slab-on grade stress due to shrinkage
slab-on grade stress due to shrinkage
(OP)
Can anyone suggest how to calculate the stress in a slab-on-grade due to shrinkage?
The common method of relating frictional drag to stress in the slab does not seem to account for the difference caused by concrete mix with low vs. high shrinkage strain.
I am interested in comparing the shrinkage stress in a slab-on-grade made with 0.07% shrinkage concrete mix with that made with a 0.04% shrinkage starin concrete.
The common method of relating frictional drag to stress in the slab does not seem to account for the difference caused by concrete mix with low vs. high shrinkage strain.
I am interested in comparing the shrinkage stress in a slab-on-grade made with 0.07% shrinkage concrete mix with that made with a 0.04% shrinkage starin concrete.






RE: slab-on grade stress due to shrinkage
I've always looked at it more as a volume change problem then a stress problem. Once you get to concrete rupture, you get a crack regardless of rebar.
As for volume change, I've used the PCI manual for rough numbers and considering the top surface to volume ratio only.
RE: slab-on grade stress due to shrinkage
RE: slab-on grade stress due to shrinkage
RE: slab-on grade stress due to shrinkage
Normally I design my slabs ignoring stress from thermal and shrinkage for flexural stress (unless it is un-jointed). I then detail the slab to release the stress build up due thermal and shrinkage stresses.
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RE: slab-on grade stress due to shrinkage
RE: slab-on grade stress due to shrinkage
For your issue, I would take a more practical approach.
The stress/strain curve of the two concretes you are comparing are likely similar. I would equate the shrinkage percentage to a linear strain, neglecting volumetric strain (or you could equate with Poisson's ratio, 0.15). Then you only have the differential strain to deal with. Bracket the stresses with your different stress/strain curves and you'll get a reasonable estimate.
RE: slab-on grade stress due to shrinkage