Thermal and mechanical modeling of load-bearing cold-formed steel wall systems in fire

Although a few fire experiments have been carried out on load-bearing cold-formed steel (CFS) wall systems, the understanding of their fire performance is still limited, and further parametric analysis on the basis of such experiments is expensive and time-consuming. This paper presents a simplified numerical approach to predicting the thermal and mechanical responses of CFS wall systems in fire. Thermal physical property experiments were carried out to measure the essential material properties. With those material properties as inputs, a one-dimensional thermal response model was developed to predict the heat transfer across the cross section of CFS wall systems. Both heat convection and radiation were considered in the thermal boundary conditions. The governing equation was expressed in the form of implicit finite-differential equations and solved using the Gauss-Seidel method. The model predictions of temperature responses of CFS wall systems were in good agreement with the measured temperature responses in the fire experiments and also compared well with the modeling results in literature with improved efficiency and convergence in computation. In addition, a thermomechanical response model was developed to predict the time-dependent lateral deflection and fire resistance time for CFS wall systems in fire and was validated by the experimental results in literature. All these studies provide an efficient approach for the fire performance analysis of load-bearing CFS wall systems.