Improved refined plastic hinge analysis accounting for strain reversal

In this paper, the refined plastic hinge analysis is improved to account for the effect of strain reversal. This analysis will permit sequential loading to be applied to structures as well as consider material and geometric nonlinearities. Moreover, the problem of conventional refined plastic hinge analyses underestimating the strength of structures subjected to sequential loading 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 outlined. The modified stiffness degradation model approximating the effect of strain reversal is discussed in detail. The load displacements predicted by the proposed analysis compare well with those given by a plastic zone analysis, and a case study is provided for an unbraced frame. Member sizes determined by the proposed analysis are compared with those of the conventional refined plastic hinge analysis. In conclusion, the proposed analysis is presented as an efficient, reliable tool ready to be implemented into design practice.