A Robust Computational Method for Ultimate Strength Analysis of Arbitrary Reinforced Concrete and Composite Sections Subjected to Axial Force and Biaxial Bending

Abstract

This work proposes a robust method for the computation of the ultimate strength of reinforced concrete and composite sections of arbitrary polygonal shapes subjected to axial force and biaxial bending. In this method, universal constitutive relationships are allowed for all section materials, including unconfined and confined concrete, reinforcements, structural steel, and other composite materials. Mathematical equations are presented to calculate the section's internal forces; therefore, no numerical integration needs to be performed in the calculation of the internal forces of the concrete sections. In addition, a transfer function is constructed that allows a searching of the depth of the neutral axis to be performed over an infinite interval by the bisection search method. This method can be conveniently coded into a computer program. Several numerical examples were implemented and the results were compared with those given by the classic fiber method. It shows that the proposed method presents efficient computation, stable converge, and accurate results.