Keyed Footing/Stemwall

[medeek]

I have a residential client that would like to key his footing / stemwall versus install vertical rebars. I've never called out a key way on any of my architectural or structural drawings. I was of the opinion that no one does this anymore and everyone just uses #4 bar verts @ 24" o/c or some other spacing.

I've got a standard 24" high stemwall, 8" thick with a 8x16 footing. Does anyone have a typical detail showing a keyed joint given this criteria? To properly engineer this I should probably call out the width and depth of the key but I'm wondering if other engineers go to that level of detail or not. I've found in the past that when I encounter something new like this I often over shoot the mark because of my inexperience.

A confused student is a good student.
Nathaniel P. Wilkerson, PE

http://www.medeek.com

 

[medeek]

Interesting article on the subject. It would appear that a 3.5"x1.5" shear key would be pretty typical.

https://www.google.com/url?sa=i&rct...wipjPf65-LNAhUI4mMKHQvOAHwQjB0IBA&url=http://

http://www.concreteconstruction.net...cvKS7qjMt6y60DQ942rw7AkA&ust=1468031010288614

A confused student is a good student.
Nathaniel P. Wilkerson, PE

http://www.medeek.com

 

[Guastavino]

Company I used to work for did the 1.5x3.5, i.e. A 2x4 for shear keys. I think they still do them

 

[jayrod12]

Ya a 2x4 as the keyway for work is fairly typical. I'm surprised that's what the client wants to do. For a while there we were showing keys and getting asked if we can omit it for additional dowels.

 

[hokie66]

I suppose this is done by some prescriptive code, but I have never understood why anyone would cast a wall without reinforcement.

 

[MotorCity]

It is interesting to see how practices vary by location. Here in the Midwest, my experience has been that residential walls and footings only have a shear key formed by a 2x4 without any reinforcement between the wall and footing.

 

[BUGGAR]

I met a drafter who said he was taught that a shear key shown on a drawing was actually a symbol for a cold joint!

 

[medeek]

Apparently some people still like this method of construction. The clients argument against the verts is that the moisture/ground water will seep in between the cold joint between the footing and stemwall and eventually corrode the exposed (uncoated) rebar. Being that this is Ocean Shores and the residence is right next to the beach this ground water will probably have some salt content, I've noticed from other jobs that the water table is quite high in a few places (2-4 ft. below grade) and coincides with the tides. So maybe there is a valid argument here.

A confused student is a good student.
Nathaniel P. Wilkerson, PE

http://www.medeek.com