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

Abstract

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.

Failure mechanisms of TWCFS members considering various eccentricities

“…Details about the deformation obtained and the development of the local plastic mechanism from both the experiment and the analysis of finite elements obtained for the SP2 samples are presented in Fig. 11 [5,7]. For SP1 specimens, similar deformation patterns were observed.…”

“…without any inconsistency in the stress map. The tensile tests revealed a similar curve for both the flange and the web of the specimens, so the mean values were used for the entire cross section, without considering the effect of residual stresses [7]. Both geometrical and material nonlinearities were included.…”

“…Fig. 9 presents the maximum load for each eccentricity for both experimental and numerical results (using ABAQUS), the associated failure modes and the transition from distortion to local failure with variation of eccentricity for specimens SP2 [5,7]. The corresponding dia grams for the SP1 specimen are shown in Fig.…”

“…Fig.14Deformed shape of the specimen tested under eccentric compression about the major axis -set SP4[5,7] …”