Simulating Interactive Buckling in Steel Members Using a Torsional Fiber Element Integrated with a Multiaxial Local Buckling Constitutive Model

Interactions between local, flexural, and lateral torsional buckling often compromise the stability of structural steel members. An approach that integrates a displacement-based fiber element capable of simulating torsion warping as well as flexural and lateral buckling, and a multiaxial constitutive model that represents local buckling in an effective sense is presented. This integrated approach, termed the torsion fiber element–plate local buckling (TFE-PLB) approach, includes features required to simulate various types of buckling, i.e., local, flexural, and lateral torsional, and the interactions between them in wide-flanged steel members. The approach, developed for monotonic loading, is implemented in an open-source platform and is accompanied by calibration procedures of its parameters and best practices for its use. The implemented and calibrated approach is used to predict the response of 58 beam-column configurations that interrogate a range of geometric and loading parameters. The benchmark response is established through continuum finite-element simulations. Comparisons between the TFE-PLB and the continuum finite-element simulations indicate that the TFE-PLB approach can simulate the important aspects of interactive buckling, both in the sense of overall load–deformation response as well as local deformation fields. The TFE-PLB models require only 1/10th the computational time as compared to the continuum finite-element models. Limitations of the TFE-PLB approach are summarized, along with directions for future improvements.