A numerical method to design reinforced concrete sections subjected to axial forces and biaxial bending based on ultimate strain limits

A new iterative algorithm to design the steel reinforcement of concrete sections subjected to axial forces and biaxial bending is presented in this paper. The algorithm allows for the extrapolation of the ultimate strain limits, traditionally implemented in uniaxial bending theory, to biaxial bending cases. The new algorithm iterates a system of equations presenting high efficiency and becoming useful for any arbitrary-shaped cross section, including multicellular hollow sections. The new approach is compared with experimental results, obtaining good agreement.