Sensitivity analysis of steel moment frames accounting for geometric and material nonlinearity

A procedure for sensitivity analysis of planar steel moment frameworks accounting for second-order displacement effects and inelastic material behavior under combined bending moment and axial force is presented in the context of performance-based design for seismic loading. Analytical formulations defining the sensitivity of nodal displacements to modifications in member cross-section sizes are derived. A nine-story moment frame example illustrates the applicability and accuracy of the developed formulations.