ANSYS_How to make couplings as the picture?

Hello everyone,

I am a new user for ANSYS. I am trying to simulate the modal analysis of the section of pipe by ANSYS Mechanical APDL 14.5.

But I got the problem about ... How to make the couplings as the attached picture? 

I need to set the same condition of each pair of node on the right (nR) and the left (nL).

Thank you very much

Yours sincerely,

Adisorn P.