An efficient approach to limiting the elastic range in advanced analysis of steel structures via RPHM

Abstract

Over the years many research on the nonlinear behavior of steel structures has been made. The Refined Plastic Hinge Method (RPHM) is a fast and accurate alternative to simulate, in concentrated form, the plasticity of the structural systems materials. In recent studies, there was a loss of accuracy in the analysis of steel structures under minor axis bending, in the conventional method of RPHM where pseudo‐springs are used at the ends of the elements to simulate the flexural stiffness degradation. In this approach, the pseudo‐springs at the finite elements ends have infinite stiffness in elastic range, with gradual loss of stiffness in elastoplastic stage and a null stiffness in plastic range. For the methodology adjust to this issue, the fictitious springs were replaced by the tangent modulus of elasticity of the material and presented as a viable solution. In this paper, we propose the study of the interaction curves behavior for application in RPHM with pseudo‐springs, considering the bending around major and minor axes of inertia, with a greater focus to RPHM using the tangent Young's modulus. The Strain Compatibility Method (SCM) is used, which through a nonlinear procedure, the moment‐curvature relationship is defined allowing to obtain the exact point where the cross section starts the yield process. Thus, it is possible to trace the initial yield curve realistically minimizing simplifications. The residual stresses models of AISC‐LRFD e ECCS for I sections will be used. The results will be compared with numerical and experimental data available in the literature.