Proceedings of the Annual Stability Conference Structural Stability Research Council San Antonio, Texas, March 21-24, 2017 Effect of Boundary Conditions on the Creep Buckling of Steel Columns in Fire Mohammed A. Morovat 1 , Michael D. Engelhardt 2 , Todd A. Helwig 3 Abstract 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. 1. Introduction The behavior of steel columns subjected to elevated temperatures due to fire is affected by many factors. One of the critical factors affecting the strength of steel columns in fire is the influence of material creep. Defined as time-dependent inelastic deformation, thermal creep of structural steel results in the creep buckling phenomenon, in which the buckling capacity of a steel column depends on the duration of applied load as well as the slenderness and temperature. In addition to the influence from material creep, buckling capacity of steel columns at elevated temperatures is significantly affected by their boundary conditions, mainly the end-support conditions and initial imperfections. The effect of boundary conditions on the buckling behavior of steel columns at room temperature is very well documented in the literature on the stability of steel columns (Ziemian 2010). However, literature on the impact of boundary conditions on the buckling capacity of steel columns exposed to fire temperatures is quite meager (Morovat 2014). Specifically, there is very little study on the effect of boundary conditions on the time-dependent 1 Research Scientist Associate, University of Texas at Austin, <morovatma@utexas.edu> 2 Professor, University of Texas at Austin, <mde@mail.utexas.edu> 3 Professor, University of Texas at Austin, <thelwig@mail.utexas.edu>