An analytical model for the determination of the compressive response of R.C. members having square transverse cross-section and reinforced with steel angels at the corners and steel plates connecting the steel angles is presented. The model is able to consider the contribution in confinement due to transverse and steel angles including buckling phenomena for steel angles was compared with experimental data available and with those obtained by using the other models available in the literature. Finally, a comment on the design prescriptions given by European and National codes in relation with the results here obtained is made.