New concrete filled double-tube (CFDT) sections consist of an inner and outer tube with fire protection mortar (FPM) filling the cavity between them and the inner tube also filled with concrete or not. An investigation into the fire performance of CFDT during the standard fire test is reported. Six full size FPM filled CFDT columns were designed for the fire tests. Detail failure modes of overall specimens and each component in the columns as well as temperature, deformation and fire endurance were presented. It showed that the fire resistance in the CFDT columns is significantly higher than that in concrete filled steel tubular (CFT) columns. Investigation into the fire performance of the columns reveals possible solutions to improve the fire resistance of CFT members.
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