Most nonlinear analyzers like ACTION and PLANS do not account for cross-sectional flexibility of thin-walled frame members. They do however, permit simulation of plastic hinges. Judging by the excellent correlation between theory and experiment, such analyzers appear quite adequate in predicting reasonably accurately gross response parameters of thin-walled frame structures even though they may undergo severe cross-sectional deformations. ?? 1979.
Kamat, M. P. (1979). On the importance of cross-sectional flexibility on gross response. Computers and Structures, 10(5), 831–832. https://doi.org/10.1016/0045-7949(79)90048-8