ABSTRACT
This paper presents the results of 6 tests on full-scale cold-formed thin-walled steel panels under fire conditions. In each test, the panel, which measured 2.2mx2mx 125mm and was made of one layer of 12.5mm gypsum plasterboard on each side, 100mm deep cold-formed thin-walled lipped channel sections and lightweight interior insulation, was loaded on top and exposed to fire on one side. Two types of lipped channels were used, one being 100×54×15×1.2mm and the other being 100×54×15×2 mm. For each type of channels, three different load levels, being 0.2, 0.4 and 0.7 times the load carrying capacity of the same panel at ambient temperature, were applied. Fire exposure was according to BS 476. The main failure mode was overall flexural-torsional buckling about the major axis due to thermal bowing. The performance of gypsum plasterboard and interior insulation in fire was clearly one of the critical factors in affecting the panel behaviour. In some tests, the gypsum plasterboard fell off and the panel structure failed immediately afterwards. In other tests, fire burnt through the lightweight interior insulation and caused steel on the unexposed side to rise in temperature rapidly, leading to panel failure. These observations will have important implications on modelling of panel behaviour in fire.
