Tension Chord in Three-Sided Diaphragm
Tension Chord in Three-Sided Diaphragm
(OP)
I am workng on an addition that has three walls being added to an existing structure. Do the layout of the roof framing plan I am not able to tie in the addition to the existing structure. I looked at the building as a three-sided diaphragm via a Vulcraft publication that I have. My question is, can I use a bar joist to develop the diaphragm tension/compression load for the open end? I have put a call into Vulcraft but I have not heard back yet. I am exploring this as an option.






RE: Tension Chord in Three-Sided Diaphragm
The answer to your question is yes. If the chord force is significant, you should put a note on the drawings instructing the joist supplier to design for the force. But I have found the chord force due to D + 0.75L + 0.75W (or 0.75*0.7E) is usually less than the chord force due to D + L.
DaveAtkins
RE: Tension Chord in Three-Sided Diaphragm
RE: Tension Chord in Three-Sided Diaphragm
In the first paragraph of my response, I was referring to the diaphragm chord.
In the second paragraph of my response, I was referring to the top chord of the joist which is acting as the diaphragm chord.
DaveAtkins
RE: Tension Chord in Three-Sided Diaphragm
Would also think that the D only due to gravity should be checked with the two lateral load conditions.
RE: Tension Chord in Three-Sided Diaphragm
DaveAtkins