Ultimate resisting capacity of slender RC columns

In this paper, nonlinear analyses of slender RC (reinforced concrete) columns are conducted, and an improved criterion to estimate the load carrying capacity of slender RC columns is proposed. To simulate material nonlinearity including the cracking of concrete, the layer model is adopted, and the initial stress matrix is considered for the simulation of the P–Δ effect. After correlation studies with previous experimental and numerical results to verify the accuracy of the numerical model developed, numerous parametric studies are conducted, and a regression formula that can give a more exact resisting capacity of slender RC columns is proposed on the basis of the numerical results obtained. Finally, the P–M interaction diagrams constructed from the proposed formula are compared with those constructed from a rigorous nonlinear analysis with the objective of establishing the accuracy of the proposed formula. From the results obtained, it is found that the proposed equation is effective in determining an initial section of slender RC columns at the preliminary design stage.