ABSTRACT
This paper deals with the behavior and design of steel profiles, in situations where instabilities (both local and global) play a significant role. A recentlydeveloped new approach, the Overall Interaction Concept (OIC), is presented and detailed. Applicable to the design of both sections and members, it has been developed mainly to i) improve actual design practice, ii) increase accuracy, and iii) advance simplicity and consistency. The proposed approach relies on the generalization of the relative slenderness concept, and on establishing this parameter as the key to rule the resistance-instability interaction:
RRESIST represents the factor by which the actual loading has to be multiplied to reach the pure resistance limit, while RSTAB is the factor used to reach the buckling load of the ideal member (instability limit). Once determined, this λrel value is further used in the design procedure to get into a so-called “interaction curve” and leads to the determination of a “χ” value (see Figure 1), which represents the penalty due to instability effects on the “pure resistant behavior.
