Performance of steel moment‐resisting beam‐supporting column transfer structures under fire

Abstract

SummaryThis paper investigates the structural fire response of steel beam‐supporting column transfer structures. Two three‐story (Case 1) and seven‐story (Case 2) structures with different span lengths are designed first to withstand gravity and seismic loads. All the structural members are also designed to meet their required fire resistance ratings based on the ISO834 fire. The structural vulnerability is then evaluated under two fire scenarios: the natural fire as a uniform and the traveling fire as a nonuniform temperature distribution inside the structures. The fire loads are applied to the first story of the structures where the structural irregularity is evident. The natural fires are determined based on Eurocode 1 and based on different opening ratios of 0.04, 0.067, 0.08, 0.12, and 0.16 to provide different duration of the heating phase. The results indicate that under the uniform fire scenarios, Case 1 collapses after 134 min under the opening ratio of 0.04. As well, Case 2 collapses under the opening ratios of 0.04, 0.67, and 0.08 at 95, 142, and 160 min, respectively. The results also show that under the nonuniform fire with a size of 25%; Case 1 collapses at 89 min, and Case 2 collapses at 93 min. Although it is believed that the cases studied should logically remain stable under possible fire scenario, the results indicate that this is not a true presumption. The results of this study provide beneficial information about structural fire response of beam‐supporting column transfer structures as an important structural irregularity.