Local buckling and design of aluminum I-shapes

Current standards use simplified approaches to predict the resistance of aluminum elements that are not optimized to account for the effects of strain hardening, instabilities, and heat reduced properties. This paper summarizes investigations towards the development of an alternative design method for aluminum open cross-sections, based on the Overall Interaction Concept (O.I.C.). This innovative design approach relies on the interaction between resistance and stability, and also allows to consider geometrical and material imperfections. Moreover, it allows to obtain direct, precise and consistent resistance predictions using continuous buckling curves. A numerical finite element model was developed to accurately predict the cross-sectional resistance of aluminum elements. Its efficiency was validated by comparing its numerical resistance predictions to available experimental test data. Extensive parametric studies were then conducted, allowing to study the impact of varying geometries, alloys, and load cases on the resistance. Using the results from more than 2 300+ numerical simulations, O.I.C.-type design proposals were formulated for the local resistance of extruded and welded aluminum sections. The performance of the design proposals was evaluated by comparing their resistance estimates to the reference numerical results and to resistance predictions from the Canadian, European, and American aluminum design standards. The comparisons showed that the O.I.C. design proposal leads to much more accurate and consistent results than these standards, while remaining simpler and more efficient.

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