This paper investigates the collapse mechanism of a long span space structure under fire. The mechanical and thermal properties of a space structure change drastically when subjected to a fire. The nature in which the space structure fails is dependent on a number of factors including fire load, shape and properties of the space structure and its materials. In order to fully analyze how a space structure would fail in these conditions, a multi‐physics thermal mechanical analysis model was built in ANSYS software. The chosen prototype space structure, Kings Cross Wester Concourse roof is modeled. The models were created using a series of complex features and were made to be geometrically sound with alignments between each member. Coupled steady state thermal and static structural analysis was performed and collapse mechanism of the space structure under fire were investigated the effectiveness of using finite element analysis software for large assemblies' analysis is also discussed.