Coupled thermo-mechanical simulation for the performance-based fire design of CFS drywall systems

In the present study, a fully coupled thermo-mechanical simulation methodology is presented, capable of estimating the response of cold-formed steel drywall systems exposed to fire and evaluating whether or not compliance with the performance-based fire safety requirements is achieved, in terms of the load-bearing capacity (R), integrity (E) and insulation (I) criteria. The proposed nonlinear coupled thermo-mechanical approach, accounting for geometry, material and contact nonlinearities, is validated against full-scale furnace test results of typical, commercially available, load-bearing drywall systems, achieving a very good qualitative and quantitative agreement; maximum discrepancies between the predicted and measured fire-resistance ratings do not exceed 2%. Several parametric studies are carried out, concerning the magnitude of the imposed load on the bearing walls and the effect of the cavity insulation placement on the overall fire performance of drywall systems. It is found that installation of thermal insulation inside the drywall cavity may decrease the system's fire-resistance rating, depending on the employed configuration. The proposed numerical approach can be effectively used to estimate the fire-resistance rating of load-bearing lightweight steel drywall systems in support of performance-based fire design standards.