Steel Beam to Poured Wall Connection 5

[Bammer25]

Hello gentlemen. Hoping you can help me out with the best way to look at this.

I have a client building cabins on steep slopes in the mountains here in East Tennessee. There have been a number of these done by others, so we are taking their design as a starting point and I will model it and size everything.

Anyway, the cabin will be wood construction, but will sit on a steel frame on "stilts" down to concrete foundation. I attached a sketch. Basically, the steel frame will capture all load points and distribute to columns. Most the exisiting ones have a single column at the mid point of the structure with knee braces for stability. Plenty of plan bracing underneath.

My question is the best way to connect the main beam to the concrete wall, which serves as a retaining wall and "basement" wall for the bottom floor. It seems like casting anchors into the wall with an embedded plate and shear tabs welded on would be a bit difficult to construct, and then I am relying on those anchors to ensure the building does not essentially fall down.

Would you have a thickened area as sort of a beam pocket? Anybody have a typical way to deal with this, or is the embedded plate idea the best way?

 

[Bammer25]

The connection is called out as Detail 1

 

[phamENG]

All depends on the contractor. For a residential job, I agree that complex connections that require significant coordination may not be the best idea. Unfortunately you may not be able to avoid it here. The issue is the retaining wall continuing above. A few options I can think of:

Block out a bearing pocket for the beam. The issue here will be accessibility to make the connection.

Provide a corbel as a bearing seat. This is a bit complicated in terms of concrete construction and may be beyond a lot of residential contractors.

Create a pilaster to sit the beam on. Easy to detail and construct, but adds to the form work and may be seen as 'over conservative' by the contractor.

Cast in a connection. Relatively easy, but the coordination may be beyond the skills of a typical residential contractor. Look at precast here - there are some nifty connection embeds that allow you to fasten the product to the form, cast the concrete, and then bolt the beam to the embedded connector. One popped up in a thread recently but I don't recall the name.

Here's a document you may want to review for some inspiration: Link

 

[Bammer25]

Good stuff thanks. I like the idea of a pilaster. I am not worried about the contractor in this case pinching pennies. He’s all for being conservative in the name of safety. He also has it sold already for a very large profit.

 

[kipfoot]

A possible benefit of the pilaster idea is that you could run a beam parallel to the retaining wall that sits on pilasters and would give you some flexibility in where the lower columns are placed. The columns wouldn't have to be in perfect alignment with the pilasters because you could connect to that beam anywhere along its length.

(also, not to overlook the obvious: I assume you've figured out the lateral load resistance for the retaining wall and it's not shown in the sketch)

 

[271828]

If you decide to go with an embedded plate, I'd recommend a double- or single-angle connection instead of the shear tab.

If the angles are welded to the plate as indicated in the AISC Manual Part 10, the eccentricity on the plate and studs will be so small you can neglect it. With shear tabs, you'll need to deal with the eccentricity and you'll probably also want long slotted holes, which will throw you out of Table 10-10.

 

[Bammer25]

Good idea. Thanks

I am leaning heavily toward the pilaster idea. That should also stiffen the wall up a bit

 

[XR250]

1) That wall is retaining a bunch of backfill. The footing you show does not seem proportional to how big it needs to be.

2) Why not bolt a plate to the wall and weld clip angles to that?

 

[BAretired]

I would be more concerned about the stability of the structure than the detail mentioned. The sketch does not indicate much lateral resistance to the pressure from the retained granular fill below the driveway.

BA

 

[Bammer25]

Of course I will design the wall and the footing to take the lateral pressure. I just wasn’t sure if asking a poor guy to bolt that beam to a welded clip was asking too much for a residential contractor. A pilaster would provide a nice shelf for bearing along with strengthening the wall

The embed would be far cheaper

 

[kipfoot]

you could also form a beam pocket that would make it pretty simple for the framer.