Diaphragm Chord Force Transfer
Diaphragm Chord Force Transfer
(OP)
I’ve got a 520’ x 270’ warehouse with CMU shear walls only on the sides (spaced 520’ apart). All roof framing members span front to back (with intermediate beams). The back of the building is continuous CMU but the front of the building is mostly storefront and has several offsets (as large as three feet). Consider wind blowing at the back of the building, what is the customary way to transfer diaphragm chord forces across the front of the building at the offsets? Do I ignore this? Do I add diagonals at the offsets? Do a add members parallel to the back wall that "span across" the offsets?






RE: Diaphragm Chord Force Transfer
Regards,
Jim Emanuel, S.E.
RE: Diaphragm Chord Force Transfer
Regarding the offsets, if the outer most member is discontinuous (at offsets) then use the 1st continuous member across all offsets as the chord. The members outboard of the chord will just go along for the ride.
RE: Diaphragm Chord Force Transfer
I set a row of columns just inside the offsets, and ran joists between the columns. The joists were set on a cap plate to the column so that their ends were only seperated by a small gap, then anlges ( with vertical leg turned down)were welded accross the gap to the top chords of adjacent joist shoes. This made a continous chord.
I used a joist loading diagraphm to give the joist supplier the necessary chord forces he needed to design the joists for.
RE: Diaphragm Chord Force Transfer
RE: Diaphragm Chord Force Transfer
DaveAtkins