Improved refined plastic-hinge analysis accounting for lateral torsional buckling

In this paper, a refined plastic-hinge analysis is improved to account for the effect of lateral torsional buckling. This analysis accounts for material and geometric nonlinearities of the structural system and its component members. Moreover, the problem associated with conventional refined plastic-hinge analyses in that no consideration is given to the degradation of the flexural strength caused by the 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 the lateral torsional buckling. The proposed analysis is verified by the comparison of the plastic-zone and LRFD results. Case studies show that lateral torsional buckling is a very crucial element to be considered in refined plastic hinge analysis. The proposed analysis is shown to be an efficient, reliable tool ready to be implemented into design practice. (C) 2002 Elsevier Science Ltd. All rights reserved.