Ledger Channel on Brick Wall

[RareBugTX]

Hello all:
Working on a project where we are relocating an entire floor 18" above the existing level (one story bldg with basement. Basement to have a higher ceil) Previous system was wood frame on steel beams. Now we will have noncomposite concrete/Steel deck supported on new steel beams and columns, footings. Max span 12.5' or less.

Question is, at the wall the deck support is been proposed a steel channel (6") as a ledge anchor bolted to exist 8" brick wall with ABs spaced per calc. Now whats the controlling factor? In my view is just ABs pullout from wall. Bearing and shear on bolt dont think is an issue (thinking 5/8" ABs) Anybody done any check on bottom of channel flange? Bending? Or anything else? I see it as simply supported on such bottom flange and spot welded deck to web. Any feedback, thoughts, ideas or sample calc resources would be appreciated.

Regards

RateBugRA

 

[SLTA]

How old is the building? You may want to do a check on the capacity of the brick and mortar, if it's over about 50 years or so. The loads can turn into lateral issues - it's less bearing and more shear/pullout. I've done this on several historic buildings and we always pocketed in the new beams on a steel bearing plate and packed around the new pocket with grout.

Just yesterday, I looked at a floor that had entirely collapsed because someone did a similar idea with wood and nails. Not saying this won't work better, but I've always been leery of just anchor bolts to an unknown entity, like an old brick wall.

 

[JAE]

Agree with slta - also a few other thoughts:

If you bolt a channel to the face of the 8" brick wall, you have a number of checks to perform to ensure you are OK.
1. Bolt shear capacity (based on an assumed f'm) using ACI 530 or using documented/approved post-installed bolt capacities from companies like Hilti.
2. Channel span capacity (spanning between anchor bolts) - probably not an issue.
3. Eccentricity of floor load on the wall below. The wall will have roof load, lateral wind/seismic loads, and now the eccentric floor load (also maybe lateral earth pressure below?) All of these load combinations should be checked against the wall's capacity - again based on an assumed or prism tested f'm, which for old brick could be very low - 500 psi or so?

I'd also be concerned with local "bad spots" in the brick where loose brick, powdered mortar, etc. occur.

It may be more desirable to build pilasters (either masonry or steel columns) against the existing wall, on top of new footing extensions, and then span the new floor beams onto those supports, bypassing the wall as a support. Then tie the wall into the new floor for lateral and shear wall type connections.

I would presume that the current load application from the floor is via pocketed joists - which means the original floor placed far less eccentricity on the wall.

 

[RareBugTX]

Very valuable feedback!! Thanks. Building should be around 50-60 years old.Brick looks solid, but will definitely use the proposed conservative numbers. slta, and JAE, thanks a lot.

 

[dhengr]

I agree with what slta and JAE have already suggested, but why not add some 3x3x8" angles grouted into the mortar joints, say every 3-4'. Weld the channel to the vert. angle leg. That way the bolts will mostly just be tying things together laterally, and not applying large vert. point loads to the brick.