Abstract: In order to study the response mechanism of actual rescue factors to building collapse during fire rescue, this paper adopted numerical simulation to simulate the high temperature of a three-story steel-concrete frame structure under fire, and obtains the temperature field and displacement changed under the conditions of automatic spray system, fire fighters water cooling, high frequency vibration of engineering rescue machinery and other factors. And the simulation results were found to align well with experimental data. The effects of various parameters on the structural collapse were discussed. The results revealed that longer exposure to fire led to greater displacement deformations in the fire-affected area. Significant displacements were observed in the non-fire-affected area due to the transfer of heat through combustible materials, and the maximum displacement deformation is 7.57 mm. Moreover, high-frequency vibrations caused significant instantaneous displacement fluctuations. The maximum displacement fluctuation is about 3 mm. Finally, it was found through simulation and experimental verification that short-term water cooling (within 10 min) had minimal impact on the displacement of buildings under fire, with displacements being only one ten-thousandth of the building's span. Therefore, it can be concluded that the high-temperature effects induced by fire loads have the greatest impact on the fire resistance performance of building structures once firefighters enter the fire rescue site, while the resonance frequency of large-scale engineering machinery significantly affects the instantaneous fluctuations of the structure, and short-term water cooling has minimal overall impact on the building.

Key words: rescue factors, buildings collapsed, reinforced concrete, fire resistance performance