Equivalent fire resistance of composite slab made with lightweight concrete

This study examines the fire behaviour of composite slabs made with lightweight concrete, following the fire insulation criteria "I" outlined in Eurocode 4 (CEN 2005). The parametric analysis includes the effect of the airgap, moisture content, thermal properties of the lightweight concrete, and geometrical aspects. Fire resistance time is calculated using two methods - the analytical method from Appendix D of Eurocode 4 (CEN 2005) and a numerical method (ANSYS n.d.). Finite element analysis shows that the moisture content of lightweight concrete significantly impacts fire resistance time. When the moisture content exceeds 3%, the Eurocode method predicts a lower fire resistance time compared to the simulation method. The prediction models indicate that, to achieve the same fire resistance time, a normal-weight concrete section must be 7% thicker than a lightweight concrete section.