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Discontinuous Diaphragm Connection

Discontinuous Diaphragm Connection

Discontinuous Diaphragm Connection

(OP)
I am working on a multi-level complex wood apartment building. One that is all cut up on the exterior walls with lots of horizontal irregularities. However, for the most part all of the diaphragms are similar. I have attached a diagram of the one I am analyzing. Which is repeated 20+ times, so I would like to have a good idea of what is required and what is economical.

My question is related to the discontinuous diaphragm chord member in the attached drawing. The way it stands now, there will be a header recessed up into the floor truss system or there will be a girder truss that will be the same depth. However, no header is allowed below the bottom of the floor truss system. As seen in the attachment, there is 1060# of tension due to chord bending to transfer into the header/girder. My initial thought is to strap on top of the framed wall and then to the underside of the header/girder. It seems like a hinge would for at that connection though as the strap would be relatively weak in "bending" across its width. I am trying to avoid using the little 6' perpendicular wall to resist the large diaphragm shear forces.

Maybe there is a better way to accomplish this transfer of force.

RE: Discontinuous Diaphragm Connection

Use a beam on Section B-B and tie it to the rim joist of Section A-A using metal plates on each side. That way, the diaphragm chord can be continuous from end to end.

BA

RE: Discontinuous Diaphragm Connection

This is common in multi-level wood buildings and is easy to deal with. You can either put a beam in as BA mentioned and use straps to tie them together for tension forces or you can use blocking and straps between trusses/joists or you can use a transfer diaphragm and have a discontinuous chord. The easiest is to add something to act as the chord and lap it with a strap. The strap only takes tension and the compression force is transferred through bearing (compression perpendicular to grain can control for these conditions). You may want to check out Terry Malone's book "The Analysis of Irregular Shaped Diaphragms" available through the ICC. It covers situations like this pretty well. That's actually not too bad of a layout. I've had much, much worse recently.

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