Simplified calculation model for load-bearing cold-formed steel composite walls under fire conditions

Abstract

The conventional simplified model only restricts the bending buckling around the minor axis and overall torsional buckling, which is not suitable for external sandwiched cold-formed steel composite walls. Moreover, a solution to stud–track connections must be achieved in establishing the overall structure model. In this article, a simplified calculation model is proposed to accurately and efficiently reveal the fire performance of cold-formed steel composite walls. A tension spring is adopted to simulate the boundary condition that limits the axial thermal expansion of the studs at elevated temperature. Meanwhile, the simplified applications of the panel constraints and stud–track connections are also given in details. Finite element analysis using the developed simplified calculation model is conducted to simulate five full-scale cold-formed steel composite walls with different configurations. Comparisons between the finite element analysis and fire test results show an overall agreement on the failure modes, cold flange temperatures and lateral deflections at mid-height of the studs. These results demonstrate that the developed simplified calculation model is able to simulate the fire performance and predict the lateral deflection of the external sandwiched cold-formed steel composite walls accurately. Finally, the key factors affecting the lateral deflection of the studs are analysed.