Analytical investigation of vehicle fires in precast concrete parking structures

Research was performed to investigate the effects of vehicle fires in precast concrete parking structures. A typical precast concrete parking structure was analyzed for a series of vehicle fires, and the resulting fire loads (temperature and heat flux histories) at various locations in the structure were determined. Analysis parameters were systematically varied to explore a range of structure geometry and fire parameters (single-versus multivehicle fires). Analysis was performed using a computational fluid dynamics computer model. Heat flux histories obtained from the fluid dynamics computer model were used as input to subsequent finite element analyses to determine the temperature rise in the prestressing strand of the double-tee floor members. The increased prestressing steel temperatures were then used to estimate the reductions in steel strength. Results show that the geometry of the structure has a significant effect on heat transmission. For the nine fire scenarios considered, vehicle fires caused only minor reductions (maximum of 15%) in the strength of the prestressing steel of the double-tee floor members.