Wood Members Supporting Earth Pressures

[HauerEng]

I'm an engineer in California using the '19 CBC and the AISC 7-16. Is there a reference in those codes/standards prohibiting or allowing the following for resisting retaining wall earth pressures:

Horizontal plywood diaphragms?

Plywood shear walls?

Thanks in advance,

HauerEng

 

[HauerEng]

Checking to see if I am getting replies- Someone please "reply".

Thanks!

 

[jayrod12]

I can't speak to California as I practice North of the border. But up here, we have a specific standard that deals with preserved wood foundations. Wood floors at both the main floor and basement levels help transfer the backfill loading across the building to the other side.

That being said, PWF foundations are generally only done for the most basic of building layouts.

 

[r13]

1807.2 Retaining Walls

Retaining walls shall be designed in accordance with Sections 1807.2.1 through 1807.2.3.[OSHPD 1R, 2 & 5] Freestanding cantilever walls shall be designed in accordance with Section 1807.2.4.

1807.2.1 General

Retaining walls shall be designed to ensure stability against overturning, sliding, excessive foundation pressure and water uplift.

If you can design the wooden retaining wall to meet strength and durability requirement (including stability), I don't think there is prohibition for using wood as foundation material. However, do check with local jurisdiction for the acceptance of such application.

 

[XR250]

This is pretty much how most houses with basement work. Is your retaining wall constructed from wood? it is not clear from your post. Also, if it is braced top and bottom, they are typically called "basement walls"

 

[HauerEng]

I guess I should have been more specific- my retaining walls are masonry- not wood. And, I see the point, that if it is a basement with a wood floor above, the wood floor would act as a diaphragms to transfer forces to the perpendicular basement walls. So, I guess the codes, (IBC/CBC), allow wood diaphragms to transmit horizontal earth pressures.

But what if the walls perpendicular to the retaining wall are wood? Can wood shear walls be used to resist earth pressures??

Thanks again,

HauerEng

 

[r13]

But what if the walls perpendicular to the retaining wall are wood? Can wood shear walls be used to resist earth pressures??

If you are thinking the floor diaphragm will work, why not the wood shear walls, which do not directly in contact with the soil? I don't quite understand your question/concern.