Will,
I haven't sorted out how to express a formula in a simple HTML format, so here's an attempt at it all on a single line:
Force = (3 times the load)divided by (2 x (tenon width x tenon depth)), then multiplied by ((joist depth/tenon depth)squared)
If you have a copy of the TFG book, it's on page 72, midway down the right column.
The reason for joists that are deeper than the carrying sill is because they extend over a 14' span in the forebay. (The sill is supported by the foundation at one end, and is atop posts at the outer end of the forebay.) I'd submit a drawing, but the darned electrons are all frozen up here tonight and my internet connection is about as slow-flowing as the beet juice in my tractor tires
(okay, maybe it's me that moving slow . . . )
