Abstract: In order to study the collapse mechanism of the stainless steel umbrella structure under actual fire scenarios, this paper establishes and validates a finite element analysis model based on the fire test of a stainless steel umbrella structure with a scaled-down size of 1：4. The thermal-structural coupling analysis method is then employed to research the fire-resistant performance of the structure under different fire scenarios. The results demonstrate that the relocation of the fire source has a considerable impact on the fire resistance performance of the umbrella structure. When the fire source is at the same horizontal height, the fire that occurs under the secondary strut with a small cross-sectional area will cause the entire structure to collapse and suffer damage, whereas when the fire source is located under the primary strut, it will only cause localised damage to the structure in the area under fire, with the remaining structure retaining a certain load-bearing capacity.

Key words: stainless steel, umbrella structure, temperature field simulation, thermal-structural coupling analysis, continuous collapse