Fire performance of superabsorbent polymers protected full-scale cold-formed steel wall lined with plasterboards

Superabsorbent polymers (SAPs) have shown promise in enhancing the fire resistance of steel structures because of their exceptional absorbency and water retention capabilities. This study innovatively applies SAP insulation to cold-formed steel (CFS) walls with gypsum (GP) boards to improve fire performance. One full-scale CFS wall underwent axial compression testing at ambient temperature, and four full-scale fire experiments were conducted on CFS walls with load ratios of 0.27 and 0.85. All specimens were sheathed with double layers of GP boards, and rock wool served as the cavity insulation, with SAP insulation material applied to the cavity of wall studs. Additionally, a novel finite element model was developed to simulate the fluid-heat interaction within a furnace-CFS wall. The simulation results showed that SAP insulation material significantly changes the fireinduced failure mode in wall studs at a 0.27 load ratio, transitioning from hot flange (HF) local buckling to local buckling of the whole stud section. The inclusion of SAP insulation material absorbs heat, effectively delaying the rise in wall stud temperature. This property significantly enhances the structural performance of CFS walls during fire exposure. With SAP insulation material, the fire resistance time of the CFS walls increased by over 66 min compared to non-SAP insulation material counterparts. Moreover, increasing the stud web depth and reducing the HF width-to-thickness ratio can enhance the fire performance of CFS walls. The HF critical failure temperature of specimen S2 with an HF width-to-thickness ratio of 80 was 783 degrees C, 150 degrees C higher than that of specimen P2 with an HF width-to-thickness ratio of 67. Additionally, the adverse effect of screws on the fire performance of the CFS wall was localized. After 120 min of fire exposure, the temperature on the ambient side, which was severely influenced by the screws, was 360 to 370 degrees C.