Basement Wall Top Restraint - Wood Framed Building

[skired]

I am designing a wood framed building with a 12 ft basement, retaining about 11.5 ft. The first floor framing sits on an interior shelf in the concrete basement wall.

What load path do you typically use to restrain the top of basement wall and transfer the lateral earth pressure into the first floor diaphragm? Are you sizing sill anchors to transfer the load? Wall bearing on the first floor framing?

 

[lexpatrie]

Curious, do folks consider this a pinned fixed wall?

At least I understand the 425 x 9.25 / 32 = 122.8 plf.....

Hang on, I think Internet Archive just dropped Roark's from the free to look at feature.

 

[jerseyshore]

We typically use 50 psf/ft for basement walls, but regardless, we almost never design them to span horizontally. Any horizontal action is a bonus.

And to your point XR, I've never looked at the blocking uplift like that, no. And honestly 90% of the time when I am drawing that detail it's for a basement wall repair so a hump in the floor is the least of their concerns when compared to the wall bowing/ pushing inward.

 

[DoubleStud]

If you don’t use horizontal span, then why do people use counterforts? Aren’t they essentially to break the horizontal span?

 

[jerseyshore]

Pilasters and other similar supporting elements are specified in the IRC so lots of architects/ builders will add them in new CMU wall designs. They are fairly common in older NJ basement walls so that construction technique has stayed in practice, albeit much less frequently these days with finished basements in all new houses.

It's not something I've seen any engineer specify around here since every new CMU wall is properly reinforced to span vertically (unlike the old days).

 

[lexpatrie]

Where in the IRC is there a pilaster?

 

[jerseyshore]

R606.6.4 is lateral support of masonry walls. Mentions different horizontal supports including pilasters. It's what I see architects and building officials reference.