Nonlinear finite element analysis of ductile elasto-plastic structures

Nonlinear finite element modeling techniques as applied specifically to steel special moment resisting frames (SMRF) will be examined to determine the most proficient modeling techniques. The parallel element modeling technique will be introduced as a means to improve the material modeling accuracy and increasing the numerical stability during nonlinear analysis. The difficulties in capturing the hinge formation in steel moment resisting frame can be reduced and the numerical instability involving spontaneous unloading can be eliminated using secondary element with insignificant stiffness. Sample analyses will be included using leading commercial finite element software such as ANSYS and COSMOS/M to illustrate the implementation of the parallel element modeling techniques for nonlinear finite element analysis. The benefits of the proposed modeling technique will be demonstrated for both nonlinear static analysis and nonlinear dynamic analysis.