Elevated Temperature Effects on Local Buckling of Wide Flange Columns

Steel wide flange columns under compression, which are adequately designed for ambient conditions, can fail through local buckling when subjected to fire. This is due to strength and stiffness reductions in the mechanical properties of the steel at elevated temperatures. The AISC Specification does not currently have a design equation for local buckling under fire. This work aims to build on previous studies to determine the local buckling capacity of the column under uniaxial compression at elevated temperature. Numerical models of wide flange steel columns were developed using ABAQUS and validated from previous experimental testing by others. Axial load was applied at ambient and elevated temperature conditions and increased monostatically until failure. The model incorporated geometric imperfections and residual stress. Parametric studies were performed to study the influence of temperature (ambient, 400°C, and 600°C) and section slenderness on local buckling behavior. Results of this study will help to formulate design equations for wide flange columns under fire load to be incorporated in the simple method of analysis within Appendix 4 of the AISC Specification.

Learning Objectives:
Evaluate the behavior of wide flange steel columns at elevated temperatures under local buckling as compared to local buckling at ambient conditions and to recommend design equations to capture local buckling effects at evaluated temperatures.

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