If you look closely at the connection, it is made of multiple rebar welded together to completely fill the gap and then welded to both panels. There is no room for any movement whatsoever. That's the mistake.
The way to do it, if it needs to be done, and I do see your point here Hokie, is to limit the gap to 5/8" to 3/4", and fill the gap with a single #4 bar 6" long, welding the bar 2" on one side at one end, and 2" on the other side at the other end. That way there is space for expansion and contraction. I have also seen the same thing done with bent angles, but I have also seen more cracking with that one due to the increased rigidity of the angle.
Mike McCann
MMC Engineering
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