Different Shearwall configurations Floor-to-Floor

[ash060]

I am checking a 2-story concrete joist building with a few unreinforced masonry shearwalls. There are very few shearwalls from the second floor to the roof, and a bunch that go from the foundation to the 2nd floor.

My question is can you do a rigid diaphragm analysis of the roof find the C.R. and the applied shear and moment. Add that to the 2nd floor diaphragm load and than do a rigid analysis of the 2nd floor? Use those results to design the foundation to 2nd floor shearwalls?

 

[RARWOOD]

What you do is apply the shear at the base of the second story shear walls to the second floor diaphragm. You apply the shear as a concentrated load to the daiphragm. At the same time you have to carry the shear wall chord forces down to the foundation. This may require putting columns under the shear wall chords or building a transfer girder tho resist the vertical forces that act on the shear wall.