Abstract
The authors had already examined the fire resistance of concrete-filled square steel tubular column, without fire protection, under constant axial load. These columns developed local buckling in the steel tube, but the fire resistance was maintained due to the transfer of the axial load from the steel tube to the concrete. In this paper, we have experimentally examined the mechanical behavior and fire resistance of these columns under axial load and bending moment. We had two types of heating tests. One type was carried out under eccentric axial load and another type was carried out under axial load and bending moment transfered from beam. The results obtained from the tests are summarized as follows: (1) Under an eccentric axial load, the end of the column members have sufficient rotation capacity. (2) Considering the framed structure at the occurence of fire, as the decrease of yield stress and rigidity of steel tube due to the temperature rise, the quantity of transfer of bending moment from beams to columns decreased. (3) Finally, the results were similar to those obtained in the heating test of the composite columns subjected to central compressive load, and consequently the fire resistance of these columns was mainly determined by axial load ratio.
