Diaphragm question 1

[dgengineering]

I have a small irregular shape building and need to design the shear walls. Can the highlighted shear line be one line or should I treat these two areas (1 and 2) as different diaphragms.
In my opinion it can be one line with two different tributary areas (one diaphragm). Please see attached.

Now my coworker is saying that they should be 2 different diaphragms since area 2 is vaulted. What do you think?

Thank you so much in advance.

 

[JAE]

Maybe a better sketch? Having difficulty understanding the geometry of the roof.

 

[BAretired]

Indeed! That is one terrible sketch.

 

[AaronMcD]

Tension is only transferred through collector lines anyway. I'd have a continuous collector from 2.1 to 7. Make sure to account for the vertical component at the intersection of the 2 roofs. One shear line. Depending on shear walls and load from each roof, the collector load at the intersection may be very small.

The roofs are gonna try and pull apart/push together whatever you do, so just make sure there's enough collector lines to keep em from separating. I'd also put a collector along line 8 at the re-entrant corner.

http://www.hellodwell.design

 

[KootK]

Now my coworker is saying that they should be 2 different diaphragms since area 2 is vaulted.

1) In the context of North American work, I would say that the vault is irrelevant. That, because we generally do not use ceiling diaphragms in North America. We get it all done with the roof sheathing.

2) Is there a vertical step in the roof sheathing at [5]? I would expect so and, if that's the case, that would likely steer me towards treating the two areas a separate diaphragms. The detailing required to enforce flexural diaphragm continuity across a vertical sheathing step is usually pretty onerous.

 

[Harbringer]

I won't even try and answer. I'm putting more effort into this response than you did in that sketch.