This paper discusses the convergence and accuracy of the three mixed formulations in the companion paper for a new composite frame element that is suitable for the large-scale, large-displacement inelastic analysis of structures. The convergence is assessed with the inelastic response of a steel-concrete composite substructure under uniaxial loading. The accuracy of the formulations is assessed by correlating the numerical results with experimental data from a steel-concrete composite substructure under uniaxial loading and from the biaxial response of two reinforced concrete (RC) cantilever columns. The correlation studies confirm the accuracy and numerical robustness of the mixed formulations for global response measures such as the force-displacement relation and for local response measures such as the strain and relative slip distributions in the composite member. Special emphasis in the numerical studies is placed on the challenging cyclic, biaxial response of the RC cantilever columns that previous models are unable to capture. The paper concludes with an evaluation of the significance of the bond-slip interaction in RC and composite elements on the local and global response of structural members.