Stress reduction at wood stud walls (fire-rated)
Stress reduction at wood stud walls (fire-rated)
(OP)
In the UBC and IBC, there is an "obscure" footnote in the fire-rated wall assembly tables. It simply requires a reduction of allowable fc' stress (multiply by 0.78) for design of load-bearing stud walls if wall is fire-rated. (I don't have access to the Codes now, so I can't give a page or section reference).
My question- does the reduction also apply to the bearing stud (post) at each end of header/beam? If so, what about double or triple studs at ends of headers? Are those considered more fire-resistant being nailed together as a multi-ply "post"? Finally, what about any 4x or 6x post in the wall?
My question- does the reduction also apply to the bearing stud (post) at each end of header/beam? If so, what about double or triple studs at ends of headers? Are those considered more fire-resistant being nailed together as a multi-ply "post"? Finally, what about any 4x or 6x post in the wall?






RE: Stress reduction at wood stud walls (fire-rated)
RE: Stress reduction at wood stud walls (fire-rated)
UBC 1997 (Vol. 1) Table 7-B, Footnote 18 (page 1-84)
IBC 2000 Table 719.1(2), Footnote (m) (page 130)
IBC 2003 Table 720.1(2), Footnote (m) (page 121)
RE: Stress reduction at wood stud walls (fire-rated)
But the footnote m refers to "studs" which I would take, technically speaking, to be the repetitive structural wood components in the wall...which would include the bearing stud and mulitiple studs on either side of openings.
But I would think that a built-up column within the wall, supporting a separate beam, would be looked at as a column, not a part of a stud wall.
RE: Stress reduction at wood stud walls (fire-rated)
Amazing how things in the Code go unnoticed for years until a sharp-eyed plans checker catches something.