Full-Scale Fire Resistance Testing and Two-Scale Simulations of Sandwich Panels with Connections

To understand sandwich panel behaviour under fire, expensive full-scale tests, or potentially more efficient fire-structure simulations can be carried out. However, these simulations have only been demonstrated to work for specific applications, either on the global scale (a fire on a simple panel) or on the small scale (a temperature load on a single screw connection), often loaded by a standard fire curve. In this paper, the quality of simulations for combined situations is investigated, i.e. a furnace fire on a set of panels including details and connections. First two existing tests are introduced, a sandwich panel facade test and a studs bolt test, followed by the presentation of their basic fire-structure simulations. In general, the heat transfer analyses agree well with the tests, whereas the structural response analyses need investigation: For the first test, out-of-plane deflections are overestimated at the beginning of the test. A parameter study indicates that this is most likely due to adhesive decomposition, resulting in face delamination and related instabilities. For the second test, the basic simulation does not show any failure, whereas the test failed by vertical bearing. However, with a two-scale model the ultimate load is estimated, and increasing vertical displacements and the onset of vertical bearing are predicted. It is concluded that future tests should include more simulation-relevant measurements. Also, global-scale models need to include features specific to the structure to be simulated, only known after tests and basic simulations, and connections may be decisive for global-scale behaviour, which can be incorporated by a two-scale model. Finally, the tests exhibited complex behaviour across different scales, and modifications and improvements of the simulations increased their fidelity. Therefore fire-structure simulations should always be verified with tests and compared with basic simulations, and modifications in the simulation models should be anticipated.