The Influence of Eccentricity on the Behaviour of Thin‐Walled Cold‐Formed Steel Members with Open Cross‐Sections under Compression

Thin‐walled cold‐formed steel elements represent an attractive structural solution due to the fast manufacturing and erection time on site. Their small thickness leads to imperfection and eccentricities sensitivities. An experimental program was performed on short members with lipped channel cross‐section of 150×60×20×2 mm, subjected to (1) eccentric compression about the minor axis, in a range of eccentricities between −40 mm and +40 mm and (2) eccentric compression about the major axis, in a range of eccentricities between 0 mm and +90 mm. Shortening of all specimens was measured in two ways, i.e. (1) using the displacement gauge integrated with the machine crosshead beam and (2) from deformation fields obtained using Digital Image Correlation system (DIC). The quantitative results, presented as ultimate loads vs eccentricity curve, emphasize the influence of the eccentric load on the capacity of the element and on the type of plastic mechanism formation. Finite element analyses were performed to simulate the behaviour of short members in eccentric compression using the commercial FE software ABAQUS/CAE. Static non‐linear analyses were carried out in displacement control. Both geometrical and material non‐linearities were included. The experimental results confirm two different basic failure mechanisms depending on the load eccentricity direction applied to the studied members with open cross‐section.