Back-to-Back Shearwalls 3

[SHEAR_FORCE]

Hello!

I have a client who offered an unconventional concept for using two double-sided shearwalls back-to-back to form a high load shearwall (2 studwalls, 4 sheets of ply total). We are considering this for a an exterior wall application on the lower level of a three-story home, in lieu of a frame system at the garage. Obviously, the holdown anchorage would need to be custom and the constructability of said wall would be difficult. Is there anything in the code that would prohibit this? Are there other complications that would make this impossible?

tia

 

[SHEAR_FORCE]

I just found this back-to-back WSWH option from Simpson: Link

I know this is a tested system but it certainly seems more feasible knowing that they allow it.

 

[JoshPlumSE]

I don't think there is anything against it. From a practical standpoint you might have anchorage issues..... meaning overlapping pullout cones for your headed anchors. Which will tend to make your anchorage less efficient.

In a case like this I might use a structural plate connecting the two anchors together at the headed bolt. We did this occasionally for the anchorage of tall vertical vessels in industrial construction. Though you have to be careful that air pockets don't develop in the foundation below the plate.

 

[phamENG]

Seems it could work. Constructability isn't really an issue - it's inspectability.

Build the wall segments on the ground with one side sheathed. Inspect the sheathing and nailing.
Stand up the walls and anchor them (periodic shear anchorage and chord hold downs). Inspect the anchorage and hold downs.
Fasten outer WSP sheathing to both sides of assembly and fasten.
Your collector will need to be the full width of your assembly, I think, to transfer the loads properly. Though you may be able to accomplish it with a fancy blocking arrangement.
Inspect the remainder of the nailing and connections.

No AHJ is going to do 3 separate inspections for the a single shear wall. By the time they pay for the added detailing and your added inspection time, that double Simpson deal is probably cheaper.