Experimental Study on the Fire Characteristics of Double-Unit Rack Systems in Logistics Facilities

Although rack systems in logistics facilities provide high storage efficiency, they are inherently vulnerable to heat transfer and fire spread during fire incidents. Despite extensive research into rack fire behavior, most studies relied on numerical analyses because of the diversity of rack configurations and high cost of full-scale fire experiments. Consequently, there has been a lack of experimental data for validation. In this study, a full-scale fire experiment was conducted on a widely used double-unit rack, and key fire characteristics such as heat release rate (HRR) and heat flux were measured. The results confirmed that peak fire conditions were reached at ~520 s, with a maximum HRR of 14 MW, maximum heat flux of 124 kW/m<sup>2</sup>, and fire load of 914 MJ. These values significantly exceeded those of ordinary combustible materials. Such severe fire characteristics pose a considerable threat to the structural fire safety of logistics facilities, potentially increasing the risk of fire spread to adjacent racks and compartments. The experimental configuration and data presented in this study are expected to serve as reference data for future research on rack-fire behavior.