Calculating deflection of a tensile structure

Hi, I have been trying to find the deflection value for my structure.

However, I have few problems I am unable to solve:

1. I use pretension cable to secure the beam. How do we simulate pretension cable? I use pretension load but it doesn't seem to work. I also modify the beam to have bending stiffness.

2. My deflection only makes sense when I add extra supports on the nodes of the cable and the beam. Not very sure whether it can work that way.

Thanks in advance for any help.