Effects of Fire on a Tall Steel Building Designed to Resist Progressive Collapse

Design for progressive collapse resistance requires that the structure remains stable in the event that a primary structural member is removed following an extreme event such as blast or impact. However, these methodologies do not take into account the potential hazard of fire that is often a byproduct of an extreme event. This paper examines the fire resistance of a prototype steel high-rise building, which meets progressive collapse requirements per GSA. The building is modeled with the removal of a perimeter column thus simulating a consequence immediately following an extreme event. The building is then subjected to uncoupled thermal - structural analyses representing various fire scenarios based on the following parameters: (1) fire protection, (2) fire type, (3) location, and (4) fire spreading. The results show that even though the building meets progressive collapse design requirements, if the building sustains localized damage to the extent where nearby fire protection is removed or damaged, a subsequent fire may quickly lead to building collapse. While this finding is for one particular building prototype, it is a potential concern particularly for high-rise buildings, which must remain stable for a substantial time to completely evacuate building occupants.