Wood building elevated on concrete piers

[Croceng78]

Hi, I am designing a wood building that is elevated on concrete piers. The piers are about 4'-6" above the footings. For context, see attached image. For the lateral design, I am using shear walls which have an R value of 6.5. My question is: would I need to consider the concrete piers as cantilever columns with a lower R value (and design the shear walls for that lower R value as well) or just get the reactions from the shear walls above and apply them to the concrete piers and design them that way? Any bit of information helps. Thanks in advance for your time.

 

[dik]

Lateral load from wind? or seismic? You have to isolate the wood and the concrete... else dryrot issues...

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So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JAE]

For seismic you have to design for the lowest R, or do a two-step procedure (see the IBC or ASCE 7 for this if you are in the US).

 

[phamENG]

Yes, that looks like a cantilevered column condition to me. And you would use the lowest R value as JAE says. I don't think a 2-step procedure will work here, since the bottom has to be...what? 10x stiffer than the upper portion?...and I'm pretty sure that won't be the case for this layout.

 

[Croceng78]

Are there any special design considerations for the connection from the wood beam to the concrete cantilever column? I was thinking about using a Simpson CCQM column cap embedded into the concrete pier since it has lateral and uplift capacity.

 

[phamENG]

That is what those are designed for. As long as the connection can take the loads - I believe that connection will be subject to overstrength for seismic.