The NLCem3 material is only available through the ATENA-GiD interface (or manual modification of the ATENA Input file .inp), not in the ATENA Engineering 2D, 3D GUEs. However, the NLCem2 material captures the confinement well enough for the vast majority of usual situations. I think I do not need to repeat that 3-dimensional modelling is typically required to capture the confinement effects accurately?

If you have a model with NLCem2 and think the confinement is not well captured in the analysis, please send us your model such that we can check it and possibly give improvement advice (switching to NLCem3 is usually NOT the first thing to do).