I feel like I'm missing something here. I've always understood that braces are ALWAYS compression members. Preferably used in pairs, depending on the direction of force, one is doing the work (compression) and the other is on holiday. As has been mentioned often in this forum, it is not at all uncommon to see peg-less braces in old barns and other traditional frames.
EHC- You state that in your 3-post example, the lateral load would put two braces in tension and do nothing to the other two. I would argue that the load would do something to the other two- compress them! Eliminate the pegs to eliminate tension. The 3-post bent should be designed so that the compression of two of the braces is adequate for the lateral load from one direction and the other two are there for load from the opposite direction. This just takes advantage of wood's property of being stronger in compression than in tension.
A great example is a multiple queen post truss covered bridge. The braces/struts are all in compression, that is they run diagonally from the top of each post to the bottom of the next going toward the abutments so the two in the middle form an inverted 'V'. If you look at a steel truss you usually see the opposite since steel (for the sake of this discussion, let's assume flat stock, riveted or welded) performs better in tension than compression.
I'm curious to see exactly why braces in tension are required. I don't want to assume too much and I hope I'm not stepping on any toes!
Cheers
