Experiment of Heat-Moisture-Force Coupling Effect on Mechanical Behavior of Square Concrete-Filled Steel Tubular Stub Columns Under Axial Compression After High Temperature
Water vapor will be generated inside the concrete-filled steel tube(CFST)when fire occurs.In order to explore the heat-moisture-force coupling effect on mechanical behavior of CFST subjected to axial compressive load after high temperature,the tests of 10 square CFST columns under axial compression after high temperature were conducted.The effect of factors such as the number and arrangement position of air venting holes,axial compression ratio and heating time on the mechanical behavior of failure mode,axial compression stiffness and residual bearing capacity was analyzed.The results show that the failure mode is shown as crush failure mode.Under the same condition of other parameters,compared with that before heating,the axial compression stiffness decreased by 69.1%,73.3%,and 76.4%,respectively,and the residual bearing capacity decreased by 15.8%,16.2%,and 21.7%,respectively,with the increase of the number of venting holes from 2 to 4 and 6.The axial stiffness decreases with the increase of the axial compression ratio.With the extension of the heating time,the residual bearing capacity firstly increases and then decreases with the increase of axial compression ratio.The results of this paper can provide a reference for the fire resistance design of CFST columns and the damage assessment and strengthening of such structures after fire.
heat-moisture-force coupling effectsquare concrete-filled steel tube(CFST)after high temperatureaxial compressionmechanical behavior
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