A complete assessment of the moment-curvature relationship of compressed steel-concrete composite cross-sections

Abstract

In the non-linear evaluation of the behavior of steel, concrete and steel-concrete composite cross-sections, increment and iteration strategies are necessary for the complete construction of the moment-curvature relationship (M-Φ). For the correct simulation of sections composed of strain-softening materials, a numerical strategy based on constant force increments does not capture the downward branch of the M-Φ relationship. Therefore, the present study aims to couple the strain compatibility method to the path-following strategies to go beyond the critical bending moment points in the construction of the relations that describe the complete cross-section mechanical behavior. In this context, the generalized displacement technique, which depends on a generalized stiffness parameter, and the minimum residual displacement method, are adapted to the cross-sectional non-linear problem. To validate the proposed numerical formulation, the results obtained here are compared with the numerical data available in the literature. Additionally, the softening effect on the concrete was increased to induce descending stretches in the moment-curvature relationship, and this condition was correctly evaluated.