OMF in otherwise wood shear wall system

[rn14]

Variations of this discussion have occurred here before. My particular case falls within exceptions where I can use R=6.5 for shear walls and R=3.5 for the OMF (rather than 3.5 for everything). That makes me happy. I wanted to be sure I am reading exception 3 of 12.2.3.3 of ASCE 7-10 correct. If I proceed with this method do my diaphragms need to be designed for R=3.5 forces? I'm quite sure it does but speaking with other engineers I don't know any that actually do.

 

[Deker]

Yes, if your diaphragm can be classified as flexible then you can design each line of resistance using its respective value of R. Diaphragm design uses the least value of R in that direction (3.5 for your case).

 

[DETstru]

Assuming your OMF and shear walls are two different lines of resistance, yes.
I'm also assuming you have a flexible diaphragm, 2 stories or less, and are Risk Category I or II.

You design the OMF with R=3.5
The shear wall with R=6.5
And the diaphragm with R=3.5