A refined plastic-hinge-based formulation for advanced analysis of CFST columns: a co-rotational proposition
Palavras-chave:
CFST, lumped plasticity, NM diagram, non-linear analysis, pseudo-springsResumo
The present work aims to propose a lumped plasticity-based numerical formulation for the non-linear
analysis of concrete-filled steel tubular (CFST) columns. The study is divided into two main parts: cross-sectional
analysis and global structural analysis. The local analysis is made by means of the strain compatibility method.
Thus, the moment-curvature relationship is evaluated by an incremental-iterative process. Through of this method-
ology, the limits of uncracked, cracked, elastic, inelastic and bearing capacity are determined for various axial
efforts. Thus, the NM diagram is calculated with three curves and five regimes to describe the cross-section flex-
ural stiffness. For the precise evaluation of this numerical procedure, the materials constitutive relationships are
explicitly considered. For the global analysis, the co-rotational-based approach is used to describe the finite ele-
ment formulation allowing large displacements and rotations in the numerical model. This approach is coupled to
rotational pseudo-springs at the ends of the finite element, where the gradual loss of stiffness was determined by
combining the normal force and bending moment (NM) in the cross-section. The numerical results were compared
with experimental results [15]. In average, the results found present an error of 0.1% in relation to the data obtained
in the laboratory, demonstrating the accuracy of the proposed numerical formulation.
