This paper presents a critical assessment of the ability of existing Drucker-Prager (D-P) type plasticity models to
predict the behaviour of confined concrete using both experimental observations and a recent analytical model.
This assessment shows that for a D-P plasticity model to succeed in predicting the behaviour of FRP-confined
and other passively-confined concrete, it needs to possess the following three features: (a) a yield criterion which
includes the third deviatoric stress invariant, (b) a hardening/softening rule which is dependent on the confining
pressure; and (c) a flow rule which is dependent on both the confining pressure and the rate of confinement
increment. None of the existing D-P type models possesses all three features, so they cannot be expected to lead
to accurate predictions for both actively-confined and passively-confined (e.g. FRP-confined) concrete.