Steel column stability and implications in the seismic assessment of steel structures according to Eurocode 8 Part 3

Seismic performance assessment of new and existing steel structures based on nonlinear static (pushover) analysis necessitates the use of engineering‐oriented models that trace the nonlinear response of structural steel elements under static and cyclic loading. Recent experiments and corroborating finite element simulations on I‐ and H‐shaped steel columns constitute an important data source for such a development. This paper presents important insights regarding the behaviour of steel columns under cyclic and monotonic loading based on an assembled steel column database. We propose simple, yet accurate, practice‐oriented models to predict the strength and deformation capacities at yield and ultimate rotation (near collapse) of steel columns within the framework of Eurocode 8 Part 3 (EC8‐Part 3). The proposed models are derived from first principles of mechanics along with robust statistical approaches leveraging the assembled datasets. It is shown that modelling provisions for steel columns in the current EC8 Part 3 do not reflect column behavioural trends from the available databases. The influence of loading history on the derived modelling recommendations for columns is also quantified and discussed. The proposed recommendations may be incorporated in future versions of EC8‐Part 3 for seismic performance assessment of new and existing steel structures.