Brace Footings
Brace Footings
(OP)
I have a building that is concentrically braced with some large uplift loads. The building is not very large only 90'x40'x56' (LxWxH). The large loads are due to narrow bracing limits (13'-6" wide).
To resist the overturning forces of the brace, I will place large footing under the brace that will satisfy the code overturning requirements (essentially mass concrete). Does anyone else have a better way of handling this problem? My way seems really inefficient.
To resist the overturning forces of the brace, I will place large footing under the brace that will satisfy the code overturning requirements (essentially mass concrete). Does anyone else have a better way of handling this problem? My way seems really inefficient.






RE: Brace Footings
Mike McCann
MMC Engineering
RE: Brace Footings
Would continuous footing helps (along the 40' edges)?
RE: Brace Footings
I am leaning towards msquared48's grade beam idea. I have to play with the column locations to make it work. I had previously thought I could play around with the steel detailing to reduce the seismic loads on the building (use a SCBF R=6 instead of R=3) but once I did this wind quickly became the controlling factor. Actually the wind overturning is as much as the seismic. For most I my buildings seismic is the controlling lateral load.
My existing braces are 10' in from the end walls of the building (buried in the stair openings). So the end wall grade beams/frost walls are of no help. In one location I am near the elevator so I have to drop the footing another 4' (to the top) to get the footing in.
I just can't believe that I need a 40' long grade beam/footing to stabilize the footing against overturning. Seemed inefficient to me.
RE: Brace Footings
RE: Brace Footings
Mike McCann
MMC Engineering
RE: Brace Footings
RE: Brace Footings
Attached is a quick sketch of the plan.
RE: Brace Footings
The elevator shaft possess some geometric challenges, can you shift it a few feet north?
RE: Brace Footings
Another alternate would be to look at adding some mini piles, tension anchors etc. It would not be a bad idea to check with the geotech engineer for local practices and suggestions.