Behavior of Steel Columns under Fire Loading

This paper presents the behavior of A992 wide flange steel columns under fire loading. Experimental tests were conducted to investigate the structural-thermal response of steel columns subjected to axial loads and elevated temperatures. Two identical W14X53 specimens were tested under (i) non-standard fire loading to determine the axial load capacity at elevated temperature and (ii) standard fire loading to determine the buckling temperature of the axially loaded steel column. For the non-standard fire test (Test I), the monotonically increasing axial load was imposed on the steel column under steady-state heating condition. For the standard fire test (Test II), the steel column carrying the sustained axial load was tested under transient heating condition. The structural-thermal responses of steel columns observed in Test I and Test II were compared including column end rotations, lateral and axial displacements, and steel temperatures. The measured column buckling behaviors were also compared to those obtained by 3D finite element analyses. The results indicated that the end rotations and displacements of the steel column before buckling were affected by the sequence of applied loading. Both Test I and Test II provided the similar prediction of axial load capacity and buckling temperature of the steel columns.