HSS column base plate on CMU foundation wall detailing

[TroyD]

Just looking for some input on a foundation detail (attached). I'm structuring a commercial building (bank), single story, wood framed on 8" CMU foundation wall, 42" frost depth footings. Nothing too unusual or complicated, but the amount of windows, and a parapet height of 18' at one end wall, leaves very little wall segment for resisting lateral loads with shear walls. One building corner has a large bank of windows each direction. I intend to place a HSS column in that corner and header those windows with a W8 or W10. There is a small vestibule, mostly windows, that I intend to frame with steel also.

Please note my foundation section shows a 6" CMU top course, with 8" block below. This is common practice locally, with the floor slab over-poured on the 2" ledge. My main concern is the column base plates with embedded anchors extending thru the 6" CMU top course into the 8" block below. Is this detailed correctly? I would prefer 4 anchor bolts for each base plate, but the 6" block width doesn't really allow for it. I labelled the second course of block as a bond beam. The anchor embed depth has not been determined...might need to go deeper, possibly down into the footing.

Any feedback/input is appreciated...

 

[JAE]

OSHA requires minimum (4) anchor rods at columns so you'll have to create a masonry pedestal below (16" x 16" or larger) to facilitate these anchors and drop the base plate 8" to the lower level to hide the larger base plate.

If the column has lateral shear, you also need to make sure that the anchors won't get blown out the sides of the masonry.
Deeper anchors would be needed to allow competent development and anchorage of the top course of 8" block (I'd ignore the 6 inch block totally.


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[JAE]

OSHA Link:

https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.755

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[sandman21]

Sounds more like a post than a column and would not need four bolts. Link.

OP your question will very much depend on the loads the post would need to transfer. If loads are large it will be an issue to transfer the loads through the 6" CMU

 

[JAE]

Hmmm...well if the "posts" only hold up the window headers (vs. the roof framing) then maybe a post. If not - a column.

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[jayrod12]

I was under the impression you could still have 2 anchor bolts on a column, but it would require the erector to provide additional temporary bracing during erection.

 

[JAE]

I asked that question of OSHA last year (about temp. bracing) and they said no. I couldn't understand that response but that was what I got.

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[TroyD]

I could make the base plates longer to allow for 4 bolts.

 

[jayrod12]

And that's the solution I've used before, however technically 4 bolts in a line is no better than 2, and I'm not sure about south of the border and overseas but here they have some requirements about bolt pattern.

 

[TroyD]

I structured a new Burger King shell about 18 months ago here in the Midwest. BK provides template CAD drawing files for architectural, structural, and MEP to speed up the design. The modern BK storefront is almost entirely windows, so they call for a 'moment frame' with a series of HSS columns and W-beam headers. Looking back at the plans, those column base plates had only two bolts embedded in the concrete foundation wall, but it was at the building end wall, not supporting roof trusses, only wall dead load above the windows.