Abstract: Steel frame connections are often composed of multiple connecting components, whose differential performance degradation under fire may lead to joint failure mode reconfiguration. Moreover, due to the thermal insulation effect of floor slabs, the heating and loading conditions of beam connections in the hogging and sagging moment regions can differ significantly after column failure, thereby influencing the progressive collapse failure modes of the structure. To clarify the failure evolution of steel frame joints under fire, this study uses the top-and-seat double web angle (TSDWA) connection as an example. Component temperature-bearing capacity functions were established under different failure modes. The failure of the component with the lowest critical temperature was adopted to characterize the substructure failure mode, based on which a theoretical prediction model was developed for fire-exposed steel frames with TSDWA connections. A substructure numerical model was also developed, and its results were compared with those of theoretical predictions. The predicted failure modes in the hogging and sagging moment regions under different design parameters were in a good agreement with the numerical results, and the relative error between the predicted and simulated critical failure temperatures is within 15%. These findings demonstrate that the model proposed exhibits a good reliability and can provide a useful reference for the rapid assessment of failure modes and fire resistance duration of similar steel frames under progressive collapse scenarios.