Study on the Vulnerability of Steel Frames Under Fire Smoke Propagation

The prevailing fire-resistant design of steel structures typically relies on the premise of localized heating, whereas the overall temperature increase resulting from the dispersion of hot smoke is frequently oversimplified. These theoretical simplifications may result in considerable structural safety risks. This research utilized the Transient Thermo-Mechanical Coupling Theory and developed a double-layer steel frame finite element model using ABAQUS 2023 software. The simulation of multi-physics field coupling involving smoke convection-radiation heat transfer and nonlinear structure response in fire situations was accomplished by establishing 24 sets of comparative conditions over three distinct premises. Upon comparing the conditions with the greatest displacement values across the three situations, it was concluded that when hot smoke is produced in the initial room, it commences diffusion into adjacent rooms both horizontally and vertically. In comparison to the scenario that disregards the dispersion of hot smoke, the displacement of the components escalated by 342.3%. The dispersion of hot smoke reveals that the displacement of components in the center room of the fire’s origin was 23.1% greater than in the corner room, while the displacement in the second-story room was 115.6% greater than in the first-story room. The use of fireproof coating markedly diminished component displacement in the context of hot smoke dispersion, achieving an 82.8% reduction in displacement among components in identical positions. The enhanced vulnerability model augmented the precision of forecasting the ongoing failure of steel frames by 29.1%.