Originally posted by Don P:
Let me try an example.
A 24' kingpost truss with 12/12 pitch, 10000 lb combined load and bottom chord at the plate. I come up with ~3750 lbs tension at the spline and ~5300 lbs compression at the heel joint.
If I raise the bottom chord do the forces increase as a proportion of height the chord is raised up the king? In other words, if the tie moves up 1/4 the height of the king does the tension increase by 25%?
Don, Also consider, the heel joint (rafter on top of tie) is well suited to handling the compression forces. As soom as you begin to move the tie up the truss, the joinery will have to change to a tenon and peg or wedged dovetail in a mortice that has to deal with the forces in tension. Tom
