preengineered building foundations uplift

[tpmanzi]

I typically use 2 layers of rebar in my footings which resist uplift and have been asked not to use upper layer. Does everyone use 2 layers? If not how do you resist top of slab bending during uplift situations?

 

[msquared48]

If the anticipated uplift moment did not incur moments in the footing that would exceed the cracking moment, I would say eliminate the top steel. OR...

Another approach with one layer is to position the one level of steel in a footing of sufficient thickness that the steel works fine for uplift or gravity loads.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[hokie66]

If the footing has to resist uplift, it needs to be designed for that case as well as for the downward loads. You wouldn't consider deleting the bottom bars if asked to do so, so if you need the top bars, why not just explain that to whomever asked for the deletion?

 

[Ron]

I keep top and bottom when the footing is subject to uplift and overturning moments. Keep in mind, as hokie66 noted, the loads are reversible.