Chord Force Blocking Detail
Chord Force Blocking Detail
(OP)
I have a long and skinny billets building with cmu walls and wood trusses spaced at 2 ft o.c. Please see the attached drawing and details. There is a 3500 pound chord force that I would like to transfer into the bond beam at the top of the cmu shear wall. There is about a 4'-0" elevation difference between the top of the roof sheathing and the top of the shear wall. I have detailed truss blocking panels running between the main roof trusses to transfer the chord force into the shear wall. The question I have is; does each blocking panel and the connections to and from the blocking panels have to be designed to take the 3500 pound force or do all of the blocking panels share in transferring the 3500 pound chord force into the shear wall?
I appreciate any help or guidance you can give me. Please feel free to comment on anything I have detailed too. Thanks!
I appreciate any help or guidance you can give me. Please feel free to comment on anything I have detailed too. Thanks!






RE: Chord Force Blocking Detail
RE: Chord Force Blocking Detail
DaveAtkins
RE: Chord Force Blocking Detail
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Chord Force Blocking Detail
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Chord Force Blocking Detail
1) Might be cheaper/easier to run the block all the way up and just hang the trusses from the sides of the CMU.
2) We discussed something similar here: Link
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Chord Force Blocking Detail
RE: Chord Force Blocking Detail
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Chord Force Blocking Detail
RE: Chord Force Blocking Detail
I thought that the chord forces behave like the chords in a simple supported truss - Maximum where the moment is maximum
I.E. for a simple truss the max chord force is wl^2/8 / d at midspan, and likewise for the diaphragm chord force?
Unless we're talking about collectors/drags of course...
RE: Chord Force Blocking Detail
That is true of the aggregate chord axial force (kN rather than kN/m) but not the shear being transferred to the chord (kN/m). Continuing with your truss analogy, the forces in your truss webs (max at ends) are analogous to the shear force being transferred to the chords (also max at ends). The forces on the shear panels being considered here are governed by the shear being transferred to the chord (bond beam).
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Chord Force Blocking Detail
RE: Chord Force Blocking Detail
At the risk of sounding obtuse, what braces? Are you envisioning intermittent diagonal bracing in the vertical plane connecting the strapping and blocking to the top of the block wall? I've no doubt that your approach is sound. I just want to understand the details being proposed.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.