Flexural rigidity EI of RC slender columns under axial force and biaxial bending of rectangular section for the moment magnifier method

Abstract

In this paper, an expression is proposed for flexural rigidity EI of RC slender columns under instantaneous and sustained axial force and biaxial bending with rectangular cross ? section, symmetrically reinforced in both axis. This expression is valid not only for normal strength concrete but for high strength concrete. Nevertheless, the effective length in the both principal directions of bending must be similar. The results have been check against 108 experimental tests taken from the literature. The proposed allows verification and design of slender columns with enough accuracy for the professional practice. This method is applicable to an important percentage of columns in building.