Nonlinear behavior of slender RC columns. (1). Numerical formulation

This paper introduces an analytical model which can simulate the nonlinear behavior of slender reinforced concrete (RC) columns. The layer approach is adopted to determine the equilibrium conditions in a section and to consider the different material properties across the sectional depth effectively. The material nonlinearity including the cracking of concrete is taken into consideration, and geometric nonlinearity due to the P-Δ effect is taken into account by using the initial stress matrix. In advance, the creep deformation of concrete is described in accordance with a first-order algorithm based on the expansion of a degenerate kernel of the compliance function. To verify the analytical results, correlation studies with previous numerical results and experimental data are conducted, and numerous parameter studies are followed to discuss the structural responses of slender RC columns according to the changes in design variables. Finally, the necessity for a rigorous nonlinear analysis is emphasized for more accurate prediction of the ultimate resisting capacity of slender RC columns.