Steel Columns Subjected to Thermal Gradients from Fire Loading: Experimental Evaluation

Abstract

This paper presents the behavior of axially loaded steel columns subjected to thermal gradients through their cross sections. Experimental tests were conducted on full-scale wide-flange steel columns with W8×35 and W14×53 sections made from standard grade 50 steel. The experimental investigations confirmed that variations in fire protection thickness had significant influence on the thermal gradient developing through the steel cross section. Thermal gradient along the flanges caused bowing of column specimens toward the hotter side. Thermal bowing introduced second-order moments and adversely affected stability, leading to failure of column specimens by inelastic flexural column buckling. The experimental behavior and results were compared with those obtained from detailed nonlinear finite-element analyses of the tested specimens. These nonlinear finite-element models utilized standard (temperature-dependent) material properties, and reasonably predicted the axial load-temperature-deformation behavior and failure temperature of column specimens subjected to nonuniform heating.