Nonlinear analysis of space steel frames using fiber plastic hinge concept

A fiber plastic hinge concept in which the cross-section is partitioned into fibers is applied in this research to predict the second-order inelastic behavior of space steel frames instead of the common plastic hinge concept using a specific yield surface. The plastification of the hinge is considered by tracking the uniaxial stress–strain relationship of each fiber on the cross-section during the analysis process. The stability functions obtained from the closed-form solution of a beam–column subjected to end forces are used to capture the second-order effects to minimize modeling and solution time. Using only one element per member in structure modeling, the nonlinear responses predicted by the proposed approach compare well with those given by the ABAQUS program using shell element and plastic zone analyses. Some numerical examples are shown to verify the accuracy and computing efficiency of the proposed approach.