Steel Cable non-linear analysis

I'm not really sure how'd you define them. In Eulerian or Timoshenko beam theory, the shear stress (VQ/It) arises because it is assumed that "layers" of the beam cannot slip relative to each other, but this is not entirely the case with a steel cable. If you compared the stiffness of several layers of plywood that are not glued together against the same number of layers of the same plywood that are glued together, the glued plywood will be stiffer because the glued interface allows the transfer of shear loads. In fact, the more I think about it, the more I think that a beam model would be a poor choice.

You might get a more realistic model of a cable by using a discrete number of mass and spring elements, but it'd be rather time consuming to do (I'm not sure if SW can do it either, but I'm not an expert with it so I'll let someone else answer that).

If you don't mind me asking, why are you trying to simulate this? As I said before, this is an easy hand calculation to do; using the FEM to do this is overkill (and will potentially give you very inaccurate results if you don't model it correctly).

are you saying that your question is "how do i add pretension" before you apply your load?

the analysis as you described it is pretty straight forward, fix both ends of the wire, add your point load, run

if you need to pretension, you'll need to use nonlinear to add the pretension first.

then measuring "tension" will be based on the stresses in the wire