Flexural-torsional buckling and design recommendations of axially loaded concrete-infilled double steel corrugated-plate walls with T-section

This paper investigates the flexural-torsional buckling behaviour about the symmetric axis of axially loaded concrete-infilled double steel corrugated-plate walls with T-section (T-CDSCWs). The T-CDSCW is composed of steel corrugated-plates, infilled concrete and intermediate bolts, among which a positive composite effect further improves load-bearing capacities effectively and thus reduces the thickness of composite walls. The failure mode of the T-CDSCW with high height and small thickness is governed by global instability, and flexural and flexural-torsional buckling may occur for the T-CDSCW under axial compression. This paper focuses on numerical and theoretical analyses of the flexural-torsional buckling behaviour. Based on the refined finite element (FE) model validated by previous experimental researches, parameter analysis is carried out to investigate the elastic and inelastic flexural-torsional buckling behaviour. The formulas of the elastic flexural-torsional buckling load are derived and prove it feasible to design flexural-torsional buckling in accordance with torsional buckling. Numerical results show that the strength reduction factor of flexural-torsional instability can be delineated well by the height-to-thickness ratio of the web and the normalized torsional slenderness ratio of the T-CDSCW. Together with the design formulas of flexural instability, the design formulas of flexural-torsional instability proposed in this paper supplements the design method of axially loaded T-CDSCWs, and provides the foundation for further investigation into global instability of T-CDSCWs under combined compression and bending.