I am modeling a sheet pile wall using liner elements in FLAC v9.6. Currently, I have assigned an elastic model to these elements, but I would like to know how to specify a plastic moment capacity so that a plastic hinge can form and the corresponding deformation will occur once that capacity is exceeded.
You might need to change the liner elastic constitutive model to an elastoplastic one, e,g, V-M model.
An example how to set elastoplastic models for structure: