How to manage the model of a truss

Hello, 

I'm working on a optimization of a steel element: I have a truss (traction and compression) rod that connects to the element to be optimized.

My question is how should I consider the axial force on my rod (is a hollow circular section rod)? 

The hub in which the rod is raised is non-deformable, how can I set this element? How can I connect this hub to the element to be optimized so that the forces are transmitted?

How can I match the mesh of the two different components?

Thank you very much

 

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