Buckling resistance of longitudinally stiffened plates: Eurocode-based design for column-like and interactive behavior of plates with closed-section stiffeners

Buckling resistance of longitudinally stiffened plates subjected to compression is a crucial issue in the design of many steel bridges. The design methodology of the current Eurocode describes the behavior as a combination of column-like and plate-like behavior. Previous studies well explored the plate-like behavior of compressed stiffened plates with closed longitudinal stiffeners, leading to the conclusions that the critical stress calculation is sensitive to the details of the numerical model, and that in certain situations the Winter-curve is unconservative to calculate the reduction factor for plate-like buckling of stiffened plates. One of the goals of the research presented in this paper is to study the pure column-like behavior similarly. Recent results also suggest that the handling of the interactive behavior in the current Eurocode is sometimes too conservative, and could be improved. The systematic analysis of the interactive behavior is another main goal of the reported research program, focusing on the compression resistance of stiffened plates with closed-section longitudinal stiffeners. To achieve the goals, numerical studies have been conducted by using the shell finite element method. A large number of cases have been investigated, by performing linear buckling analyses to calculate critical stresses, as well as geometrically and materially nonlinear analyses with imperfections, to calculate the resistances. The systematic evaluation of the results finally has yielded an enhanced interpolation between the column-like and plate-like behavior modes, leading to more accurate design resistances.