Robustness of square hollow column sections in open-sided corner-supported modular steel buildings

This paper investigates the performance of the commonly used and computationally efficient one-dimensional finite element line elements in capturing the nonlinear buckling response of a hot-finished steel column with global geometric imperfection as well as the bending and axial load response of a welded tubular T-joint connection. Frequently, the robustness assessments of corner-supported modular steel buildings (MSBs) have been based on perfectly straight columns which do not represent the actual profile of the columns due to imperfections in the steel fabrication process. Also, the assumption of fully rigid beam-to-column connections in numerical models with welded tubular joints may not be appropriate due to the flexibility of hollow sections’ wall which is susceptible to local deformation. In the analysis in this paper, a column with the global geometric imperfection of L_eff/1000 modelled using line elements was found to perform similarly to experimental results in terms of capturing global buckling response. For the welded T-joint, a 3D solid element model was investigated to capture the failure behaviours. The assignment of the joint behaviours, obtained from the results of a 3D solid element model, in the spring element connecting the beam and column (line element) reproduces a joint response similar to that in the 3D solid model. The practical application of this study is that a high-fidelity phenomenological model of corner-supported MSBs can be produced for use in the robustness analysis of an entire MSB.