A model for the strength analysis of high-strength concrete (HSC) columns subjected to eccentric loading is proposed. The model is based on a stability analysis of pin-ended columns using the theoretical sinusoidal equation for the deflected shape of the column. The reduction in column stiffness as the axial load increases, representing the basic characteristic of the inelastic response of columns, is considered subject to equilibrium conditions, compatibility requirements, and constitutive relationships for the concrete and reinforcement. The tension-stiffening effect was taken into consideration. The column integrity is limited by either the material or the instability mode of failure.
The method was applied to a wide range of experimental data and was compared with the Egyptian, European, and American building codes of practice. The ultimate strength predicted by the proposed model showed excellent agreement with the test results and was in good agreement with the codes of practice. The mean predicted-to-experimental ultimate load ratio was 0·94, with a coefficient of variation of 10·8%.