Quantitative risk assessment methods of evacuation safety for collapse of large steel structure gymnasium caused by localized fire

• Assessment of casualties caused by the collapsed structure in fires is proposed.
• Available evacuation time can be determined by the modified temperature rise model.
• Flame thermal radiation effect on the steel members is considered in modified model.
• The required evacuation time can be determined by the proposed evacuation model.

A risk assessment method was proposed to evaluate the evacuation safety in the collapse of a large steel-structured gymnasium caused by localized fire. The criterion for safety evacuation was that the available evacuation time was greater than the required evacuation time, which could be determined by a proposed steel-temperature rise model and a proposed evacuation model, respectively. In the proposed steel-temperature rise model, not only the effects of smoke thermal radiation and convection, but also the effects of flame thermal radiation on steel components were considered. In the evacuation model, the required evacuation time was determined mainly by the following factors: distance from the farthest point to the safety exit, personnel evacuation speed, width of evacuation exit, and density of personnel. All these results and experimental data obtained in this study provide valuable references to fire simulation, hazard assessment, and fire protection design.