Effective Modulus Method (EMM) concept applied to thin‐walled steel columns.

The design of thin‐walled steel members, subjected to compressive stresses, requires complex analysis to account the interaction between local, distortional and global instabilities. There are simplified methodologies that allow simulating the effects of local and distortional post‐buckling behavior in usual structural members. The Effective Width Method (EWM) performs this simulation by changing the geometry of the cross‐section, being the pioneer methodology for the analysis of thin‐walled members. The Direct Strength Method (DSM) allows the determination of resistant forces through simple‐to‐use formulas, eliminating the calculation of the geometric properties of the section as required by the EWM. This paper presents the Effective Modulus Method (EMM) concept, which simulates the effects of local and distortional post‐buckling, to establish simplified design methodologies, desirably leading to more rigorous results than those provided by the available methodologies. In this approach, local and distortional post‐buckling effects are simulated by changing the mechanical characteristics (namely the modulus of elasticity) of the cross‐section of the members. Specifically, the article presents (i) the proposal of the new design methodology and (ii) the comparison with experimental and numerical results obtained by finite element shell models.