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Re: uplift in footings

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Luckily, you can take a 0.75-0.8 x Windspeed in construction period cases (~.55-.65x windforce), before the slab gets placed, which should bring you down into the DL region of the footing itself plus non-compacted fill on the footing (say 80% density and 0 degree line).

I'm still looking for pictures of an intact, or mostly intact, PEMB flipped over with the footings pulled out of the ground. I'm also looking for specific evidence of tensile failures using lapped bars and/or hairpins lapped to WWR in slabs, where the slabs have not been damaged prior to the failure (i.e. sawcut completely through). Any takers?

Jordan



Gary L. Hodgson and Assoc. wrote:
Andrew,
I became very concerned about uplift on pre-eng buildings a few years ago, so I tried to do a bit of research and found very little information. What little I found was that if you are located in cohesive soils. you should use an angle of 30 degrees from the vertical (assuming that failure would occur on a 45 deg line) and in non-cohesive soils to use a smaller angle, but not to exceed 20 deg from vert. These recommendations were based on no slab in place, as could occur when construction is not complete and you may not have all the dead load in place and no slab yet. Hope this helps.
Gary


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