A strategy for the fire testing of reduced scale structural models

A strategy for the fire testing of reduced scale structural models is developed which takes into consideration all significant thermostructural responses. An investigation of the thermal distributions within a structural element allows fire curve, thermal input and structural displacement output to be linked as cause and effect. Dimensional analysis permits the definition of the conditions necessary for dynamic similarity between model and prototype. An equivalent model fire curve is derived which can be mapped by a simple time scale factor on to a standard fire curve, though distortions due to film effects are noted. Errors due to temperature dependent properties are removed due to the nature of model and prototype temperature distributions. The principles are sensibly validated by low temperature experiments on perspex models of different scales. Finally, it is noted that a model test method would be advantageous for the provision of statistically meaningful amounts of indicative test data, with particular reference to parametric investigations. However, it is recognized that one-off full-scale tests must be conducted to provide the best final assessment of fire resistance.