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Bearing beams from new canopy on existing CMU wall

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mfstructural

Structural
Feb 1, 2009
230
I am designed a steel canopy that is 60' long and 24' wide. The canopy will be up against an existing CMU building. The CMU is 12" and the 60' long section will be up against the building. I'm planning on 4 columns spaced at 20'. Wanted to get people's preferred method of attaching steel beams to an existing CMU wall. I'm contemplating knocking out part of CMU and bearing on a grouted stud plate, or through bolting (bearing on CMU) or anchoring to face of CMU. The reinforcing/grouting pattern of the existing wall is unknown so there would have to be a note on drawings to verify if cells are grouted. Do you typically add a note to verify that reinforcing is also installed in the cell at beam bearing? I feel that it is hard to coordinate that and if there isn't a bar not really feasibly to add one.

One issue I have with this canopy is that a steel WF beam is bearing on the CMU at the interior within a foot of where a canopy beam is located. The reaction from the existing beam is 24kips and the reaction from the new canopy beam is about 10kips. I want to avoid knocking out any CMU or bearing near this existing beam but wanted to be people's thoughts. I can provide some photos if needed. There is also a height issue that might dictate the beams be mounted higher which could interfere were steel bar joists located adjacent and parallel to the subject wall.

I'm debating on adding 4 columns against the existing CMU wall with isolated ftgs doweled into existing foundation. This will avoid adding load near the existing beam and also any potential interferences with the bar joists. The columns can be attached to the CMU with angles for lateral stability. or a ledger along top of canopy to attached to.

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I've done both options before and I usually like adding new columns just off the existing structure.

You space them just off the existing building and have the beams run over top (short cantilever if necessary).

Adding a steel building addition or canopy next to an existing masonry building is always tricky because it's just so much more flexible than the CMU. I've seen many a building steel damage masonry walls by moving too much. And here you have a ton of uplift from an open canopy I wouldn't even bother trying to make that connection.

Leave the old building alone and design a new frame right next to it with a little space in between to avoid any potential damage.
 
Mfstructural:
What about 24' long bar jsts. with a 3' canti. top chord at the open side? The jsts. would be pocketed into the existing 12" conc. blk. wall and would distribute the new roof load much more uniformly to the existing wall and footings. Remove a couple blks., outer shells and cross shells only, ever 5 or 6' to work on grouting and brg. pls. and then rough infill around jst. brgs. Can they take this new roof load? You will likely reroof up and over the pockets and have to remove the existing wall cap to do a proper roofing and flashing job anyway. Grout some conc. blk. cores under each jst. brg. and set a brg. pl. which will distribute both gravity and lateral loads into the wall.
 
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