HSS Column Within Exterior Stud Wall - Foundation detail

[edled]

In the last two years I've started to do a lot more residential, both steel and wood frame. One situation I keep running into is having an HSS column within an exterior stud wall (sometimes the studs are load bearing, sometimes not) at the request of the architect. When you get down to the ground floor, we typically have a curb that the studs land on, about 1'-0" or so above T/slab. I see two options, neither of which are totally satisfactory:

1) Have the column land on a pier, T/pier = T/curb. The issue with this detail is that the pier will jut into the interior space, and avoiding having it jut into the exterior space requires a pretty eccentric base plate.

2). Have the column land on a dropped pier, T/pier = -1'-0" below T/slab or so. The contractor comes back later to do the curb pour. However, depending on the size of the HSS column, it will barely fit within the curb, an HSS4x4 in a 6" curb will only have an inch of "meat" each side. Seems like a recipe for some spalling.

Any other thoughts on this? Is there no way to resolve this in a way that makes everyone happy? I come from the world of much bigger projects where your W12 and W14 columns are never going to fit in the wall anyways so this has never been an issue.

See the attached image for a typical architectural section. I guess I should clarify that this is really only an issue when a curb is needed, but that's fairly often on my projects.

Thanks in advance,
EL

 

[jerseyshore]

For things like this, I first see if I can make an anchor bolt on each side work in the stem wall. If that works, great. If not, you give them the option of bumping the wall out or running the column all the way down. I'm assuming this is just a garage so I wouldn't think a small bump would be a big deal.

 

[phamENG]

I also don't love it sitting up on the curb, though it can be done and I've done it as jerseyshore describes. I usually just detail it all the way to the footing. If you're concerned about spalling, have them run some wire reinforcing past the column on the exterior face.

jerseyshore - for me, this usually happens in living rooms or great rooms with 18 to 20 foot ceilings and large windows looking out over the water.

 

[edled]

jerseyshore - Yeah landing on the curb with two bolts and no pier is an option if there's not much load in the columns. Sometimes these are columns picking up several floors of load though and I feel better having four anchors and an actual pier in those cases. Regarding a bump out in the garage, often that's where we're tightest for space, and as phamENG mentions, we often have a curb at an exterior wall even at non-garage interior spaces.

phamENG - good idea with regards to the mesh, thanks.

 

[jerseyshore]

Can't remember the last time I saw a curb like this inside the main part of the house. Honestly slab-on-grade houses are incredibly rare in NJ. Haven't worked on a new one in years. Good to know.

 

[phamENG]

We don't usually have it come up like that - just stops at the slab level. But the condition is similar. Also, we don't use concrete. All foundation walls here are CMU.

 

[edled]

Yeah this is more for four/five over one apartment buildings

 

[Eng16080]

Be careful if you decide to only use 2 anchor bolts. Depending on the weight of the column, 4 might be required by OSHA.

I've often used curbs (stem walls) like this on projects where the outside grade exceeded that of the floor level. Usually in my case, though, the wall doesn't bump in to be hidden within the wall thickness.
Rather, the wall bumps out a little where the concrete is.

If you're concerned about the column load being resisted by a thin concrete wall, you can make the base plate extra long and use stiffeners. That will distribute the load over a greater area.