3-D second-order plastic-hinge analysis accounting for lateral torsional buckling

In this paper, 3-D second-order plastic-hinge analysis accounting for lateral torsional buckling is developed. This analysis accounts for material and geometric nonlinearities of the structural system and its component members. Moreover, the problem associated with conventional second-order plastic-hinge analyses, which do not consider the degradation of the flexural strength caused by lateral torsional buckling, is overcome. Efficient ways of assessing steel frame behavior including gradual yielding associated with residual stresses and flexure, second-order effect, and geometric imperfections are presented. In this study, a model consisting of the unbraced length and cross-section shape is used to account for lateral torsional buckling. The proposed analysis is verified by the comparison of the other analyses and load and resistance factor design results. A case study shows that lateral torsional buckling is a very crucial element to be considered in second-order plastic-hinge analysis. The proposed analysis is shown to be an efficient, reliable tool ready to be implemented into design practice.