BC for open-coiled spring

Hello to all,
Asking for help with practical advice on simulation OPEN-COILED HELICAL SPRING WITH LARGE DEFLECTION (springs with ends fixed against rotation):
Imagine a very long spring which is fixed at one end, and the axial force (or displacement) is applied to another end. As is known, in such case the coils must be radially compressed. I'm guessing, that in the middle turns of springs deformation will distributed evenly (axial deflection and radial compression in each turn). How to make the boundary conditions in FE model (in Abaqus) at the ends of such piece of spring (up to ten turns) to simulate a uniform deformation?
Regards,
Mike