How can a zero length torsional spring element be modeled in ANSYS?

Aoa

Hello
brothers

Currently,
I‘m working on the determination of the mechanical properties of carbon nanotubes
for different loading cases using ANSYS software ( i need to use them in my
model). My Finite Element model of graphene and carbon nanotube is working fine with beam188 element, but I have
some technical problems in my simulation. These problem are summarized in
points as follow;

•  I want to replace the beam element by two springs (linear torsional spring and nonlinear
  stretching spring element), as shown below. Each spring will produce one type
  of deformation in the nanotube. The problem is with the torsional spring that
  must be modeled as a zero length element. So, which element can be used in this
  case and it can provide a properties for zero length element?

• If there is an element that can be used as it described above, can anyone one help
  me to understand the theory  of the element?

Thank you

Moosa  S.M. Al Kharusi