Energy analysis of the critical force of slender RC columns

Abstract

© ICE Publishing: All rights reserved. A semi-analytical procedure for the determination of the critical force of a pin-ended column loaded by axial force and bending moment is proposed. It is based on the principle of minimum potential energy of internal and external forces. The equations for strain energy have been derived for the first- and the second-order displacements per section, including compressed and tensile concrete and reinforcement. The energy of the external forces with axial and flexural displacement effects has been derived on the assumed sinusoidal deflection curve. The trapezoid rule is applied to integrate the segment internal energy. The proposed method uses a non-linear stress–strain curve for concrete; bilinear elastic–plastic relationship for reinforcement; equilibrium conditions at a sectional level to generate the strain energies along the member. The effects of shear deformations are neglected. The effect of lateral confining by the stirrups to strength is also analysed. The results obtained with the proposed model have been verified and compared with experimental results from the literature.