unreinforced concrete slab
unreinforced concrete slab
(OP)
Can anyone tell me the procedures, assumptons, and formulas to use when checking a thick unreiforced concrete slab. I am thinking that if the slab is thick enough you just need to check the shear values because the tension steel will not develope. Is there a ratio of length to depth, or other guidlines on when this assumtion is correct?
Any help would be greatly appreciated.
Thanks
Any help would be greatly appreciated.
Thanks





RE: unreinforced concrete slab
RE: unreinforced concrete slab
RE: unreinforced concrete slab
Thanks for any input.
RE: unreinforced concrete slab
RE: unreinforced concrete slab
On a different note you say you have an existing slab with uplift. That puts the tension face on top which should be readily inspectable. Pay careful attention to any visible cracks espicially any running perpindicular to your span direction.
RE: unreinforced concrete slab
RE: unreinforced concrete slab
RE: unreinforced concrete slab
Thanks all
RE: unreinforced concrete slab
RE: unreinforced concrete slab
If you don't develop any support restraints you're slab will move like a rigid body and will not have any stresses at mid section.
And depending on the depth of the seal it could be reasoned out that moment is transferred to the sheetpile/soil or in a conserative fashion, the edges are simply supported.
You'll need a steel/concrete bond stress that is reliable for your calcs.
Lastly, with the depth of the seal (as is the case for most seals)being significantly deep relative to it plan dimensions you may not develop bending stresses at all. At this depth it may act like a shear slab.
Regards,
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RE: unreinforced concrete slab
RE: unreinforced concrete slab
RE: unreinforced concrete slab
Where in Section 22 is the modulus of rupture given?
RE: unreinforced concrete slab
the modulus of rupture is on page 345 (ACI 318-05) equation 22-2. It says Mn=5(f'c^0.5)*Sm. Therefore, modulus of rupture is 5f'c^0.5.
All-
Am I missing something here. I would think that in order to get a slab to work unreinforced, it would have to be relatively thick. Once you start making it that thick, the DL is increasing, causing you to increase the thickness more. It seems like a never-ending cycle. I have never designed an unreinforced slab, but it seems kind of scary to me.
Possibly if the spans are very short and the joists are reinforced I would feel better.
RE: unreinforced concrete slab
It seems to me that the weight of the slab increases linearly with depth, while strength increases with the square of the depth. It should be self evident from here.
RE: unreinforced concrete slab
RE: unreinforced concrete slab
Can someone please help me to see the value in this type of system?
RE: unreinforced concrete slab
RE: unreinforced concrete slab
Plain concrete is good, for a common case, to show that a residential footing, or any sufficiently narrow or deep strip footing does not need cross bars, i.e. bars perpindicular to the longitudinal axis of the footing. As the OP teaches us, it has uses elsewhere too.
RE: unreinforced concrete slab
RE: unreinforced concrete slab
RE: unreinforced concrete slab