Thanks to The Usual Suspects AKA Mark and BAKE!
OK, this makes sense, now. Originally I was concerned about the decrease in beam strength due to the pockets for the joists/summers. I have 4x6 joists in 4x5 by 2" deep pockets in 8x8 beams in this 'barn' floor because I needed to engineer it to handle up to 6000 lb vehicles. I was concerned about the strength reduction of two aligned 2" deep pockets in an 8" beam. I wanted to use the wedges as I had read about, to take out the space so the beam strength was largely retained.
Now I have a somewhat different situation. I realized that with uniform 8 foot spacing of the 8x8 beams and their concrete/steel supports there was no need to orient all the joists the same way and have aligned opposite pockets. So I changed that so the joists run alternating directions, and the flooring is in an 8 foot checkerboard pattern. Looks cool. I think. So the most any 8by8 8 foot beam section has is one side row of 3 pockets 2" deep by 4" wide by 5" high (the 4x6 joists have a 1" curve-in on the bottom)..
SO.. the wedging is less important, but I'd still like to understand how it can be used effectively. I will monitor the shrinkage the next 2 or 3 years to see if I get open there. It's not a cosmetic issue, and the joists should bear weight well, especially as the safety factor I used in Hemlock goes from 5:1 wet to 8:1 after it is dry.
I'm terminology-poor here. Whaza "Oly Screw" and where do they come from? I've heard of them used in Log construction, maybe? I'm thinking that I might put a lag screw into the end of the center joist in each section. Although I somehow don't think a well-joined 8x8 that's 8 feet long is likely to 'spread' much. I'll have a different feeling about the second-floor joints, I think.
Thanks for responding; I keep on learning stuff from other peoples experiences, which is good!
