
drift of the story above the diaphragm may be used in lieu of the basement story.