Numerical modelling of lightweight concrete panel lined external LSF walls in fire

The growing shortage of housing worldwide requires the use of advanced construction materials, products and methods. Two such notable products are light gauge steel framing (LSF) and lightweight concrete panels. LSF offers higher structural efficiency and faster construction times, while lightweight concrete panels are non-combustible, addressing the concerns of recent cladding fire accidents. This paper presents the fire resistance level (FRL) predictions for steel-concrete composite wall systems that combine LSF with lightweight concrete panels (autoclave aerated concrete panels) as external cladding. Finite element heat transfer and structural models were developed and validated to predict the temperatures in the walls and their structural failure times when exposed to fire from external side. A numerical parametric study was then conducted with varying panel thickness, cavity insulation and fire exposure (both internal and external). Results show that external LSF walls with 75 mm lightweight concrete panels could achieve FRLs of more than two hours when exposed to external fire for load ratios up to 0.7 due to low thermal conductivity of the panels. FRLs reduced by more than 30% when panel thickness was changed from 75 mm to 50 mm. The use of lightweight concrete panels led to higher cavity and stud temperatures in non-cavity insulated walls when exposed to internal fire, resulting in lower FRLs compared to internal LSF walls.