Haunch Capacity

[XR250]

We thought the wall was solid the entire way to the footing. Turns out there is a haunch. My demand is 3.8k service. The EOR wants us to cut thru the haunch and bolt the column to the concrete wall below using a plate. I don't do much R/C design but my gut says this should be able to handle 3.8k. What are y'all's thoughts?

 

[phamENG]

It could probably do it, but I'd be hesitant. Looks like it's just there to hold brick veneer, but the veneer never got built. Without knowing the size of the bars, their spacing, and their anchorage (I've seen some pretty sketchy corbels), I'm not sure I'd be too excited about using it.

 

[Enable]

Sounds like EOR is saying to bypass the corbel pham. Cut and add plate directly to wall below with HSS / column presumably face welded (or alternatively an angle underneath I suppose). 3.8kips is very easily accommodated with a plate / Hilti KH-EZ screw anchors to the wall below.

EDIT - Sorry I misunderstood. You want to use the haunch, EOR says go to wall. Yeah, I prefer EOR for reasons a la pham.

 

[TRAK.Structural]

Depends on if the haunch/corbel was cast monolithic with the wall, or a separate pour after the wall was done. ACI has some pretty intense detailing requirements for corbels; this is so small that I doubt there are any bars in it (or at least nothing substantial). Personally I cut through the corbel as requested by the EOR.

 

[XR250]

Thanks y'all. The EOR has not wanted to check things in the past so this may be another case of it. Who knows? I guess we will cut it.

 

[phamENG]

Thanks y'all. The EOR has not wanted to check things in the past so this may be another case of it. Who knows? I guess we will cut it.

I can see that. How much labor is it, really, to cut it in one spot? It's probably a wash, cost wise. Unless, of course, that's a 10ft basement wall and this would save on the excavation and 10ft of steel column.

 

[KootK]

That would be a tough one for me. My personal, first rule of renovation is Hippocratic in nature: do no harm. Or, more accurately, do as little harm as possible.

I kind of worry that in chipping away the corbel, you'll be left with a dog's breakfast of a situation with rough concrete, post installed bolts with a bit of a standoff, and concrete that is full of a bunch of unpredictable microcracking.

Trading all of that against a healthy looking bearing condition doesn't feel super awesome to me, even if it's cleaner analytically (which it is).

The assessment method shown below is something that I've done in the past. One of my old mentors even had an excel sheet that would check flexure and shear friction on every conceivable failure plane in an automated fashion. It was cool but, fundamentally, I don't find that any more convincing that what I've shown below.

I certainly don't fault the EOR for their approach given the uncertainty involved in evaluation.

How would the base of the column be fastened to the haunch? I would want some confidence that the fastening itself wouldn't beat the thing up too badly.

 

[CANPRO]

Can you put the column on the ledge and infill below with some concrete? Easy formwork and not a lot of concrete; size the dowels to get the 3.8k back into the wall. You get easy column install, EOR gets nice continuous load path. Everyone is happy.

 

[human909]

I'm pretty green in this sort of thing so feel free to shoot down my thought bubble. But along Kootk's line of do no harm, why not epoxy some reinforcing dowels in? Again gut feeling 4 x N10 (10mm reinforcing) or your local equivalent. Expoxied in 30mm, and 60mm from the top.

3.8k? I presume you are speaking in pounds so that is only 17kN. Which is pretty minor as you've already recognised.

 

[XR250]

Just got word we can bear on it with some limitations on min. base plate size and max. anchor depth.
Don't have any uplift so I will specify some small epoxy anchors.
Thanks for everyone's responses.