Fire tests of non-sway loaded and rotationally restrained steel column assemblies

Abstract Columns are critical members of a structure. Because of various interactions between a column and its adjacent members in a complete structure, the loads and boundary conditions of the column change under fire conditions. In order to carry out accurate assessment of the fire resistance of a column, it is necessary that the variable loads and boundary conditions of the column be precisely evaluated. To investigate structural interactions, it is important that such evaluations be performed when the column is part of a realistic frame structure. The Structures and Fire Research Group at the University of Manchester has recently performed two series of fire tests to examine some of these changes experimentally. In each of these fire tests, a non-sway loaded steel column, rotationally restrained by two loaded steel beams, was exposed to fire attack. The applied loads were kept unchanged throughout the fire test so that the fire test simulated a column with free thermal expansion. The objectives of these tests were to evaluate how bending moments in restrained columns would change and how these changes might affect the column failure temperatures. This paper describes the test set-up and how bending moments and axial loads in the restrained columns may be obtained from various measurements. An initial analysis of the test data has been carried out and this paper presents the results, to assess whether the test set-up performed satisfactorily. A future paper will discuss how these experimental results may impact on fire-resistant design of steel columns forming part of a complete frame.