Wood shear walls supported on piers

[milkshakelake]

I think I know how to do this but I need a quick sanity check.

I have 2 wood stories supported on concrete piers, while the rest of the building is supported on typical spread footings, due to sloped grade. For the area supported on piers, my initial thought is that I'd need concrete or steel beams to support the overhang. Is that correct? The reason I'm thinking this way is that I don't think I'll be able to get a massive timber or LVL beam there to work, and the discontinuity in vertical stiffness means that the beams have to be designed for seismic overstrength.

 

[driftLimiter]

If you have hold down forces on the span of the beam from seismic loads then overstrength seems reasonable. Seems like a big enough VSL could take it but idk your loading.

I wouldn't try a concrete beam here if it truly needs to be elevated the steel beam is simpler to install imo.

The shear load on the piers has me interested. Have you thought about where that load wants to go?

 

[driftLimiter]

I was picturing a steel beam over concrete columns(piers). You could do a grade beam to get better fixity at the bottom and give more mass for overturning and sliding.
That system would work all the better if you can have a concrete beam at the top of the piers.

 

[milkshakelake]

The piers are used to reduce some of the excavation requirement (the zoning doesn't allow for more than a certain amount to be excavated), so I wouldn't be able to put grade beams there. Anyway, I think similar fixity can be made at the top rather than the bottom like in the second comment.

The issue I see with steel beams is figuring out where the lateral shear goes, as you pointed out in a way. It would only work if I assume that the foundations have some fixity, which is hard to justify without grade beams. With this reasoning, I think concrete moment frame makes more sense.

I suppose some kind of engineered wood beam could work, but I'd run into the problem of where to dump the lateral shear once it goes into the piers.