In a free-standing garage, where one wall is almost entirely absent to
make a door opening, what parts of the structure prevent the door wall
from racking?
I am second-guessing myself about my shed plan. One wall, a gable end
wall, is non-load-bearing but is a shear wall. Its plan has an 8x8
door opening in a 12' wide by 9' high wall. I don't have the
background to determine whether such a wall will have sufficient shear
strength. I'm using conventional 2x4 framing 16" OC with APA-rated
7/16 OSB sheathing, no interior sheathing is planned.
The obvious things would be to reduce the door opening, to use heavier
sheathing, and/or sheathe it inside and out. But first I would like
to hear any advice this august group has to offer, and with my thanks.

An 8' door in a 12' wall doesn't leave much to resist shear forces from
winds or earthquakes. It would be best to increase the shed to 16' wide, or
reduce the door to 6' wide so you can have at least 32" on each side (more
would be better).

I'm no engineer, but another option might be to shift the door to one side
so you can increase the width of a shear wall section.

Otherwise, the only solution I can think of would be a welded steel "moment
frame" that basically makes the entire 12' wall a stiff frame than can't
rack. But that could be an expensive option and would probably need
engineer approval with the building department.

Regardless, you'll need to tie the shear walls securely to the foundation
with special anchor ties (Simpson SSTB) and hold downs (Simpson PHD).

Anthony