The Overall Interaction Concept: an Alternative Approach to the Stability and Resistance of Steel Sections and Members

The Overall Interaction Concept (O.I.C.) stands as a new design approach that aims at a straightforward design check of the stability and resistance of steel members. It was developed in response to the expansion of high strength steel products, where instability has more influence and deserves specific attention, especially at the cross-sectional level.
Based on the use of a generalized relative slenderness and so-called interaction curves, it applies to both open and tubular cross-sections, further includes potential non-linear material behavior (beneficial strain hardening effects, e.g. stainless steel or cold formed hollow profiles) and covers combined loading cases. In addition, it can be applied in a similar manner to cross-section or to member verifications.
The present paper first describes the bases and features of the O.I.C.; detailed information is given on its application to either sections or members, to combined loading situations, and to materials exhibiting a high degree of non-linearity. Then, its accuracy and applicability is tested against many experimental results and FE simulations, and the potential for the O.I.C. to become an accurate and effective approach for practical design is demonstrated.
Provided additional complementary developments, the O.I.C. may appear as a powerful alternative to the current design methodologies, and serve as a basis for the next generation of standards and practical tools, especially in the frame of an increasing use of high steel grades.

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