A refined numerical approach for the ultimate-load analysis of 3-D steel rod structures

As far as steel-rod structures are concerned the yield-hinge theory is a very efficient approach of the ultimate-load theory. Unfortunately, most of the published strategies suffer from considerable deficiencies which depend on two main reasons: first, the yield condition is not approximated very well, and, second, a flow rule is not incorporated at all. This may significantly affect the calculated load-carrying behaviour and as a consequence the elasto-plastic failure prediction. In the present paper a consistent formulation of a refined numerical method based on the yield-hinge theory is consistently developed from the theory of plasticity. The derivation is carried out in the framework of a geometrically nonlinear Timoshenko beam theory discretized for the displacement based finite element method. The plastic deformations can be interpreted as three-dimensional eccentric yield-hinges (generalized yield-hinges). The presented numerical xamples show the efficiency of the proposed method.