We consider numerical approximations of a class of abstract nonlinear evolu
tionary systems arising in the study of quasi-static frictional contact pro
blems for elastic-viscoplastic materials. Both semidiscrete and fully discr
ete schemes are analyzed. Strong convergence of both approximations is esta
blished under minimal solution regularity. The results are applied to two p
articular frictional contact problems for viscoplastic bodies, where the fi
nite element method is employed to discretize the spatial domain. Under add
itional regularity assumptions on the exact solution, some error estimates
are derived.