Optimal Design of Geometrically Nonlinear Steel Structures Using Advanced Analysis

Advanced analysis has been shown to improve material efficiency in statically indeterminate steel-framed structures compared with member-based linear elastic design methods. However, limited research has investigated its applicability to geometrically nonlinear steel structures where residual stresses are induced by the bending process. In this study, the material optimization potential of advanced analysis has been quantified for two arch-based structures by comparing the volume of steel required to satisfy the criteria of both the system and member-based analysis methods in accordance with AS 4100:2020. The two structures were analyzed using the finite element analysis software Strand7 (R3.1.6) and subjected to combined gravity and wind loading in alignment with the serviceability and ultimate limit states specified in AS 1170.0:2002. System behavior was analyzed through the Arc-length plastic zone method. The results indicate that in one of the arch-based structures, advanced analysis can improve material utilization by 8.1%. Provided that future research both validates the use of the reduced stiffness method for treatment of initial geometric imperfections and verifies system reliability factors for structures with curved geometries, advanced analysis presents a practical design method for this structure. Comparison of the two case studies found that advanced analysis has the potential to improve material efficiency only when linear elastic failure is governed by ultimate limit state criteria. It is therefore evident that the material optimization findings of this research cannot be generalized to all arch-based structures, as they are contingent upon the geometry of the model analyzed, the loading scenarios considered, and the deflection limits adopted.