I have seen control joints detailed with just a saw cut (usu. 1/5 to 1/3 of slab depth) and steel continuous, a saw cut with every other bar cut, and a saw cut with the steel discontinuous.
I'm relating to reinforced slabs on grade in Florida; we have primarily 2 types: 4" with WWM (standard) and 6" with rebar (heavy loads or differential settlement).
It seems exceedingly rare that discontinuous steel, or every other bar/wire cut occurs at the actual saw cut location. I also cannot see how not cutting the steel would restrain the crack. When the slab shrinks it puts the slab and the steel in tension. Even with #4 bars @ 16" in a 6" slab, the transform area of steel to concrete is only 1.35 sq in./ft, which is much less than the 1/5 of the slab depth (14.4 sq in./ft) and should effectively weaken the slab to illicit a crack there.
Are these details stopping/cutting the steel just archaic, or is there a concept I have missed? What depth do you use (1/5 is our standard)?
I'm relating to reinforced slabs on grade in Florida; we have primarily 2 types: 4" with WWM (standard) and 6" with rebar (heavy loads or differential settlement).
It seems exceedingly rare that discontinuous steel, or every other bar/wire cut occurs at the actual saw cut location. I also cannot see how not cutting the steel would restrain the crack. When the slab shrinks it puts the slab and the steel in tension. Even with #4 bars @ 16" in a 6" slab, the transform area of steel to concrete is only 1.35 sq in./ft, which is much less than the 1/5 of the slab depth (14.4 sq in./ft) and should effectively weaken the slab to illicit a crack there.
Are these details stopping/cutting the steel just archaic, or is there a concept I have missed? What depth do you use (1/5 is our standard)?