So it sounds like kangaroo may be the best path forward. You can represent the joints as small line segments – you probably don’t want then to actually intersect, just be at a constrained distance based on the joint geometry.
I think there is a great discussion of a similar strategy here: https://discourse.mcneel.com/t/reciprocal/73990/13
The examples are not columns, but the challenges+solutions are similar.
Alternatively, you could calculate the # of the framing elements in plan based on the requires chord height of the corresponding arc segment so that chord heigh matches the desired joint width (more framing elements, the shorter the chord height). I will try to find some time to illustrate that…