Thanks all for your input. I see now that it is possible for Mcr to be greater than phiMn when you have a small d, such as one mat of rebar centered in a wall.
Does anyone have insight as to why ACI 14.8.2.4 exists? Why are we trying to reinforce a wall to prevent cracking?This seems to contradict the rest of 14.8, where deflections are a function of Icr. There is no commentary given on this.
I agree with Dave - use the cantilever reaction if the wall is continuous past the diaphragm. Statics are statics.
If, on the other hand, the wall is discontinuous at the diaphragm (which you might have with interrupted studs which are kicked back down to the diaphragm), then I would use 1/2...
His lame excuse was that he relied on the minimum weld size called for in AISC. We told him that AISC doesn't cover welding of rebar, but since AWS D1.4 doesn't cover weld size either we didn't have anything to back up our position.
We typically have not called out weld size for welding rebar perpendicular to a steel plate (e.g. embed plate); instead we've always referenced AWS D1.4.
Recently, a steel fabricator sent thru a change order because he had to increase the weld size per our marked-up shop drawings. Researching...
