Effect of Boundary Conditions on the Creep Buckling of Steel Columns in Fire

This paper presents highlights of a preliminary computational study conducted using Abaqus to investigate the influence of boundary conditions on the creep buckling behavior of steel columns at elevated temperatures due to fire. W12×120 wide flange columns with the unsupported length of 240 inches are used in the simulations. Thermal creep of steel is modeled following equations proposed by Fields and Fields for the creep of ASTM A36 steel. Four different classical support conditions and seven imperfection amplitudes are considered to quantify the effect of boundary conditions on the time-dependent strength of steel columns in fire. Thermal restraints, both axial and rotational, were ignored in the analyses. Representative results from creep buckling tests simulated at 500 °C are presented and discussed. Results from creep buckling simulations presented in this paper indicate that the rotational and translational restraint at the column ends along with the initial crookedness of the column have a significant impact on the predictions of the time-dependent strength of steel columns subjected to fire.

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