Abstract: Flexibility-based and stiffness-based fiber model beam-column elements for the second order analysis are investigated in this paper. Several typical examples with experimental data are selected for computational effectiveness comparison between the two methods. The validity of flexibility-based beam-column elements is also examined for the second order analysis of space member structures. The results show that flexibility-based beam-column elements are apparently superior to stiffness-based beam-column elements in dealing with instability problems of structures and the flexibility-based beam-column element is presently one of the most practical and efficient element models handling material and geometrically nonlinear problems of framed structures.