Horizontal Mezzanine Bracing Force Resisted by Slab at Base 1

[waytsh]

I am designing the footings for a fairly large mezzanine and am looking for a better way to resist the horizontal component of the seismic bracing force in the braced bays. The columns extend through the slab and sit directly on the on the top of the footing without any pedestal. I normally would have tried to tie the bottom of the column into the reinforced slab somehow to keep the footings a reasonable size, however, because the columns run through the slab I do not know of a good detail for transferring this force.

Any suggestions?

 

[waytsh]

Rather than using some type of hairpin in tension I have decided to check the bearing of the slab against the column and use that allowable compression value to resist the horizontal force. Does anyone see any problems with this strategy?

 

[lkjh345]

FWIW:

I do this on some jobs as well. I check the bearing of the column flange (or sidewall if it is a tube column) against the concrete slab. If the horizontal force can be transmitted this way, then I assume the friction force on the bottom of the slab can be used to help resist the horizontal brace force.

Recommend placing a bond breaker between the column and the concrete so the footing can settle without dragging down the slab, and reinfoce the slab around the column so you don't get shrinkage cracks comming off the corners of the column.