I saw soil shear figures varying from 10% to 50% of compression strength. 10% makes sense to me, so I'm using 150 psf here. The structure is rigid - think of it as a universal design of a table-like structure sitting on 4 legs, on piers embedded 3' into the clayey ground. Subject to straight...
"Retrograde" - just assuming 1,500 psf clayey soil
"phamENG" - thanks, but I'm afraid I disagree. With a factor of safety to account for irregularities, soil weight and lateral pressure is taken into account for uplift resistance. The entire industry of prefab small buildings relies on that.
I...
Zero uplift resistance from soil cohesion and pressure - hmm... by that thinking most decks, prefabricated sheds, and similar structures, would be flying with the wind. By that thinking you'd just pick up a 4x4 post fence out of the ground, while the reality is that you could not unearth it...
Hi guys,
Concrete pile-type footings (for individual metal posts of a structure), 16" dia cylindrical, 36" below grade (6" above grade). Soil is clayey silts. Is there a simplified way to estimate the uplift resistance strictly due to soil's lateral pressure and cohesion to the concrete...
rb1957 - thanks. (First of all I always avoid straight steel as I don't see the point of building with something that would start losing its strength and deteriorate / rust right away, or require high maintenance). My reasons to really like 6061 is its incredible relative strength, lightweight...
Yes, stiffness - that's why I was so incredulous at aluminum's "strength" in the first place. Ballpark I would always think about steel as generally 3x "stronger" than aluminum, but isn't it inappropriate to think in modulus and involve strain here? Strain in aluminum being higher than steel's...
Thanks! After years of being in love with 304 and other ss steels, I'm leaning more and more toward 6061 (T6). True, yield point is less well defined. and I shall further research the books for a safe figure to use. To simplify the original question to shear only though: say, a 1/4" thk alum...
Hi guys,
I don't deal with this every day as an architect but can anyone please clear up my confusion regarding the yield strength of these 2 metals above? I'm getting 35ksi for the aluminum and about the same for the ss steel, which cannot be. And then do you take the working Fc=Ft=Fv all at...
Thank you all. A well-defined mechanical resistance is always preferable but this is an as-built situation and, as I said, I needed to determine any possible strength from cohesion as well. Your numbers above vary greatly, from 25 psi to 82 psi.
Meanwhile, I have a hard time convincing myself...
Thanks STrctPono, cohesion makes sense (and thanks retired13 - though not sure what you mean by "positive"; isn't the cohesion strength positive too? Btw, I do have a rod at the end but I wanted to isolate the problem in order to calculate the total embedment pull strength).
I still wonder...
Hi guys.
Flat (i.e. smooth) steel plate, or tube, embedded into concrete footing. Say 3" wide x 1/4" thk and a 24" vertical embedment. Does anyone know of a method to calculate the maximum pull out strength (force) of the steel plate out of the concrete? They say to use a 0.7 friction...
