An experimental study of loaded full-scale cold-formed thin-walled steel structural panels under fire conditions

This paper presents the results of eight tests on loaded full-scale cold-formed thin-walled steel structural panels, two tests at ambient temperature and six exposed to the standard fire condition on one side. The test panels used two types of lipped channels, 100×54×15×1.2 mm or 100×54×15×2 mm, each channel having two service holes, one near the top and one near the bottom. Three different load levels, being 0.2, 0.4 and 0.7 times the load carrying capacity of the same panel tested at ambient temperature, were applied during the six fire tests. At ambient temperature, failure was local buckling around the top service hole. Under fire condition, the main failure mode was overall flexural-torsional buckling about the major axis, with the lateral deformations of the test panels being mainly caused by thermal bowing due to temperature gradients. The interior insulation in some tests was burnt through and this had noticeable influence on temperature developments in the test steel channels. In two fire tests using the thinner channels, the test panels failed before 30 min that is considered to be the minimum standard fire rating of this type of construction.