Experimental study on temperature distribution of sandwich panel joints in fire

Previous research have demonstrated that significant cost savings can be achieved, if cladding panels forming the building envelope are used to provide stability. There is research information and design guidance available for normal temperature design. However, the information available for fire conditions is very limited and it is not known if the panels are able to stabilize steel frame members also at elevated temperatures. The stiffness and resistance of joints, cladding panels and connectors are required for the assessment of interaction between cladding and frame in fire. Temperatures of those components are in important role when evaluating the stabilization effect. This paper presents an experimental research conducted to determine the temperature fields in sandwich panels, supporting structural steel members and screw connectors. Eight full-scale fire tests were carried out where the structural steel sections supporting sandwich panels were exposed to ISO 834 fire attack on three sides. The test specimen consisted of a fire protected steel beam and load-bearing sandwich panels with both mineral wool and polyisocyanurate (PIR) core. Two different steel beam sections were used in the tests: HEA 160 (S355) and RHS 150x150x8 (S420). This paper introduces the experimental research and the main observations related to the temperatures. The results show that at failure of the specimens the measured screw temperatures were very different in HEA and RHS tests. The temperatures in HEA tests were much higher than in RHS tests the maximum difference in screw
point temperatures being over 400°C. In all the specimens, screw head temperatures were very low throughout the tests, well below 100°C. The tests were part of ongoing RFCS project STABFI.