Publication
The seismic performance of Eccentrically Braced Frames (EBFs) relies on the inelastic behavior of the respective steel link. Depending on their geometric characteristics, EBF links are categorized as short, intermediate, and long. These should respect performance criteria depending on their stiffener spacing requirements that have been established in accordance with prior physical tests conducted in the early 1980s. This paper summarizes the stiffener spacing requirements in accordance with AISC 341-22 and Eurocode 8 in conjunction with findings from pertinent experiments on EBF links, which have been collected from prior literature. The stress state of the EBF web panels can result in web instabilities. Therefore, idealizing the web panel as a plate enables the formulation of a plate buckling problem that is then solved analytically via the deformation theory of plasticity. The solution of the plate buckling problem allows for the development of new stiffener spacing requirements for short and intermediate length links. The proposed requirements, which are validated by continuum finite element simulations of representative EBF link geometries, generally lead to either more economic or safer design solutions relative to the current design status quo. Particularly, it is found that the number of stiffeners needed to satisfy the current seismic design requirements according to the North American and European seismic provisions for short links may be relaxed by 35%, on average. With regards to intermediate links, it is found that the proposed stiffener requirements satisfy the established performance objectives while the current stiffener spacing requirements do not at many instances.