I sometimes check use Ig with service loads, if that exceeds the rupture than I assume it is cracked.
Some things I do by inspection for example a concrete column because it lives in compression or the compression area of a beam for the same reason. These areas are typically in compression at ultimate as well.
Also, PCI says the CCD method is based on cracked concrete at service (installion) so I guess it is a fudge factor to bring in line with test results.
A concrete column only lives in compression if it is above the decompression line on the interaction diagram for all load cases. There may be some instance where stresses in the column do become tensile.
I thought appendix D of ACI had to do with anchoring into concrete.
When checking deflections, I never use Igross. I also reduce it up to 0.6Ig.
App. D is about anchoring to concrete. I was asking why concrete cracking at service levels matters when App. D is dealing with ultimate loads. Why wouldn't cracking at factored loads be more appropriate?
Ash was merely making reference to a situation he felt would qualify as uncracked concrete.
